New Fangled Hoses & SEACOCKS! [Archive] - Pearson Ariel Association Forums

Scott Galloway

08-13-2004, 12:16 AM

You know, I am actually not doing this job myself.

I have no trailer and no lomng term parking space, and time is of the essence. I will finish the head portion for the job once I am back in the water, and that will mean messing with the white hose. Therefore, I posted the question that began this thread.

I originally began to do what I thought would be the modest job of replacing some hoses, but I ran into a problem with one-and-one-half inch fiberglass cockpit drain pipes, two one-and-one-eighth-inch rubber plug Grocco sea cocks, and one frozen head tapered bronze plug outflow seacock.

A previous owner had installed on and one eighth inch un-reinforced clear plastic line on the cockpit and sink lines, which he stretched to fit on a one an one quarter inch "T" and the one and one half glass cockpit drain pipe. After fooling with this for a few days, I decided to consult with the yard in which my boat is captive.

I am hauled out and paying for yard parking space. The longer I stay the higher the daily rate goes. I am rushing to get to back to the water, so that I can drop the mast and start accident repair to my mast and deck.

While I am hauled, I had hoped to change a few hoses, but I discovered (in the opinion of the yard) that I needed new through-hulls and valves. So this was the hose project that began with a surveyor's recommendation, then moved to a bewlidered owner, whjo sought a yard consultation, and finally contracted for replacement of through hulls and valves by said yard: And alll because of a sticky problem in which I could not locate suitable parts and I needed some advice.

Unfortunately, my littel hose project became an expensive complete plumbing rehabilitation project inclusive of through hulls. When I began this thread by posted my question on that white hose, it was because we were having some problems with the stuff. The silicon grease thing is certainly worth trying. MY Yard folks use the hot water trick. I still have to plumb the rest of my head system, but I wanted the through hulls and valves connected before I launched. Thanks to my yard folks, they are now connected, but I am amazed at how difficult the process of working with the white hose appeared to be.

I also had some original tapered plug seacocks with no backing blocks on the head, one of which was frozen. I endeavored to free the valve, but failed. I failed mostly in that I failed to recall that Dan Spurr's "Boat Book" (in which he described his Triton rehabilitation in detail) has a spiffy protocol for freeing stuck tapered plug seacocks that involves a wooden hammer.

Even when I brought my errant seacock home and put it into a vise, a wooden hammer did not work, but a solid swack with a steel hammer loosened the tapered plug and the valve is actually in good shape, even though after being frozen closed for what was probably at least ten years. The seacock was still full of seawater. Of course it was. Where would the water go? If I can ever get the severed shaft of the through-hull out of it, it would be reusable.

My surveyor originally recommended pulling the seacock, cleaning it up and seeing if it was still good, but the seacock wasn't backed by a backing plate, so I asked the yard to loan me an expert, and they did. My local yard recommended that I replace the valves and through hulls, and that's where this project became expensive.

The yard apparently uses two types of hose for non-engine related sailboat hoses.

1. That white stuff. The installation of this white stuff became problematic. But it is now installed for the cockpit drains and head.

2. The clear black spiral reinforced hose sold as "bilge pump" line by West Marine. This connects the sink to a "T" in the port cockpit drain line.

The next task will be for me to install the white lines to the holding tank and through deck pump out.

So what's wrong with the white stuff for the cockpit drains besides the difficulty of installation? The cockpit drains and sink are non- pressurized. The white stuff is reinforced santitation hose. Is their vulnerability in having this stuff on the cockpit drains or sink?

How about that black spiraled bilge pump hose on the sink?

By the way, I found it interesting that the head seacocks, which I assume were original equipment, were not mounted to backing plates, but they had enlarged bronze bases. They were bedded solely with silicon?

My cockpit drain sea cocks were more recent, I think. They were bedded in some hardened cream-colored goop, and also some silicon. I am not a silicon expert, but bedding through hulls below the water line doesn't seem like a terribly good place to use it.

On the other hand forty years with no leaks is a pretty good run!

Theis

08-14-2004, 08:12 PM

Use the white stiff drain hose. Soften it by soaking it in BOILING water. A few degrees lower than boiling, as I recall, makes a great deal of difference. When you pull it out of the water, you have to move fast, but the stuff is pliable, can take turns without collapsing, and is solid.

As for the cockpit drains, there is no room for error using hosing having less rigorous standards. From experience, I can tell you that you want no possibility that there will develop a pinhole leak as the plasstic ages - unless you are trying to collect insurance. Watch out for any hosing that has a metal coil inside it (like neoprene) to keep it from collapsing. That stuff, I fear, deteriorates because of a chemical reaction between the steel and the "rubber/plastic/whatever".

marymandara

08-14-2004, 08:34 PM

Hmm...
Good rubber 4-ply exhaust hose is a little stiff, but a heat gun eases it...silicone grease helps it..and it is extremely tough. Think about what it is used for! It's also, as far as I know, the standard and ABYC-recommended material for the job you are doing. Comes in lots of sizes...and, in fact, the original Pearson hoses were--guess what?

It is also worth considering in all this...that you don't want to go horsing on the fiberglass tubes harder than needed. Also, for the same reasons that it is important to have hose in there in the first place (production concerns aside)---the flexing of the sole, and the flexing of the hull (both are more than one would likely think)--you do not want an excessively stiff hose in there.

Does this yard do engine work/installations? Then...they should have the proper exhaust hose in inventory.

Not to seem contrary, but it sounds like a lot of wheel reinvention to me.

Dave

Scott Galloway

08-15-2004, 10:22 PM

So Dave,

With all that said, what do you think of this installation? (Port cockpit drain with sink connecting in "T")

The wood blocks were preexisting. The faint greenish color on the hull below the block is stain from corrosion from the old bronze seacocks. The wood blocks seem to be attached to the hull with some form of semi-hard tan stuff. I don't know what it is, but the yard drilled the blocks for one and a half inch thru-hulls an reused them, tan stuff and all. The old cockpit drain, through-hulls and seacocks were bedded with silicon and some of this tan stuff. (The head through hulls by-the-way were bedded solely with silicon.)

The white goop in the photo is 3M 4200. The through-hulls was bedded in 4200, and most of the hose connections also use it liberally. The vertical hose is that white santition hose we have been discussing on this thread, and the black striped hose connecting the sink is one and a half inch hose that West Marine sells as bilge pump hose. That is a West Marine nylon "T".

Note that the valve is mounted on the threads of the through-hull stem. It is not a traditional seacock.

After I saw the installation, I was surprised that they had not instaleld seacocks, sicne that si whatthey had removed. I discussed the installation with the yard manager, and he told me that this is their SOP, although they will install the flanged sea cocks if a client specifically requests them to do so. They feel that there is no difference in safety or durability of the through- hull, although they predict a shorter life for the valve than with traditional seacocks. They don't even seem to stock traditional seacocks in their chandlery.

With the exception of the flange and the fact that the sea cocks sold by West Marine have drain plugs, the valve mechanism itself appears to be very similar: Bronze with an electrically isolated stainless steel ball. So the main issue is flange with bolts or screws into the backing plate vs. tightening nut on the through-hull as a means of attachment to the hull.

On the one hand, it seems to me that a through- bolted sea cock adds three more holes to the hull but it is a very secure fitting, Screwing a traditional seacock into a wooden backing plate would prevent the seacock from rotating and there by loosening, but seems less secure than through bolting, and it would be impossible to tighten if the bedding fails below the block, without unscrewing the seacock screws.

Now these older primarily-mechanical systems were developed before 3m 4200 and similar adhesives were invented. With the advent of new adhesive bedding compounds, perhaps a tightening nut on a through hull and inline valves is a satisfactory or even a better approach, since one can tighten the nut if necessary.

However being the kind of guy who like traditional boats, I am the kind of guy who would sleep better with traditional seacocks. Any thoughts?

Absent an existing backing plate in good condition, the yard uses fiberglass backing plates. They did this on my head through hulls.

This installation conforms to nothing that I have seen in any book on the topic that I have read. but then again, I read mostly old books or those by traditionalists. My yard says they do this type of ball valve installation regularly and the installations work just fine, and last for many years.

This isssue alone would make a good topic for a thread. The cockpit drain system is now different than what I had before Before I had traditional sea cocks that were merely screwed into the backing plate with half-inch screws, and not through bolted.

My two head sea cocks were solid bronze tapered plug style valves with an integral flange on the base of each seacock, and no backing plates. They were bedded with nothing but silicon. Once the exterior mushrooms were cut away, they just lifted off the hull. This was probably an original installation folks. Spooky as that seems

Tony G

08-16-2004, 05:47 AM

Scott,
I could live with that. Somewhere in the crevices of my mind I keep hearing no, no, not silicon. I honestly can't remember where I read or heard not to use it on boat projects. Maybe it was just one person's opinion I've taken for gospel. I know 113 has silicon on her and my O'day has some on her too!
The other thing I noticed is you have some drain/scupper tails sticking down from you cockpit. When were those replace and what did you use. Yes, of course this is just a cheap ploy to get you to post some more pictures.
Thanks, Tony G

ebb

08-16-2004, 06:32 AM

My notes tell me this:

Don't use white corrugated hose for below water hookups. What you want is the most reliable stuff available. Only the best.
Use USCG, SAE J2006 R or R2
The best is silicone blue or, 2nd, EPDM black exhaust hose.
Auto hose has no standards.

Mass marine marketers carry Trident hose. But you probably will have to search for the silicone - which has a 10 year guarantee on it! For the few feet we need, it'll be worth every worry-free cent. Yeah, dollar.
I will use the same heavy smooth wall R hose for the blige pump pickups.
'Soft' refers to (2, 4, 6) multi layer polyester or fiberglass reinforcement - so that it doesn't collapse under pressure or bending. 'Hard' refers to spiral reinforcement of plastic or steel wire.
If you use steel wire reinforced hose on bronze fittings, you are asking for trouble.

You may find cuffs for corrugated hose ends that will allow an easier slip fit over hose connectors.
And for thick hose you may have to use s.s. T-bolt clamps.

marymandara

08-16-2004, 11:01 AM

The argument for ball valves, from an installer's perspective, is that they are lots cheaper, you could keep a bunch in inventory for a lot less than flanged seacocks...and they are easier to install.

The still-current argumant against is that all that weight and vibration load is sitting squarely on the threaded neck of the thru-hull. This is really bad if the thruhull meets a hot marina and there is an electrolysis issue, and can be bad if something comes adrift in the boat and goes slamming into the thing. It takes a whole lot to snap off or corrode thru a seacock, even if the thing is very pink and very old. The head discharge seacock in the Triton was both of the above and very stuck, to boot. No thru-bolts, either, just gooped to the glassed-in plywood backer. After I took out the thruhull barb, I still couldn't get it to budge. Had to finally smack it with a BIG hammer to get it free, but it didn't break.

Last summer I replaced all the thruhulls in a 1978 Pearson 30, as well as replacing all the fiberglass tubes with thruhulls. There were an number of simple thruhulls with ball valves in that boat, and using nothing but a pipe wrench I had no less than two of them break right off before the ball valve would turn to come off.

It wasn't THAT big a pipe wrench. I'm not THAT big a guy. I wasn't pulling any too hard, and I wasn't pulling at a goofy angle. There was no pinking that I could see. These things scare me.

Lots of boats have these installations like this, certainly more than have proper seacocks...because it is cheap and fast and there is no regulation that forces the maker/repair facility to do otherwise. I'm sure it works great 90 percent of the time, right? I just don't want to be aboard a boat that becomes the smaller number.

BTW...the one that broke off the fastest...the valve was turning, albeit with difficulty. All of these broke jaggedly (I think there were actually three that did) well below the valve and well above the hull. So...right next to this one...is where the owner kept his toolbox!

That all said, I'm sure what you have there will work...it wouldn't be my preference, but it will work...just treat it tenderly.

Best,
Dave

ebb

08-16-2004, 12:27 PM

Dave's right! The yard manager does not have your safety in mind, only his profit margin. It takes more experience to put in a seacock,

It takes more experience to install a flush thruhull than a mushroom.

To get the handle orientation correct on a ball valve, the guy tightens it a little more or a little less. On a seacock you have to trim the tail of the thru hull and you have to think where the small fastenings go in relation to where the handle will end up. You probably have to put it together dry a couple times. The backup pad has to be 90 degrees to the thru hull - you can cheat with a ball cock. On a cramped boat, the handle has one place it can go plus or minus one degree.

The ball cock on a thru hull tail piece is an accident waiting to happen. A proper whack of a "tool box" against it could break it off right there at the exposed threads, which have relatively little meat on them. With a smidgen of dezincing your new sanitation tubes won't mean a thing. Especially if the last time you changed your seacocks was in 1978.

It's a big if, but if you ran the ballcock down to the thru hull backing nut so it would be less likely to "tip" when hit, that you could argue ok. Seacocks with their wide bases were designed for secure installs. Suggested on another post that a first class seacock install would not necessaryly require the flange fasteners go thru the hull. just into the backing block.

Scott Galloway

08-18-2004, 11:36 PM

Thanks for all of the comments folks.
here are a few answers:

Tony,

Drain/scupper tails sticking down from your cockpit? Shucks, I thought those were original. They seem to be part of the original deck molding on hull 330. They take 1 and 1/2 inch hoses You wanted some more photos. Here is one of the cockpit drain opening before the new fitting. The wood block is evident above the mesuring tape, but the tape measures "glass thickness only" at a little less than one inch. As I recall it measured 7/8 inch.

Ebb,

That isn't white corrugated hose in the photo above. That is Sealand "OdorSafe" sanitation hose with a smooth interior. It is stiff as can be, and hard to fit over the barbed plastic and bronze fittings on my boat. One the other hand I have noted that the stuff seems tight on some plastic Y valves on the West Marine shelves and almost too loose on others, so go figure. It seems strong and yet somewhat flexible. It just doesn't stretch easily. However printed on the outside of the hose are warnings about not exposing it to petrochemicals, solvents etc. So one would have to be careful about spilling solvents in ones cockpit, bit then again wouldn't that apply to most hose?

To all:

I agree with you all about the seacocks. When one you raised the specter of a flying toolbox colliding with an exposed, threaded through-hull stem below the in-line ball valve, I came to better understand the difference.

Frankly when I decided to have the yard remove and replace the through hulls and seacocks, I took it for granted that they would be installing seacocks. The deed was done by the time I comprehended the nature of what had been installed. The next step was to attempt to undertand the difference. Your comments have been most helpful.

The yard tells me, and my surveyor tells me, that installing these in-line valves is SOP these days, but I agree with you all that seacocks would be a far better way to go. I suppose that if of these through hull stems were to break off in a ragged tear below the valve, about the only way to plug the hole would be to go over the side and ram a wooden plug up into the hole: A horrid little thought.

I better add a crew member to my list. We'll call the person who volunteers for that duty a plug monkey. I hope plug monkeys can swim.

Tony G

08-19-2004, 05:46 AM

Scott,
Geez, I must be spending too much time on this computin thing...eyes is goin'. In the picture added on the 16th it looks like there is a shiney brass tail hanging down from your cockpit. I had fooled myself into believing that was a different scupper than the original model. Your newer hull must have shinier fiber glass! Thanks for the pic just the same;) Tony G

ebb

08-19-2004, 07:29 AM

I think it is Tim (Lackey,) someone, who describes an accident in his cockpit where a can of acetone gets knockt over runs down the drain and
EATS
the cockpit hoses. The image I have is that the 'petrochemical' crystalized the plastic and a long crack developed in the white sanitation hose.

I, of course, never have mishaps, can't imagine a solvent more lethal than beer on the steerage deck, but.... 338 will have rubber hoses of some sort. But you can see a problem happening better on a white hose than a black one.:)

Scott Galloway

08-24-2004, 11:48 AM

The best explanation (with drawings) that I have found yet on the subject of seacocks vs. in line valves is in a posted file by Grocco on Valves and thru-hull installation. See the following page:

http://www.groco.net/Service-Manual/Sec5-Seacocks-SM/IBV-FBV-TB.htm

or if that doesn't work for you go to:

http://www.groco.net/images/seacocks/seacocks_FBV.html

and select "tech bulletin".

Groco states, "Groco does not recommend the use of in-line valves as seacocks for these reasons:"

So go to the tech bulletin for a printable two-page wonder on this subject. Among other things their reasons are:

1. No means of attachment of in-line valves can result of turning or loosening

2. If the fitting becomes damaged or broken there is no way to shut off the flow of water.

3. In line valves have NPT (standard tapered pipe) threads, which are not compatible with NPS (standard straight pipe) threaded thru hull fittings unless the thru-hull is machined with "Combination Thread". So installing an in-line valve onto a thru-hull fitting will create a mismatch of threads resulting in a minimal thread engagement between the valve and the fitting and an unsafe installation.

Groco then tells people who choose to install in line valves as seacocks. These instructions include:

1. Locating the valve out of the way of foot traffic,

2. Allowing no more than 1/2 inch between locking nut and the valve.

And to create a little controversy, I also discovered this page in my research:

http://www.captfklanier.com/articles/art5.htm

This page by Frank Lanier, a certified marine Electronics Technician and marine surveyor discusses seacocks among other things. It says in part,

“Considering the excitement and havoc a failed seacock can generate, the lack of attention they generally receive is almost criminal. According to the American Boat and Yacht Council (ABYC), a seacock may have either an integral flange that is attached directly to the boat’s hull, into which a through-hull is threaded, or a valve attached directly to the through-hull. Many boat builders believe the former is by far the sturdier installation, but in either case, ABYC standards require it to withstand a 500-pound load for at least 30 seconds.”

So this would imply that an inline vale is perfectly appropriate as a seacock. I looked up the American Boat and Yacht Council (ABYC), to se if they have posted their standards, only to discover that the relevant standard sells for $40. The complete set sells for over $200 to members only, with membership being $160 per year. Anyone know of a source of these standards in book form through any source?

ebb

08-25-2004, 08:20 AM

Scott,
looks like yer own research gives you the answer.
Maybe an 'expert' is someone who tells you what you 'expect' to hear?
For below the waterline valves there is what is best
and what is ok.

When I was going thru the process of buying 338, I found a marine surveyor who had the epithet 'Captain' printed in front of his name. His talent was to make a detailed list of obsolete equipment, including lifevests. I had to find out about the boat all by myself, didn't cost me a thing. :D

Bill

08-25-2004, 01:21 PM

For another discussion on seacocks, see the Sep/Oct '04 edition of Good Old Boat magazine -- pp. 42-43. Comes complete with illustrations.

One of the advantages of the ball-valve seacocks is that only occasional lubricating with a small amount of grease is needed. For tapered-plug seacocks, however, disassembly,inspection, cleaning and regreasing are recommended annually. :mad:

The article also warns about matching threads on through hull fittings and seacocks. Sometimes a straight thread seacock gets attached to a tapered thread through hull. The result is that the actual attachment is only about two threads of engagement. This may explain some of the "breaking" stories we've heard about the ball-valve seacocks.

ebb

08-25-2004, 05:42 PM

Yass, here we are on a HOSE labeled thread yakking bout seacocks and ball valves.

I'm glad we have agreed on the terminology, even tho most seacocks are made with balls and are, therefor, ball valves. I am, this moment, looking at a Gigantic 1 1/2" Maralon ball valve, the bottom of which measures 3 1/2" across. If this 6 sided HEX base met something close to that beam in the thruhull nut, you'ld have something that couldn't break off if you kicked it. There is no zertz fitting to grease the ball (which is the same material) - you'ld have to grease it when out of the water anyway. Suppose you made a doughnut washer filler as thick as the thruhull backing nut, laid it over the nut on the backing, and wound the ballcock all the way down to the fillermathingy. That'ld be pretty solid, might go with that.

You can't forget that your whole boat depends on that thruhull fitting, whether it is nylon with glass in it or bronze. If you is a ball valve kind of skipper.

As to which is better, it is a matter of what lifts your kilt. Because what we have here is a perfect example of prioritys. Old gristled salts might think it an advantage to pull preventative maintenance on a flanged seacock. Once a year sounds pretty good and you are certain everytrhing's OK. Like your winches. If you are bronze, you can take a little emory cloth and see if any parts are dull pink rather than yellow, check out how good your zincs are doing. With the ballcock you trust in luck, since you haven't looked at it anyway, and you pray a lot to the ball valve gods - hoping the bloody sanitation hose you got a good deal on doesn't go befor the handle refuses to turn on the maintenance-free ballvalve.

Hey, when it goes, unwinde it and put on a new one - if you don't turn the thruhull too, you'll be really lucky - maintenance with a flaire. B
Inline plumbing ball valves connected to an unsupported thru-hull came out of the production boat industry, Bayliners.

Man, it's G O O D to pull K P on the ole seacocks, up close and personal. :cool:

marymandara

08-25-2004, 05:55 PM

Some bronze seacocks come with good old fashioned waterpump-style greas cups on them, you just keep the cup filled with lubriplate and periodically give it a twist to force grease on in there. I like the Marelon variety better just because of all the issues of no corrosion-lightweight-superstrong-less money, but also, they are more-or-less self-lubricating.

Oh man, Ebb can have fun with that one!!! :D

Scott Galloway

08-25-2004, 09:44 PM

There are seacocks with tapered bronze plugs, and seacocks with rubber plugs and seacocks with ball valves integral to them. Seacocks have big husky bottoms with flanges and well-protected internal threads and they squat down against your hull or preferably against a backing plate leaving not a single thread of the thru-hull shaft exposed. Seacocks may be made of bronze or Marlon.

Usually, seacocks have three bolt attachments points on the flange. Usually seacocks have straight (NPS) threads on the bottom (seaward) side, which allows them to fit nicely, and deeply over the straight NPS threaded thru-hull shaft. On the top end they have tapered (NPT) threads, which permit the attachment of NPT threaded components of various types. A seacock is a seacock whether the integral valve within it is a bronze tapered plug, a rubber plug, a ball valve, or some other type of valve.

But there are also just plain old in-line ball valves such as one might install somewhere inboard of a seacock as part of your plumbing system. These aren't seacocks at all, but they are being installed in the place of seacocks regularly, and for some marine yards they have supplanted seacocks.

When you install one of these in lieu of a seacock, you leave an exposed section of the threaded shaft below the valve. groco doesn't recommmend that you use these in-line valves in tehplace of seacocks. Groco also warns that leaving more than one half inch of the threaded shaft exposed is not a good thing. (See previous post on this topic for a link to Groco information) These valves have tapered (NPT) threads on both the bottom (seaward) end and also on the top end. If you attached one of these in-line ball valves to a standard straight NPS thru hull fitting, the NPT threads will not provide a secure connection because of a mismatch of the threads with the NPS thru hull threads and the resulting minimal thread engagement.

Now that I have restated the obvious, allow me to also say that I learned today from the engineering department of large marine supplier that there is yet one more possibility. This supplier provides thru hull fittings with what they call "bastard threads". These "bastard threads" are somewhat similar to an NPS “M” mechanical thread used for assembly of construction scaffolding, but are somewhat different even than an NPS “M” mechanical thread. The “bastard thread” is designed to allow a minimum of three and one half turns until it is hand tight in a female NPT threaded fitting such as an in-line ball valve. They also commented that the industry standard specifies that the threads of the two components must turn three and one half turns by hand and be capable of being further tightened by a mechanical device thereafter.

The marine supplier attests that their thru-hull to in-line ball valve connection meets the industry standard, and that these installations are done regularly at marine yards in lieu of installing seacocks. They sell the same thru-hull with its bastard threads for use in a seacock that they also supply with NPS threads.

So just because your thru-hull has straight NPS fittings doesn't necessarily mean that the threads are standard NPS threads. When you are matching seacocks to thru-hull fittings, the NPS thread design on the two components may be somewhat different. This does not mean that the two threads won't go together, but you have to wonder a bit about whether or not you would want two different NPS thread designs in a bronze-to-bronze connection below water level, and particularly in a thru-hull. The marine supplier sees no problem with this as long as you really seal the connection.

As to whether all of this makes a darn bit of difference, my marine yard reports that they have been installing in-line ball valves in lieu of seacocks for over twenty years without a single reported failure, and that they rarely install seacocks anymore at all. My yard uses the above referenced supplier. The licensed marine surveyor that I used to assess my recent accident damage agrees with my yard that in-line ball valves are just fine, and says that they now represent the standard installation.

However, I still get a very warm and snuggly feeling when I crouch down behind a chandlery plumbing shelf and slip a 1 and 1.2 inch straight standard NPS thru-hull fitting all the way into a bronze Groco seacock, and I don't care how heavy that sea cock is. It feels good and just watching the threads spin down together puts the mind at ease. Nightmares about flying toolboxes subside instantly.

With simple shackles costing forty bucks, and the basic no-chart GPS running $200, why would anyone voluntarily select an in-line ball valve over a seacock to save forty bucks. A two-inch hole in the bottom of a boat is a formidable thing to face at sea.

And Bill, I had a long-sealed, tapered bronze plug, green-with-age seacock that was mounted directly to the hull with no backing plate and no bolts or screws to hold it in place. I assuem that it was original equipment. I wanted to rehabilitate the head upon haul-out. Bad idea. T'would have been a far far better thing to do and a far far cheapert thing as well to buy a porta-potti.

That seacock was so badly stuck that I could not free it. I finally did free it, but that was after the yard had cut it off the through hull from outside the hull, and after I stuck it in a vise on my work bench and tried all of the tricks in the book, including taking off all of the correct parts and using the wooden hammer on the backside trick. What finally did free the valve was a solid swack on the backside with a framing hammer. This is not recommended by any responsible party, but it did work. My guess is that the thing had probably been struck for more than a few years. Anyway, that started me down the long painful road to SEACOCK REALIZATION and the discovery all of the above factoids. As painful as it has been, I suppose that this is all in the way of education

Bill

08-26-2004, 02:38 PM

The next couple of photos reveal an interesting situation. The first photo shows the ball-seacock installed on Maika'i for the cockpit drains. Note, however, that whomever did the installation failed to use fasteners in the base of the seacock. :confused:

Bill

08-26-2004, 02:42 PM

Now, let's look at the non-seacock for the sink drain. The boat yard installed this one for me. A seacock like the ones on the cockpit drains was given to the yard, but they elected to install a ball valve instead. :confused:

It would appear that Scott and I are both victums of the yacht yard bandits :mad:

Bill

08-26-2004, 02:45 PM

Although the seacock installations on Maika'i are not the most desireable, I believe that they are safe since they are all out of the way of any loose tool boxes or tripping skippers . . . :cool:

Scott Galloway

08-26-2004, 10:55 PM

Hey Bill,

You have that same spiffy sanitation hose on your cockpit drains as well. That’s the stuff that started this thread. Sooth on the inside and odor free, but hard to bend.

I actually think that marine yards are responding to the market when they install in-line valves. I may personally not agree with the direction that the market is going. The manufactures of production boats don't always install sea cocks either. In fact, some of the prominent manufacturer’s just glass fittings directly to the hull with no thru-hull fitting whatsoever. My first boat had one of those for its cockpit drain. I showed this to the yard where I launched it way back back in 1984, and they cut it off and installed a thru-hull and ball valve for me, and I sailed that boat for about ten years without any problems with the valve....

Actually, my yard installs in-line valves and thru-hulls from the same supplier at a significantly lower price than sea cocks, but they will install higher-priced sea cocks if an owner specifically requests them to do so. And of course that means a higher labor cost too, since it is probable that the thru hulls will have to be cut to the correct length to permit the sea cock to be cinched down on its backing block.

The good news about my yard buying their parts from the same supplier is that the supplier's engineering department has thought out the thread compatibility issue (or at least they talk a good line) and they tell me (because I called them) that the valve set (thru-hull and ball valve) meets the ABYC standards. This is achieved with an NPT (tapered) thread on the ball valve spinning three and a half times by hand on the bastard NPS (straight) thread of the thru-hull shaft before it is hand tight.

So at least we have a supplier paid engineer's evaluation of the applicability of the parts to a below water line installation on the installations on my boat. That gives me a greater sense of confidence and confirms my yard’s decision to use ball valves and thru-hulls from the same manufacturer.

But if someone used shall we say, an Apollo ball valve on any old standard NPS (straight) threaded thru-hull made by someone else, that someone would need to know how many threads are engaged if that they wanted to comply with the “industry standard”. Groco flatly recommends against using ball valves in the place of sea cocks. Certainly, if you slide a thru-hull all of the way into one of their sea cocks, you will see a whole mess of threads engaged and none left exposed. I think that Groco’s recommendation against using in-line ball valves instead of sea cocks is prudent, but the industry may be going a different way, and by the way, this different way saves the customer money in both parts and labor cost at the time of an installation.

So in addition to the issue of someone or something knocking the valve off the stem or the exposed stem breaking we have the issue of whether there is sufficient thread engagement for normal vibration and wear and tear.

My yard says that they have been installing ball valves in their way for twenty years and many competent skippers are sailing all over the place with them without a reported failure.

But I have learned a valuable lesson in all of this, which is to clearly delineate what you want, and have a meaningful dialog with the Yard Manager before you make a final decision on any product decision. Then make that decision clear before you ask for assistance in a yard at haul out. The yard would greatly prefer that we make our preferences clear on the front end. The problem is that sometimes we just don't comprehend the issues at hand at the time the work begins.

When I hauled my boat recently (for the ffirst time ever), I never envisioned that I would need to replace thru-hulls or seacocks. I only intended to replace some hose, free up a stuck valve and evaluate the condition of and grease four seacocks, (two ancient tapered bonze plug seacocks and two somewhat newer but undersized rubber plug cockpit drain seacocks). Frankly, I was more concerend about an accident survey report, the condition of my rudder, and bottom prep and paint. These were my three major objectives for this haul-out. Indeed, had it not been for the accicent, I would not have hauled out until fall.

Once in the yard, I ran into trouble with my hose replacement project and one pesky stuck tapered bronze plug seacock valve that I could not free. When I asked for help from the yard, things started happening pretty fast, and I had not done any research on my options. My options seems to be jury-rig vs, replacemet on the cockpit drains and...well there did not seem to be any option on the head fittings at that time. I was pleased to have an expert from my yard with serious tools and years of know-how deal with the thru-hull issues while I rehabilitated my rudder, an area that I have researched through this forum and the Ariel manual.

I was talking today briefly to a very experienced skipper who uses Marelon in-line ball valves on thru-hull fittings and does trips to Hawaii in boats with them. He says that he will use Marelon sea cocks next time. They are lighter and there is no issue with corrosion. So this seems to be an evolving issue with many of us as new material and marine sealants come on the market. I think that it is a matter or preference, but my preference for a Pearson Ariel would be bronze sea cocks if I were to do it again.

Maybe next time I haul I will. When you look at the long term an investment o in a Groco full flow bronze sea cock with a bronze handle and stainless steel ball, it will probably last the life of the boat, whereas these in-line valves will have a more limited lifetime unless of course…

An editorial comment from Aug 27, 2004: And by the way, I hauled out today for the third time this month as a result of yet another leak in one of the valve/thru-hull connections. Two Groco full flow flanged seacocks and thru hulls are awaiting installation on my cockpit drain lines. See some photos of what and why on the "Cave Paintings" thread on the Gallary forum of this site.

And by the way, the white hoses are going away too, and that is where this thread began.

Bill

08-28-2004, 03:17 PM

Sure glad we're having this conversation ;) I could not figure out why the hose bib tail on the ball valve for the sink would not take more than a turn or so by hand before it stopped -- almost put a wrench on it :eek: Took it home and tried it on the "real" seacock . . . and it screwed in by hand just fine . . . !

From this bit of empirical testing, I conclude that one of the valves has straight threads and one of them has tapered threads. After reading Scott's magnum opus on the subject, I'm seriously considering having the ball valve removed and replaced with the seacock already in my boat stuff inventory -- when next we haul out for a bottom job. :cool:

ebb

08-28-2004, 07:34 PM

Safe to guess that seaacock sits on a tall 'backing plate' (Mound) so that the thruhull can be fully screwed into the seacock as the last step in installation. Kind of backwards from what you'ld expect. The seacock is mounted dry with the thruhull, the seacock is 'wet' mounted first, yours was probably glued in with 5200, hopefully polysulfide, left to set. Then the thruhull was screwed in as the last thing, hopefully with polysulfide. personally I would screw it in with lanoline or Dolphinite.

Thru hulls have a backing nut, which gets discarded when a seacock is installed on it. It couldn't have a nut if it had a tapered thread.

With enough rubber caulking the thruhull could fall out befor the hull would leak there, because the seacock completely covers it. And usually is screwed or bolted to the backing. The seacock has to have a female taper thread on top because that's where the plumbing begins.

Inline ball valves are exactly that, aren't they? They have no base. In line ball valves have tapered threads BOTH sides. Therefore you can't screw them down very far befor they start tightening up.

IMCO no one making inline ball valves makes a thru hull for them. Because they never were suppose to be used for under water inlets. Not only do they sit on top of the thru hull but they are not screwed very far on. And as I think Scott's photo of threads shows. you can see galling there where the mismatch has bent the threads. Tapered male to tapered female (if they are the same size) fit like socket.

I notice that Triton Tim uses inline ball cocks for above the static waterline plumbing exits. Also he has used premoulded auto hose for his cockpit drains, last I read. The reason is the tortured impossibility of bending short straight hose to compound curves. He writes a forthright description of his adventures under the cockpit - and in the lazarette.

Ron Basey in a How-To mentions nothing on the NPT, NPS anomally that Scott extracted from the marine plumbing morass. Thanks Scott. ;)

As to Good Old Boat's two pager on "Inspecting and maintaining seacocks 101" - the drawings are great. It's ok for guys puffing on their kaywoodies with the cuffs of their white shirts turned up looking for their tapered plugs.
But as we know, there's a lot more to the understanding of saltwater seacock. I hope, without much faith, that seacocks 102 comes along that will show how to install the things, how to pull maintenance, what to look for in a questionable installation. 103 might go further into seacock design, how to recognize if your chrome balls are flaking or your stainless stell one has crevis cracking, etccc.

ebb

08-29-2004, 07:35 AM

First this:

"And then again, when you sit at the helm of your little ship on a clear night and gaze at the countless stars overhead, and realize that you are quite alone on the great wide sea, it is apt to occur to you that in the general scheme of things you are merely an insignificant speck on the surface of the ocean, and are not nearly so important or as self-sufficient as you thought you were. Which is an exceedingly wholesome thought, and one that may effect a permanent change in your deportment that will be greatly appreciated by your friends." James S. Pitkin

This was inserted into the discussion on the above subject by some wag on

http://www.boating-forum.com/cruising/Sea_Cocks_169243.html
http://www.boating-forum.com/cruising/Throughhull_question_168351.html

(hope that's right!)
Their discussion mirrors ours, and is well worth a visit by anyone of us. Very good exchanges on serious business. :D

(ok, it doesn't come up,

I refound it by using google this way:
type in: seacocks www.boating forum
find Through-hull and Seacocks (about three down)
hit and light up "More results from www.boating-forum.com
Hitting these light ups here won't work. Have to do it thru google!!!

Hope it works. Edjikational. Worth the visit. Guys just like us. Only shorter winded. :o

Scott Galloway

08-29-2004, 12:16 PM

Hmmmm,

Ebb,

Those links didn't link for me.

Bill,

Your hose bib tail fitting issue is most curious. I don't know very much about pipe threads, but I know more than I did a couple of weeks ago.

From the information that I have gathered, I am under the impression that straight threads have their best application whenever mechanical strength is important.

As an example, straight NPS "M" threads are used in scaffolding that is quickly assembled and disassembled at construction sites. A watertight joint is not even an issue I construction scaffolding, but the joint being able to withstand significant lateral force is a big issue, as you might imagine. The joint gains its strength by the many many turns of the straight threaded male end inside the straight threaded female end.

Another application for (NPS) straight threads is on thru-hull fittings and the matching straight threads on bottom end of sea cocks. This is very important, I suppose, because if a strong lateral or other force were to break a pipe below a sea cock valve, the result would be catastrophic, and even more so if the break is ragged. So, straight threads on a thru-hull fitting mean that female threads inside of the bottom opening of the sea cock will spin round and round again down on the male thru-hull shaft until the sea cock is tightened down like a great big lock nut against the top of the backing plate, and the thru-hull flange is pulled up very tight against the hull. To accomplish this, the shaft on the thru-hull may have to be shortened somewhat of course by cutting it off.

This whole unit would probably leak of not bedded properly, because these are straight threads, but you have bedded the thru-hull flange, the joint between the inside of the hull and the bottom of the backing plate, and the space between the top of the backing plate and the bottom of the sea cock with a marine sealant. The compression created by tightening the sea cock down on the backing plate holds the unit together and maintains compression in what is a very complex joint consisting of sea cock, backing plate, thru-hull threads, external thru-hull flange, and marine sealant.

Now, if instead of a sea cock you use the in-line ball valve option like the one on your sink drain pictured above, the female lock nut can spin all the way down the male thru-hull shaft to the backing plate and tighten nicely against it, which means that the thru-hull flange will simultaneously be pulled up tight against the outside of the hull.

So when comparing a sea cock in the first case to a lock nut in the second case, the two are basically the same functionally in that the lock nut has straight threads and is essentially operating mechanically in the same way that a sea cock operates, but of course a lock not has no valve in it, and here is where the problem arises:

You have to deal with the open end of that thru-hull shaft. You want a shut-off valve, but you decide to be modern and forsake the traditional sea cock with its NPS threads bottom and ample mounting flange. So you select an in-line ball valve instead. Now my understanding of these in-line ball valves is that they have tapered (NPT) fittings on both ends, so you might find that your tapered NPT threaded ball vale will be incompatible with the straight NPS threads on the thru-hull shaft, or you might have a case where you do get the requisite number of turns recommended by the ABYC because your supplier thought about this somewhat, and used a non-standard (bastard) straight thread on his thru-hull to allow the female NPT tapered ball valve threads to slide down further in those bastard threads.

I was told by a supplier that the ABYC wants 3.5 turns by hand before the joint is mechanically tightened, but I haven’t read that anywhere. I did read in another place that the joint must be able to withstand 500 lbs of force over 30 continuous seconds without breaking. We have also read on this thread that Commander Pete was successful in breaking a couple of thru-hulls with these in-line ball valve installations by simply trying to remove them, and that they both broke in raggedly and not in a nice straight break below the valves.

I have been told by my yard and my surveyor that these installations are acceptable and done by most yards.

It is as of yet unclear why my brand-new system failed the second time in a week. We will know more when we get the parts out next week.

Now finally, once you are inside the hull and beyond the valve, all fittings that you are likely to encounter, including the top fitting on a traditional sea cock, wil have tapered (NPT) threads, because you not longer have a dual compression feature like that offered by a sea cock or lock nut and thru hull flange pulling a joint together with lots of goop in between.

So, once we are at the top end of the sea cock, or at either end of an in-line ball valve, we have entered the world of conventional plumbing with tapered threads offering their version for compression (which is created by the tapered threads coming together), and this makes for “generally” leak proof joints.

So having said all of that about a topic that I know very little about, I find it interesting that either your hose bib tail or in-line valve has straight threads while the other has tapered threads. The threads on the top of the sea cock, the threads on the top of the ball valve and the treads on the bottom of the hose bib tail should all be tapered threads, I would think.

Of course there are some people who will attach hose bib fitting with a female end directly to a thru hull shaft with no valve in between, and this is commonly done for above water through hulls as you know, so perhaps they make hose bib tail with straight threads as well as with tapered threads, but my understanding is that the top opening of both a sea cock and both ends of an in-line style ball valve would have be tapered NPT threads.

I am interested in how your sink drain ball valve to hose bib connection issue is resolved. Keep in mind that this sonnection is above the valve. The connection between the ball valve and the thru-hull is ven more of a concern.
:confused:

ebb

08-29-2004, 06:20 PM

Scott.
read the end of post #29 - follow instructions to the letter.

As post #28 intimates: THERE ARE NO THRUHULLS FOR INLINE BALL VALVES.
[ further research refutes this, at least for Marelon]

So you have to use the backing nut of the thru hull with suitable rubber compoubd to weld the fitting in place. Then you have to turn the NPT valve on to the NPS, which very soon stops turning. If the idiot keeps turning he or she screws up the threads on the thruhull fitting. And the glued in thruhull will start turning, And can possibly crack the threaded tube because it is thin and compromised by the very threads that make it a fitting. Remember, it is a fitting designed for a seacock. It is not designed to take a load.

Pipes and fittings come is thicknesses too. Schedule 20, 40, 80, 160 - same outside diameter but bigger number thicker wall. You might look for thicker wall thruhulls, if you will persist on screwing an inline valve on to your Schedule 20 thru hull fitting

It is possible that some manufacturer by now has a thru hull with NPT on top and a locking nut on NPS threads on the bottom. I don't know. It would be a no brainer to produce. NOW, if such an item does not exist, we have to assume some regulatory agency says they can't. If they can't then boat builders are installing inline valves illegally as seacocks, so is your yard manager, and your surveyor should go back to house painting. He's dead wrong too.

In a properly installed seacock, as specified above earlier post no b.s., The thru hull fitting can be said to FLOAT inside the seacock. There are NO loads on the fitting. There is NO backing nut on the thruhull when the seacock is there. You cannot compare the two installations, they are apples and oranges.

The seacock is installed first with the flange either lagged onto the backing block or thru bolted thru the hull.* The thruhull is then screwed into the unit and seated onto the hull if mushroom - or into the hull if flush. One merely screws the fitting in dry and out again for shortening until it fits perfectly. This is how it has been done for decades. NO strength is imparted to the seacock installation by the thruhull.

*If that mound under Bill's seacock is epoxy-chopped strand-cabosil mix and permanently affixed ie molded to the hull and if the seacock is glued on there with polysulfide or 5200, then IMCO it is good enough to screw some lags into the backing thru the designated holes - bolts being unnecessary.

Thank you.

Scott Galloway

08-29-2004, 11:56 PM

I am not sure that I would use 3M 5200 to bed a seacock, You would have one heck of a time removing it later. Also, 5200 is a slow cure so unless you will be out of the water for an extend time, I am told that 5200 is not a good choice for below water applications. If you feel differently, I'd be interested in knowing your perspective. Perhaps 3M 4200 (fast cure) might be a better choice if you don't want to use polysuylfide.

Sorry if my last post gave the impression that I was trying to explain how to install a seacock. I was not. Indeed, I have never installed one. What I was endeavoring to do was to give one view of the dynamics of what might be happening inside a seacock to thru-hull joint as compared to what might be happening inside an in-line ball valve to thru-hull joint.

Here are a few photos that might help. The first two are from Groco's webpage and show the thread locations and types of threads for both seacocks and in-line valves, and also the mounting configurations.

Scott Galloway

08-30-2004, 12:19 AM

Groco states,

"Groco does not recommend the use of in-line valves as seacocks for these reasons:

1. In line valves have no means of attachment tot he vessel hull or backing block...

2. if the connected thru-hull fitting become damaged or broken.... there would be no way to shut off the flow of water into the vessel.

3. In-line valves have NPT threads, which are not compatible with the NPS threaded thru-hull fittinmg (unless the thru-hull fitting is machined with 'Combination Thread'. Installing an in-line valve onto a thru-hull fitting will create a mismatch of threads resulting in minimal thread engagement between valve and fitting, and an unsafe installation. property damage and personal injury could occur. If you choose to install an in-line valve as seacock the thru-hull fitting ue dmust have 'Combination Thread.' "

Here is their in-line valve-as-seacock drawing: oops and
:eek: that didn't up-load, so I will continue with this series of photos at a later time.

Scott Galloway

08-30-2004, 01:29 AM

Here is that drawing of the in-line valve installation:

Scott Galloway

08-30-2004, 01:37 AM

I took my new Groco valve down to West Marine today and let it play with some Conbroco throughhulls, and hose barbs. I also had some fun with a Conbroco (Apollo) in-line valve. The labeled pictures tell the story. Please do not interpret the photos below as reflecting on the quality of any of the fittings. Instead these photos relate only on the use of in-line fittings vs. flanged seacocks for below-water, thru-hull applications.

First the seacock:

Scott Galloway

08-30-2004, 01:40 AM

Next the hose barb on sea cock:

Scott Galloway

08-30-2004, 01:41 AM

Finally, here is the in-line ball valve as seacock:

ebb

08-30-2004, 06:27 AM

Scott, Really impressive bunch of thumbnails you have here. Good Ole Boat and Con Racey would have done well to run their 101s through you. Now we should condense this info a bit so that it's available for everyone. :D

You have proven that
a seacock is a BOAT fitting.
An in line valve is a pluimbing fitting.

Tell us more about "combination" threads. Who, what, where, how.

5200. Be sure NEVER to use this legendary adhesive as a caulk, especially for thruhulls and seacocks. Never use any kind of polyurethane tube-paste for something that eventually will come apart. IMCO thruhulls have to be changed every once in awhile. Stripped threads, corrosion, dezincing.

Boat Life polysulfide is my choice for the thruhull. But I really lean toward Dolphinite. Depending on how elegant the pad and holes turn out for the seacock, might even consider Dolphinite for the flange to pad. Those Grocos have dissimular metals in them and will have to be replaced or bebuilt sometime.

Dolphinite IS a bit beyond the pale (beyond the yard manager anyway.) Would be interesting to have opinions on this. On a very neat seacock install (precise holes, close tolerances, flat surfaces, 90 degree holes) I would prefer to use bedding compound. If all bedding compound is used, would definitely thru-bolt the flange. Now we're talking about something that can be disassembled easy! Guys complain about having to sawsall the thruhull off (mushroom) when it is rubbered in place. A flush t.h. would be a real chore!

Anybody? A lot cleaner stuff to use! Cheaper too. Smells good.

Scott Galloway

08-30-2004, 12:34 PM

Ebb,

Sorry about the length of this thread, but the process of discovery was just that. As homework for my latest fast-course on this topic, I spoke today with the Groco factory. They now make all of their thru-hull fittings with "Combination Thread". By the way the ball valves on the one and one half inch seacocks are made of 316 stainless.

Groco recommends against installation of their in-line valves as sea cocks for below water application. Their one and one half inch sea cocks, which I have purchased, are recommended for below water applications. Their sea cocks have NPS threads on the bottom (seaward) end and NPT threads on top end.

They currently manufacture their thru-hull fittings with NPS threads with the exception of the top section of the threads, which are NPT threads to accommodate in-line valves for above water applications. This “Combination Thread” works well in the NPS threaded sea cocks manufactured by Groco.
These fittings have an "almost indistinguishable" transition from NPS to NPT threads near he top of their threaded fitting.

If you use this thru-hull in an above water application with an in-line valve, you need to be careful not to shorten the shaft, because if you did, you would be cutting off the NPT thread. In an NPS seacock fitting, the NPT threads at the top of the thru-hull slide right into the Seacock NPS threads without harming them since they are less wide than the NPS threads. Then, when more of the thru-hull shaft is inserted the NPS threads take over. If you have to cut the length of the shaft to accomodate your sea cock installation, it's no big deal to cut off the NPT thread section at the top of the thru-hull shaft.

Groco said that their products should not be bedded with 3M 5200, cause you can't get them off later but either ploysulfide or 3M 4200 are acceptable. I called 3M company a few days ago, and 3M told me that 4200 acts as a bedding compound only on bronze-to-bronze joints since on bronze, 4200 does not function as an adhesive. However 4200 does act as an adhesive on fiberglass, and that may cause you significant problems in removal, so there you go.

When setting the correct length for your thru-hull shaft for insertion into a below-water seacock, Groco's instructions say in part:

"
a. Step 1: …Measure the thickness of the hull and backing block together (Dimension A in the sea cock drawing above)

b. Step 2. Measure the total thread depth of the female NPS threads in the bottom of the seacock (Dimension B in the sea cock drawing above) Add A and B together.

c. If the thru-hull neck length exceeds this dimension cut the thru-hull length ¼ inch shorter than A +B. If the thru-hull length is shorter than A+B by more than ¼ inch, use a thinner backing block or use an Extra-long thru-hull fitting (Groco THXL Series)"

ebb

08-30-2004, 05:19 PM

How bout that, Groco got all their bases covered.
Could be their combo thread thru hull is a little thicker walled to leave some meat for the pipe threads up top. It ought to be thicker if they are inviting poeple to use their t.h. with unsupported inline valves.

When you think of reaching in at an awkward angle to shut off a hole in the hull, wouldn't you feel a lot better bearing down on the handle of a bolted-in seacock? On a sailboat, where is the waterline anyway?

Thanks to Groco for their forthrightness. However, Marelon zeros out the marina corrosion issue. One maker makes both pieces. I haven't researched if Forespar make a combo thread thrruhull. Why gamble, install seacock.

Old timers have a problem with 'Plastic.' The nylon Marelons are almost indestructable. They will melt in a fire, but so will the A/C. One problem is that they should be exercised more often than an alloy because nylon swells a little in water. You sometimes read that Marelon is for above waterline use. Forespar makes no distinction. 338 will have a few Marelon seacocks.

Notice on that forum site above, one of the guys did a very clever thing, used monel bolts for the flange. Maybe if Groco supplied the bolts, you might be sure the alloys matched. But with monel the seacock will corrode before the bolts, therefor the hole is covered, so to speak. Groco seacocks have ss balls or chrome on brass balls. OhOh, galvanic action! You carry spares. Even if you don't do the maintenance yourself.

As I say elsewhere, there are so many bronzes and alloy formulas you really can't be sure you have your little ship covered in terms of same alloys surrounding the holes in your hull. Did not notice if Groco told us what bronze alloy their seacocks are made from. If they are using mid-century formulas like Bristol Bronze for their in salt water/marina seacocks (like manganese b.) we may be in for trouble. We have an idea how long they lasted in the past but that probably doesn't jibe with the shore powered marinas we're tied up to today.

Hooray for Groco, anyway. Anything from Spartan???

Bill

08-30-2004, 05:30 PM

Just to make you feel good about Marelon, I've heard that the handles break. :eek:

Scott Galloway

08-30-2004, 11:37 PM

Groco's sea cocks have 316 stainless steel balls. Less expensive sea cocks and valves by other manufacturers have plated balls in their sea cocks. The Groco factory rep explained it to me this way:

If you have your boat in the water in a marine environment, then you want the top of the line. If you keep your boat on a trailer and launch it in fresh water occasionally, you might want to seek a less expensive solution. I understood that Groco might be considering other products for this market.

Groco advises strongly against the use of in-line ball valves for below the water applications. Recently I was reading somewhere about static waterline (a parked boat) vs. (I think they called it) a "dynamic waterline" when it comes to making discernments about the choice of sea cocks etc. I suppose that if asked I would define an "above water thru-hull" on a sailboat as any place that you can tack or jibe to be able to stuff a plug into from outside the hull without having to get into the water. Then again, I have had days where I saw daylight coming up through my cockpit drain thru-hulls under sail, but those are not the sort of holes that I'd try to plug from the outside while under sail.

By the way, I have been thinking with some concern about the placement of a holding tank vent in relation to dynamic waterline. You don't want the thing in your face or near your bow cowl vent for that matter, but the rail is in the water so much that I wonder where you do put a holding tank vent, unless you ran it through the transom and that would not be pleasant when running down wind. :(

...oops off topic.

Groco and I did not discuss which type of bronze these valves are made of, but they do provide a bonding screw, and so now I have to figure out how on my OB Model Ariel I am going to deal with a zinc for these guys. I have a rudder zinc tied to my upper rudder shaft and a rudder shoe zinc connected to my lower shaft though the shoe, but I better search this site for zinc threads, or start one.

By the way, what appeared to be forty year old Wilcox-Crittenden sea cocks on my boat, although they were as green as my new boot stripe, were in great shape. One of them was frozen due to lack of use (a head valve that was capped after the original head was removed). No pink metal at all: solid bronze that looked like new. The yard cut the poor things from my hull, and once they were off, it was apparent that they were like new through and through.

Were I to do it over again, I would have removed, rehabilitated and reinstalled the head sea cocks, and I would never have removed the cockpit seacocks. Although there is a benefit to having 1.5 inch sea cocks on the cockpit drains for sure, I could have replaced a one and one eight inch fitting, and then used a couple of parts plus a Groco full flow hose barb to take me to 1.5 inches from one an 1/4. My point in saying this is that even with very old bronze sea cocks there was no indication of corrosion. On the other hand, corrosion in my rudder fittings and upper rudder shaft were evident. We have a hot harbor. A neighbor lost a rudder due to corrosion a few years back, and yet, my unbonded thru-hulls and sea cocks were just fine. MY Boiat has been in thsi harbor and this slip for at least ten years.

Groco stopped making their rubber plug seacocks in 1992, and I had two of those. Although undersized for my application, they were in perfect condition also. I had just dissambled, cleaned them, and and regreased them before the yard recommened replacement. The solid bronze parts and sea cocks were not bonded to anything, but the bronze was in like new condition.

Hmmmm Bill, I though Marelon was virtually indestructible except by fire. Even the very traditional Dan Spurr has used them, so although they seem somehow out of place on my Ariel. Mr. Spurr put some Marelon Seacocks on his Triton as I recall. See "Spurr's Boat Book". A must read for every Ariel owner.

If you are wondering how green that new boot stripe is, I just repained it today. The original job did not withstand three haulouts in less thn a month. So, take a gander. The green and red are paint of course. The white is pure original gelcoat:

ebb

08-31-2004, 07:48 AM

Current practice is not to bond ie connect your underweter thruholes together. Since you ARE OUR researcher on this subject, maybe you can find substance for this. I believe skippers feel that marinas are so hot that it is better not to connect but to zinc.
[John, on the 'sink me zinc me' thread suczincly explains modern zincing]

I really don't think Marelon can be broke. The broken handle story has been around forever. It may be related to the screw that holds the handle on to the body which has been replaced by a fatter one for a number of years. But I don't know what "breaks."

Marelon seacocks cannot be taken apart for maintenance. The only m. you have to do is grease the ball by taking the hose off inside and outside when the boat's out. Once a year. Maintenance consists of 'cycling' the valve. The dirtier and more virulent your marina the more you turn the handle. Wouldn't this be the case for an alloy valve? Exercising the valve keeps the ball clean.

One Marelon guy says he has never had a problem even tho his valves are rather stiff. The handles are balanced in the sense that they project out both sides of the shaft. He doesn't LEAN on the long side but cups (my description) the handle providing up and down turning on the handle.

If you've forgotten to cycle your seacock for three years and you have live barnacles in the hole, and you use a piece of pipe to persuade the handle to open or close, something has to give. What gives maybe is the center(?) I'm going to check this out because I want to use Marelon on 338.

I have not varified this:
Forespar site talks of a "93 series" a heavier form of thruhull. If I understand it, you not only can get a heavier thruhull but also get one with STANDARD PIPE THREAD. You match the NPT with an NPT valve (not sure if that means seacocks also have that option.)

What this means is that you can get many more turns befor it snugs up. I'm going to call them and will ask. I can't see any reason for a pipethread thruhull going into a pipethread seacock - so they must be talking about the questionable practice of using an inline valve as a seacock. And providing a stronger thruhull with the proper threads.

OK. Just talked with Forespar. Yes the handles can break, cecause they are not exercised regularly and the balls load up. Head discharge seacocks calcify and must be REPLACED periodically. The same is true for sink valves related to what you put down the sink.

The 93 series of SEACOCKS were produced in response to new regs (But by whom didn't compute (ABYC?)
You purchase the seacock and thruhull as a unit. They are pipe-threaded ie both are NPT. The thruhull is pared down till it fits into the seacock depending on backing block height. This has to be the most secure setup ever.

For you guys who insist on alloy, maybe Scott can find out if Groco/Apollo/Spartan have a version of these too. It's a whole new ball game :D

Scott Galloway

08-31-2004, 11:51 AM

Ebb,

I am not sure that I care to find out. In my still very uneducated opinion, it make no sense to have an NPT to NPT connection between a thru-hull and a sea cock. This does make sense when using an in-line valve, but a seacock must fit snuggly and bolt through or screw into its backing plate. The length of the thru-hull will depend on the measurements A + B in the above drawings. So unless they made a series of these thru-hulls in various lengths, one would be in the position of having to cut off part of the NPT fitting on the thruhull and rethread these things.

When I spoke to the Groco rep, we did discuss the NPT to NPT fittings on their thru hull to in-line valve option for above the water applications. He told me that they design NPT threads to turn by hand 2.5 to 3.5 turns. Having more turns is not OK, and having less turns is not OK. Then you get about another three turns mechanically (as I recall) with your wrench.

That makes a total of 5.5 to 6 threads engaged, and that ain't enough turns in my opinion for a below water and below valve application, despite the fact that many marine yards install in-line ball valves on thru-hulls in exactly this manner, and Groco themselves show you the best way to do exactly what they do not recommend which is to hook one of these NPT ball valve to NPT through hulls. Indeed even some surveyors accepot the use of these things as valid applications, and the ABYC may actually allow them (according to Buck Algonquin). However, Groco and many marine writers strongly recommend against doing this NPT to NPT ball valve to thru-hull thing below water, so why design a seacock that replicates this silly use of NPT fittings even if the NPT to NPT joint would be tucked away within the seaock body with all of it's glorious six threads engaged (you hope).

The idea behind an NPT fitting is that the taper in the male and female threads coming together creates the necessary compression to hold the joint together....provided that the joint will not be stressed laterally. And by the way, plumbers are not supposed to even do this NPT to NPT thing below ground in a fuel tank installation. They are supposed to use something called a swing joint to reduce the potential of ground-movement-caused lateral sheer severing these NPT to NPT joints. This taper is a good thing for most plumbing applications. The Groco rep says that finely machined NPT fittings if tightened correctly will hold without teflon tape or pipe dope. Pretty cool, huh? Well yes, but not were there might be lateral forces such as flying bodies, tool boxes or storage containers, boxes of canned beans, or spare parts that ypou might store beneath the cockpit in the vacinity of your cockpit thru-hulls.

Now in a traditional flanged sea cock, a different approach is used: A sandwich consisting of a sea cock flange with backing block on the inside and a thru-hull flange on the outside, fully engaged male and female threads along the full length of the A + B dimension (The depth of the threads in the bottom of the sea cock plus the distance from the top of the backing block to the outside of the hull less 1/4 inch), and lots of bedding compound between all of the invloved parts creates the compression necessary to hold the system together. The NPT Threads in this application would offer no advantage that I can determine, would make installation more difficult, and actually serve to weaken the joint by reducing the number of engaged threads.

Now having said all of that, the Groco rep also advised me that the industry is changing rapidly and this means that using conventinal wisdom is somewhat dangerous without consulting your manufacturer and installer (or yourself) about the design of the parts and the installation procedures and material to be used. For instance, Groco has gone from straight thread thru-hulls to something approximating "bastard" NPS threads and finally at this point in time to their current combination thread, but their literaure doesn't overtly state that. And then there is my developing expertise which is based partly on reading writers who published books that predate the changes in the industry relating to thread depth... and also one manufacturer's strong recommendation with is current with their product.

For another instance, this business of which bedding cocmpound to use and coming to understand the cohesive and adnesive characteristics of various products such as 5200, 4200 and various polysulfides is not that simple. You can download the detailed 3M technical sheets and still not undertand what you are dealing with. I had to call 3M to dissover that:

1. 4200 does not act as an adhesive on bronze, but only as a sealant.
However, getting it off fiberglass is another thing all together.

2. The jury is still out on the interaction between 4200 and certain plastics such as PVC and nylon. 3M told me to test the product before using. Prudent advice, but what are the standards for that test? Does your marine yard know the answer? Do you? Wanna be a guinnea pig?

Back to threads, your installer (or you) could very easily assume that a part has one sort of thread and find that the truth is far different. So consult the manufacturer and your yard before you install. If you are using a yard to do the installation, and if you get the answer, "Because we have always done it this way," then take your boat and sail rapidly to another yard, assuming that your original thru-hulls and seacocks are still installed. It's a bit late to do so otherwise.

Certainly there is no substitute for hands-on experience when it comes to working with boats, but when the manufacturing environment is changing, being up to date with the technology is equally important.

ebb

08-31-2004, 01:34 PM

Like I said, repeating Forespar, Buy the set. Seacock comes with thruhull. Probably comes with printed instructions for the yard manager to follow.

4200 is a polyurethane. I wouldn't use anything but marine polysulfide.

Strangely Forespar recomends any and all brands of marine adhesive including 5200. Will ignore that. but will order a set of the 93 series to see what it is. If you lag in the flange from the top with screws, it may mean you can take the seacock off from the inside. You could replace with a fresh one while under way (and a face full of ocean.)

What you do with the mounting is make sure (if you have the height room inside) that the thru hull fits exactly into the seacock as it comes from the box when it is screwed down to the backing plate - or flattened mound of epoxy. I would do this with any brand of valve, because repair and removal next time becomes easy, and therefor not something likely to be put off.

Scott, we are talking here about a flanged seacock (Forespar 93 series) that has straight pipe threads that engage the thru hull. If you get your A's and B's right, as you say, you will be able to turn that valve right down onto the backing. And have it TIGHT. And it is flanged so just about nothing is going budge it if it gets hit.

5 or 6 turns of matched pipe thread is pretty darn good for pipe and fittings. That is I think one half to three quaters of the threaded male portion (IT IS on the tailpiece that goes into the 1 1/2" Forespar inline valve I have right here. but it only feels right as I'm no engineer.) All the lands and grooves are touching in that small area. That's the advantage of pipe thread - you tlghten with teflon tape - and a little bit more.

The seacock screwed onto a straight thread thruhull is, shall we say, merely interlaced. It is only tight when gooped with caulking, no teflon possible here,
You would be able to go under your boat, and if you hadn't used 5200, 4200 or 3200, theoretically easily unscrew the thruhull. That's why you have so many threads, male and female, makes it unlikely. A NPT straight thread seacock is really held on by the flange fastenings. Believe it or not. Somebody tell me if I'm wrong. :o

Scott Galloway

08-31-2004, 11:02 PM

The Groco 1.5 inch seacock and its male partner a 1.5 inch thru-hull engage a full eleven threads deep within the body of the sea cock where they are hopefully safe from lateral forces. I experimented with the parts today, and eleven threads it is.

Now the question is whether to thru bolt or to "lag the flange down" to the mounting block with screws as Ebb says it. Asssuming a good non-splitting installation with lag screws is there much benefit to taking the thru-hull bolt route instead.

The lag screw method is how my last Groco rubber plug 1.25 inch seacocks were attached. They had two screws each 180 degrees apart. The new seacocks have three bolt holes 60 degrees apart. They were well bedded with lots of sticky stuff and the yard had trouble removing them despite their straight threads. I had to use a very large long handled pipe wrench and a bench vise to free the jagged remains of the severed thru-hull from the sea cock body.

The first photo below shows the Groco seacock with a Conbraco hose barb and a Groco thru-hull. The blue tape marks the part of the thru-hull threads that engage the seacock threads (eleven threads deep).

Scott Galloway

08-31-2004, 11:07 PM

This second photo shows the eager new Groco sea cock raising it's right (and only) arm to take the oath of office as Augustine's new port cockpit drain sea cock, and by so doing replacing the in-line valve hiding behind all that white make-up in the back ground. ;)

marymandara

08-31-2004, 11:30 PM

Hi, Scott--

Thru-bolting with countersunk screws is a pretty simple matter, and I like it a lot because it gives that much more material that would have to fail before the seacock/thruhull could be pushed thru by an impact or an extremely concentrated load.

Extremely concentrated loads can be described as things that shouldn't be happening, like the full force of a jack pad or worse yet a rigid non-free-swiveling pad) cradle's pad...or in some cases, the hull trying to stand on the mushroom head only against the pad on the Brownell trailer...well, any of these forces coming to bear right against the thruhull. If you use countersunk thruhulls especially (which is well worth doing, BTW!), you would want to bioth add some layers of 'glass inside to make up for what you are taking out, and thru-bolt it, as I am inclined to think (may well be thinking wrong, but it's just my gut here) that it would be a wee bit easier to ram one of them up thru the hull. Those three little machine screws might be the difference someday by minimizing the deflection in that spot, you never know.

Even if there is never a problem with a yard crew in too big a hurry, if you sail the boat enough, long enough, far enough...you'll find something to hit or lay up against. Those three little screws and the minor amount of time spent...just seem like cheap insurance to me.

Best,
Dave

Scott Galloway

09-01-2004, 12:42 AM

Thanks for that post Dave,

I think that I understand most of that. It does seem that a flush mounted thru-hull would tend to push deeper into the hull if forced than a mushroom flange. Mine have mushroom flanges. The hull thickness there is about 7/8 inch. I am still weighing the issues in this decision. If I understand you, the three thru-bolts that are inserted in three new holes to be drilled parallel to the thru-hull shaft and sixty degrees from one another would mechanically secure the backing block and seacock flange to the hull to prevent the thru-hull from being shoved from the outside through the hull and prevent it from pushing the block and sea cock back away from the hull with the thru-hull.

However, that requires three additional holes, all of whoich woudl tend to weaken thehulla t that location, and any one of which might leak; and if those bolts are stainless, then don't they become mini-anodes and aren't they vulnerable to corrosion, or should one use use bronze bolts on a bronze sea cock flange? I wonder whether or not bronze bolts would be strong enough for this application.

This straight threaded (NPS) joint (seacock and thru-hull threads) appears to be mostly held together by the bedding compound (my yard uses 4200). The thru-bolts merely connect the seacock flange and backing block to the hull and do not lock the thru hull in place or result in compression of the enagaged thru-hull-seacock threads in any way that I can visualize. So the three thru-bolts would not seem to have any function with the exception of keeping the sea cock from turning (loosening) unless there was a collision or impact from outside as you outlined. Or are you also saying that the thru-bolted option also protects the sea cock-thru-hull joint from an inside foce such as a flying tool box to greater extent than the lag screw option. Do not the lag screws effectively prevent seacock rotation, while the bedded baking block, thru-hull shaft, and the thru hull flange on the outside of the thull insure against such internal impact damage?

By the way, the Wilcox Crittenden sea cock flanges on the head thru-hulls on my boat appeared to have been original 1965. They still had spray paint on them from the original interior hull splatter-paint. They were neither bolted nor screwed into anything. Indeed there were no baking plates for those sea cocks. Someone much have removed and re-bedded them at some point, because they were bedded solely with silicon.

dasein668

09-01-2004, 06:03 AM

and if those bolts are stainless, then don't they become mini-anodes and aren't they vulnerable to corrosion, or should one use use bronze bolts on a bronze sea cock flange? I wonder whether or not bronze bolts would be strong enough for this application.

If you countersink the heads slightly and fair over then they won't be in the water, hence no corrosion. Yes, if you ever need to remove them it is a bit more of a challenge, but not an insurmountable one by any means.

As for material, I would (and did...) go with bronze to match the seacock. True, it isn't as strong as stainless, but with three of them, they are certainly strong enough.

ebb

09-01-2004, 06:13 AM

The reasoning sometimes escapes me.
If those three flange screws or machine bolts keep the installation from turning and keeps the backing block in place as well, then you CAN'T expect the thruhull threads to do the whole job of keeping the valve in place. Depending on goop to do anything but ensure against leaks is not correct. The mechanical fastenings are important even on lucky boats such as yours and Bill's.

If you actually have 7/8s of an inch hull thickness where the valves are mounted (338 has maybe 3/8s) you can't have a deflection problem, and driving a mushroom thruhull in by rock or jack stand pad impossible. Yeah, well, nothing's impossible. But with 7/8" thickness three extra 1/4" holes through the hull there just won't matter at all. What they do is make sure that if your thruhulls dezincify to powder your hoile in the hull is mechanically covered. That would be true if something outside scraped against the mushroom, unlikely as that may be.

To me the problem with the extra holes is having the yard do it. The holes have to be drilled square, they are too close to the big hole to be drilled any old way. The holes have to be drilled from the inside which is cramped. If your yard has only experience with inline valve installations, you may be asking them to do Too much. You may have to trust to the goop and the mild clamping action of the thruhull in the seacock. Don't know that I would have them install a flush thruhull either. 7/8s of an inch? that's amazing

The backing block should be thoroly gooped on also.
Perhaps the silicone caulked valves should be recaulked. Trouble is, nothing sticks to where silicone once was. So the area must be well abraded befor the 42000 is applied. No solvent will dissolve or clean the old silicone out of the fiberglass!

Happy valving!!! :D
Poysonally I would presuade Dave over to do it right!!! :cool:

marymandara

09-01-2004, 09:59 AM

Hmmm...Ebb, you are geographically closer, so I now elect you! :p

Dave

Scott Galloway

09-01-2004, 12:47 PM

I spoke with Groco today. They say that commercial vessels are still required to have thru-bolts (machine screws) through the hull connecting all sea cocks and their backing blocks to the hull, but that most private (recreational) vessels are going with lag screws into the backing block. Groco accepts either approach but specifies that thru-bolts be made of 316 stainless. So it appears that depending on your application and your personal preference you can go either way and still comply with the manufacturer's recommendations. They tell me that teak or mahogany backing plates are OK, and that many blocks are now being made of starboard. They say that starboard works quite well in this application. For new backing blocks that might be the way to go.

Spurr's Boat book discusses using bronze bolts, but Groco says no to that or you void the warranty.

Regarding the head sea cocks that I referred to above, those were original equipment as far as I can tell. Again they were sprayed with that same splatter paint that is on the hull inside all the lockers. I think that a previous owner removed and re-bedded them because they were bedded with silicon. That did no happen in my yard, but somewhere else. Although I have salvaged the sea cocks, and I will clean them up for use as paper weights or some thing, they have been permanently removed from the vessel, and have been replaced with new in-line valves. The new valves are not leaking and seem to be doing just fine. They seem pretty well protected from flying things in their current locations. They yard told me that they would clean the silicon off before mounting the new thru-hulls.

I assume that the same person who bedded those sea cocks with silicon also re-bedded my hull-deck seam with silicon and all of the deck hardware. on the hull-deck seam I used tools initially: knives and scraping tools, and a grout removal tool etc., and then my maintenance log tells me that I used acetone to remove the remaining silicon residue, before I abraded it. Some research that I did told me that sanding silicon on fiberglass or gelcoat merely rubs the stuff in deeper, so you need to clean it with an appropriate solvent first, and then abrade. I re-bedded the seam with 3 M 5200 and the rub rail with 3M 4200.

I filled the screw holes with epoxy and reattached everything. The hull-deck seam repairs that I did in 2002 have been holding well with no leaks whatsoever, and so have most all of the deck fittings, with the exception of the chainplates, which have to be re-bedded from time to time. The only exception is one pesky screw in a cabin top hand rail, and an eye bolt that is part of my lifeline / tabernacle bridle that is inserted through and helps secure a boarding step that I initially bedded with poly-sulfide caulk (Boat Life).

The teak step did not want to conform to the slight curvature on the deck at that location, and it lifted. I replaced the boarding steps on both sides and bedded with 3M 4200. That installation was done in 2003 and it is holding fine with no leaks. So although I agree with you that silicon can be tough stuff to remove from fittings and fiberglass, I have had some success with cleaning the area with acetone, and then abrading the surface.

And finally the yard and I both lost big when one of the through hulls that they installed turned out to have what they interpret as and appears to be a casting flaw. See photo earlier on this thread. That meant a second and finally a third haul-out in August and ultimately led to a decision to replace the cockpit drain system on the port side. I went ahead an arranged for the starboard side to be replaced while we were at it. The yard has been very accommodating to me, despite the fact that that have had two Pacific Cup boats in the yard at the same time. They will be installing my new Groco flanged sea cocks this week for me in place of both in-line cockpit drains valves.

ebb

09-01-2004, 08:41 PM

Even after your seacocks are IN!

NO NO NO! You just can't SAY something like that. You do not put totally different metals together under water.

As to the logic or the b.s. you got from Groco, if it is ok to put screws (lags) in the top, then it oughter be ok to put weak bolts thru the flange and hull.
It is true that ss bolts are stronger than bronze, but holy cow what are you holding on here anyway? This seacock screwed to the thruhull with three bolts is one concentrated bunch of clamping. Stainless Steel is overkill and I think you heard the guy wrong. Maybe ok on a boat that's out of the water like a bass boat, BUT NOT A SALT WATER SAILBOAT - NO WAY!

The difference in strength between bronze and ss in relation to the seacock is insignificant. In the face of all you know about dissumilar metals in salt water why would anyone do such a rediculous thing. I can't be'ieve it.

And I'm through here. Good Luck.

Scott Galloway

09-02-2004, 01:12 AM

Ebb,

Hey, don't shoot the messenger. I just report the news.

There ain't no perfect world when it comes to salt water. You put your boat in it, and it mostly comes unglued, corrodes, delaminates, flakes away and sinks. That's the wherefore of it. That's why when shipping out on a wooden vessel in the 1800s, you wanted to pick one of the newer ones; because there would be more of that vessel left for the return trip. It is interesting that we sailors of ancient boats from the mid 20th century, like even more ancient alchemists are focused on esoteric metallurgy, whereas the hot shots who sail these wacky things with no transoms and no cockpit drains don't give a hoot about thru-hulls. They have forsaken them for speed and visions of momentary weightlessness while falling down the green face of a following sea. We bronze-age sailors trail far behind their wakes, and all the while we are arguing amongst ourselves about relative nobility.

The time worn truths of old were worth following for a time, but at sea, no physical thing is permanent. Human beings once had immutable rules for staying alive: Avoid dissimilar metals for one. Was a time when bronze sea cocks had bronze tapered plugs in them, and they were bolted down by bronze machine thru-bolts. I am a Dan Spurr fan, and I find great comfort in his following his advice, but they don't make the tapered bronze plug sea cocks anymore. Groco even stopped making the rubber plugged ones in 1992. New times mean new metals. 316 stainless is not cast iron. It abides by different rules.

If you are lucky, your new bronze sea cock ball valve will have a 316 stainless steel ball. If not, it will probably have a plated ball made of two dissimilar metals. A manufacturer told me that they consider 316 to be relatively inert.

Despite all of the wisdom to the contrary, their experience shows that the bronze machine screws degenerate much quicker when attached to bronze sea cocks than do 316 stainless machine screws. So, not only is 316 stronger, it lasts longer on a bronze sea cock than bronze itself will. This conclusion was not based on theory, but upon years of actual field experience. It makes me a bit uncomfortable, but the man says that it's true, and he has built, tested, sold, and salvaged them.

So if a sea cock manufacturer wants to condition their warranty on your use of 316 stainless steel lag screws or thru-bolts, it's probably worth considering, or you could decide to ignore the warranty requirements, or give up metal sea cocks altogether and go with Marelon for that matter.

Having taken a look at the photos of your boat, do I see a hint of modernity in the opening of your transom, and also below deck; those cockpit drain thru-hulls are above the static water line are they not? Are you building a secret racing sled there? The first Ariel ultralight?
:D

in the photo below: The ultimate cockpit drain

Scott Galloway

09-09-2004, 11:59 PM

Here is perhaps the most convincing reason that I have yet encountered to thru-bolt your flanged sea cocks....and implicitly another good reason never never to install one of those in-line valves in your boat in-lieu of a sea cock. If your boat is in a yard that alleges that in-line valves are sea cocks, you now have a reason to tell them why the two are different, and why you are sticking with Linn and Larry. The quote below is courtesy of Linn and Larry Pardee's marvelous web page:

http://www.landlpardey.com/Tips/Tips_2002_November.html

This post was dated Nov 2002:

Proper sea-cocks

"One of the jobs we have done at Mickey Mouse Marine this season, was to install a new marine toilet in a clients boat. We inspected the sea-cock and found it was, like many that are being used today, not connected in any way to the hull, with only the threaded portion of the thru-hull fitting connecting it to the boat. It was a sort of fortunate/unfortunate story. Unfortunately electrolysis had gotten to the thru-hull and it crumbled as we tightened the hose clamps because it was the only thing securing the sea-cock to the hull, if we pulled on the sea-cock handle to close it, that too would have broken loose. Fortunately the boat was dried out on our tidal grid and we could fix the situation before water poured in. But it reminded us again that this type of arrangement is potentially disastrous. Not only can electrolysis cause a failure, but a good whack from shifting gear could snap this connection. Check your sea-cocks to make sure they are bolted to the hull in such a way that should the thru hull fitting fail; you can still close the valve and keep water out. A very good and affordable proper sea-cock is made by Groco in the US."

Personally I am starting to see the wisdom in Ebb's desire to have no holes whatsoever below the static waterline.

Scott Galloway

08-04-2010, 10:56 AM

In 2010, I decided that it was time to try it again the right way. The capable and very professional people at Aquarius Marine in Santa Cruz removed my two Groco sea cocks and two inline ball valves along with all four thru hull fittings. The two seacocks along with three additional sea cocks were installed IAW American Yachting and Boating Association (AYBA) standards. Pre-drilled resin saturated plywood blocks were glassed onto the interior of the hull, and covered with additional layers of glass, and finally a layer of gelcoat. The seacocks were mounted to the resulting raised pads with bronze screws. I decided to have a fifth thru hull installed for the sink to eliminate the "T" in the port cockpit drain. I reasoned that this would prevent an accidental flooding of the cabin due to a blockage in the cockpit drain below the “T”. I now keep the sink drain closed unless I intend to use the sink for something other than a storage bin for items that I can reach from the cockpit. Shown in the photos below are:

1. The port-side cockpit drain before mounting of the seacock
2. The completed raw water line for the head.
3. The completed port-side cockpit drain and separate sink drain

Tony G

08-04-2010, 12:39 PM

Scott,

Good to hear from you again. Way to revive a waning thread!

I have one question about your recent installation and maybe that of the AYBC/AYBA requirments. Are the flanges of the seacocks secured with bolts that go through the hull, through the pad, then through the flange? Or are they fastened through the flange by a screw that merely sinks into the pad (which makes the most sense to me)? I just can't rationalize three extra holes just to mount a seacock. I understand they don't want it to turn, or should I say get turned out of the hull resulting in a big hole. But come on.....if a person does that it is similar to the kid who runs around with a mouthful of marbles.

ebb

08-05-2010, 09:29 AM

Insisted that I wanted a flush thru-hull, nothing sticking out.
Needed a 1 1/2" seacock and decided on the reinforched nylon one.
Convinced self that there were no bronze seacocks made with an alloy that was corrosion free.

A 1 1/2" Forespar seacock is a massive true flanged foot valve.
Its three 5/16" flange bolts are widely spaced and a fair distance from the thru-hole.
Those bolts are common available silicon bronze and imco nearly inert in salt water.

A338's hull in the flat of the bilge aft where I wanted the seacock was only 5/16" thick.
Built up the area with glass mat and epoxy to about 1/2".
This allowed chamfering the thru-hull hole, and chamfering the bolt holes.
The flat head bolt holes were chamfered deeper so that the heads could be covered with putty.
This would allow finding those bolts again in case the installation has to be taken apart.

The Forespar flush head straight thread thru-hull is rather long. It screws into the seacock about an inch or so.
The interior nubs that are used to turn a bronze thru-hull (just inside the head) are molded into the marelon at the far end of the fitting. Couldn't believe it, damned New Zealanders!
I called Forespar about their placement and the guy said that the two nubs were not for screwing the thru-hull in - "they're left over from the molding process." There are four small cut outs around the rim that are supposedly used to turn the fitting. Did they have a tool available? NO!.
But I felt at the time that I shouldn't shorten the thru-hull from what they supply.
That meant I had to build up a thick block of ply padding for the seacock. Almost two inches if I remember. Used pieces of various thicknesses of Meranti glued with epoxy.
But it left me with installing the damn thruhull and pissed at Forespar. Because I had already messed up the bitty recesses with dry fitting.

But this also meant that the flange bolts had a lot of meat to seat in.
And being through bolted and caulked with butyl means that they can be driven out later.
With a massive backing block this turned to be and if the bolt holes are all accessible, we might lag the seacock on from the inside, as Tony suggests. With the large fastening holes in the 1 1/2" seacock we'd be using, what, #16 screws? Plenty of grip. But through bolting is undeniably stronger, easier to remove - and mechanically fastens the backing structure/pad to the hull along with the valve. With any substantial backing the thru-hull hole and the three bolt holes imco don't present a weakness problem.

After the flanged seacock* is installed with butyl tape (which allows squeeze-out but also resistance to complete squeeze-out that would happen with the tube stuff - in theory anyway - that there will remain some waterproofing under the flange after bolting.

The seacock effectively shuts the hole. The thru-hull screws into the seacock independently from outside.
Used a lot of white thread sealer paste on the part of the thru-hull that screws into the seacock.
The long length of the fitting in the hole through the block has tube butly only part way but the flange is seated in the stuff. Didn't seriously cram it full. Fully screwed into the valve with thread paste it won't leak and if it does it won't matter - as long as I have buttoned the seacock in place.

Cut out a crude installing tool from 1/8" aluminum sheet. It extends down into the thru-hull to the nubs and also registers into two of the small cutouts in the rim of the thru-hull. Screwing it in and seating it slightly below the surface of the hull is a piece of cake. Unscrewing it years from now will be a different story.

The bolts holding the valve can thoerctically be driven out by turning the nuts off and using a driver pin to knock them out. Only the heads in the hull are caulked. NOT GLUED. If I have left enough room the seacock could then be unscrewed from the thru-hull inside. You'd have to be on the hard, of course. Then the thru-hull can be hammered out as it is not connected to anything. If I felt that a polysulfide sealant had to be used it'd be only under the head, not on the threaded shank. Would not seat the thru-hull with urethane rubber sealant.

If this works out in practice, we have here a non-corroding system that can be taken apart easily for replacement or recaulk.
__________________________________________________ __________________________________________________ ______
*Using an in-line ballcock valve for a permanent underwater hole in the hull is 100% WRONG. Even if Forespar shows this as an alternative in their literature you must assume that a ballcock valve shutoff on the hull
MUST ONLY BE USED ABOVE THE WATERLINE.
But imco NEVER used this way in any Areil/Commender.
The Forespar guy on the phone defended the ballcock/hull use by saying, 'a lot of builders use them this way'. That doesn't make the cheap-skates right!
I would not have any hole under water that depends solely on the thru-hull for its strength. The threading makes the thru-hull even thinner. IMCO the threads can be considered as SHEERING POINTS that a whack from the side can break. So even a drain above the waterline hidden away in a locker, almost inaccessible, for which you have a shutoff can get broke if it is a ballcock riding on the thru-hull.
Don't think that a hose clamped to a thru-hull drain is very clever either. Hose has tobe supported so it doesn't become a lever arm to break the ballcock off.
[way later edit: Groco (not Forespar) now has a ballcock conversion kit that adds a straight thread flange to the inline valve converting Groco brand ballvalves to a proper seacock.]

What have I missed?
Yeah, I know, keeping it short!:D

tsprat

08-05-2010, 07:22 PM

Hello, Computer sailors,

The magazine professional boatbuilder has a online article from this year, Called the standard for seacocks

Tim

Scott Galloway

08-06-2010, 01:38 AM

I was informed in 2004 by Groco engineering staff that the warranty on their product is valid for either the thru-hull-bolt approach that Ebb described above or the screws-into-the-glassed-on block that was used on my boat.

I didn't wish to have three additional holes per seacock drilled through the hull of my boat. So the bronze screws holding the seacock from turning on its thru hull fitting are drilled into the block, but do not penetrate the hull. This approach works and apparently satisfies the manufacture's installation criteria, which in my case is established by Groco.

The mounting blocks on my boat were created by glassing pre-drilled, resin-saturated plywood blocks to the hull and building up a fillet around the plywood block and a layer of cloth over the block followed by a layer of gelcoat. The seacock is then mounted on the block with three bronze screws that are drilled into the block.

Additionally, I commented earlier that I was informed by the professionals in my boat yard that the seacock installation on my boat meets the AYBC standards. As I understand it, this standard requires the seacock/thru-hull installation be able to withstand a 500 lb lateral impact. I have been informed by people I trust that the installation on my boat was designed to meet that standard.

ebb

08-06-2010, 06:49 AM

Thanks, Tim.
You'll find it in Archives under Attention to Detail.
Type of hose recommended for under water (nothing less than wet exhaust) is also mentioned
and just as important to how robust the installation is.

Steve D'antonio, the writer, has a test I've not heard before.

It's the STAND-ON-IT test.
If you can't stand on any part of your valve, hose and hole-through-hull system
it is not strong enough!

ebb

08-06-2010, 07:36 AM

Just checked back again into Forespar catalog and data sheets. Nothing has changed.
They have diagrams (no photos of actual installations) showing their IN-LINE ball valves used as seacocks.

Thru-hulls have STRAIGHT THREADS. When you buy one it comes with a bulkhead nut.
They show the nut being used inside on a backing block to hold the fitting in the hull. They show this on bottom of hull diagrams. DEAD WRONG.

The in-line ball valve has PIPE THREADS on both sides of the valve.
(Altho I have heard people swear this isn't so.)
When you screw pipe threads onto straight threads they will start jamming almost immediately.
You may get it on about 1/2". By then you are distorting the threads. Could say that the valve is being held on with just a bit of thread since the thread in the valve is truncated, not straight.
The ball valve is in an obvious precarious position. A child couldn't stand-on-it!

When you think of it, you are using a hole liner
which is unfastened and unsupported to hold your bulky turn off valve and pipe - which you probably had to force under stress to get it together. It is ludicrous that Forespar recommends this situation. Grocco also shows this in-line ballcock BS in their literature but at least they print a disclaimer and don't recommend it. Anything to make a buck.

Forespar has a disclaimer that they will not be held responsible for 'improper installation." and I suppose Grocco has also.
__________________________________________________ __________________________________________________ ___
LEAVE THE FACTORY GEAR IN PLACE.
After seeing a photograph in Good Old Boat showing an old ball valve used as a seacock in an article on spring maintenance, Jerry Powlas and I had an exchange of emails. I originally complained that in a national magazine you can't show the general pubic things that are wrong without comment. After some long emails from Jerry, he had this to say:
"Still there would be cases where I would leave the factory gear in place, as I have done with most of the stuff in my own boat. This, even after I could have replaced all of it and handed my insurance company the bill after Mystic was hit by lightning. I could not bring myself to move the openings to make room for modern gear and specs when the buggered old stuff had served without complaint for three decades. Also, since the damage from the lightning was so extensive, the only way I could save poor little Mystic from the wrecking ball, or an auction was to do most of the work myself, Thus, I would have had to remove the old valves, plug the holes in the hull. find an new place for them with more room, bore the holes, mount the valves, and find a way to pipe to the new locations. Withe everything else I had to do, it was an easy choice.
Still,.........I hope I did the right thing. You never know for sure."

A splendid, casual admission of what seems to be a common complacency. The old installations worked for three decades, they are certain to last three more. I found no mention of the photo of the wrong installation in subsequent issues of the mag. So the WRONG installation has been reinforced in the readership as a CORRECT installation.
This may be because a non- US company shows to manufacturers of boats and customers alike wrong diagrams of installations that given the source seem to make it right.
As far as Jerry Powlas' mag is concerned, imco he did the wrong thing.
In terms of his own boat, attitude, money and time ruled his decision not to upgrade and CORRECT when he could have.
Maybe we all do this. His decisions for his boat also compromised the integrity of his magazine, imco!
Maybe you can't DO the right thing - but you must show that you KNOW what the right thing to do is - and WHY.
If you happen to be the publisher of an influential boat mag, what do you do.... gloss over it?
Not the unvarnished truth a subscriber deserves!
A great comfort as the water rises due to a good enough broken valve.
__________________________________________________ __________________________________________________ _______________________
"The world is a dangerous place.
Not because of the people who are evil;
but because of the people who don't do anything about it." Alberto Einstein