New Fangled Hoses & SEACOCKS!

[ebb]

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]

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/...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]

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.

[Bill]

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.

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]

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.

[marymandara]

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!!!

[Scott Galloway]

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]

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.

[Bill]

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.

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

[Bill]

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 . . .

[Scott Galloway]

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]

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 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.

[ebb]

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]

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/cruisin...ks_169243.html
http://www.boating-forum.com/cruisin...on_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.

(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.

[Scott Galloway]

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.