New Fangled Hoses & SEACOCKS!

[Scott Galloway]

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]

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]

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]

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]

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]

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!!!
Poysonally I would presuade Dave over to do it right!!!

[marymandara]

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

Dave

[Scott Galloway]

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]

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]

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?


in the photo below: The ultimate cockpit drain

[Scott Galloway]

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]

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]

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]

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!

[tsprat]

Hello, Computer sailors,

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

Tim