PLUGGING UNUSED THRU HULLS??

[geoleo]

i AM GOING TO CHANGE THE 10 oem METAL THRU HULLS AND BALL VALVES with marelon ones ON MU 1990 bENETEAU 41s5. i ALSO PLAN TO CLOSE OFF 2 UNUSED THRU HULLS /VALVES. Anyone here know a good switchable safe fitting to do this with? Thanks.

[Orion Jim]

Originally Posted by geoleo

i AM GOING TO CHANGE THE 10 oem METAL THRU HULLS AND BALL VALVES with marelon ones ON MU 1990 bENETEAU 41s5. i ALSO PLAN TO CLOSE OFF 2 UNUSED THRU HULLS /VALVES. Anyone here know a good switchable safe fitting to do this with? Thanks.

Unclear what you mean by a “switchable safe fitting”.

[rwidman]

The simplest way is to remove the seacock and cap the thru hull with a threaded cap. You may need to find one with straight, not tapered threads.

Or. you can leave the seacock and cap the outlet side.

In either case, use bronze or Marelon.

[geoleo]

Originally Posted by Orion Jim

Unclear what you mean by a “switchable safe fitting”.

I mean a fitting with no hole and threads for a nut that will not die from UV.

[geoleo]

Originally Posted by rwidman

The simplest way is to remove the seacock and cap the thru hull with a threaded cap. You may need to find one with straight, not tapered threads.

Or. you can leave the seacock and cap the outlet side.

In either case, use bronze or Marelon.

That still leaves a old thru hull with hole in hull/or a ancient corroded useless so called seacock which is actually a Italian made multi metal frozen ball valve.

[Manateeman]

We just finished removing all our Forespar Marelon seacocks.
We installed Groco adaptor plates and new ball valves.
Marelon seacocks were the worse mistake we made building this yacht.
Forespar does not stand behind their Marelon products.
To see how to install the Groco adaptor plates, go to the Marine How To web page. A great guy who could use a small donation.
You could cap the Groco but we would use glass in epoxy if you are sure you and maybe the next owner, would never need the seacock.
Thru hulls are usually straight thread and caps are tapered. Mixing threads is not a good idea even if it’s just a cap. A thru hull is not a seacock. Supported ball valves, such as Tru Design, are not attached to the hull. We have no use for them. Some boatbuilders use them because they are cheap and quick to install.
You get what you pay for in boats. Groco will last a lifetime keeping the sea out.
Happy trails to you.
Captain Mark and his manatee crew of professional boatbuilders.

[deblen]

Originally Posted by geoleo

i AM GOING TO CHANGE THE 10 oem METAL THRU HULLS AND BALL VALVES with marelon ones ON MU 1990 bENETEAU 41s5. i ALSO PLAN TO CLOSE OFF 2 UNUSED THRU HULLS /VALVES. Anyone here know a good switchable safe fitting to do this with? Thanks.

Suggest you first read everything in this link regarding seacocks:
Cheers/Len
https://marinehowto.com/category/plumbing/

[jooa]

I had 5 unused thruhull holes glassed over a few years back and have never regretted it. Benefits of this are no chance of having an accident with having something heavy collide with the old remaining thruhull stem. Also gave me much more stowage in the locker area because there was no longer a thruhull stem in the middle of it.


JC

[stormalong]

Manateeman is still upset about a problem that occurred over 30 years ago. Forespar had weak handle to ball shafts that could snap and Forespar would not cover them under warranty.

31 years ago, when I bought the boat I have now, two of the builder installed Marelon ball valves had broken handles. I had the discussion with Forespar back then and replaced the two with same but redesigned Forespar Marelon ball valves. They did not make the flanged seacocks back then. I have the same ball valves in use today - still working fine. I have only lubricated them - no further maintenance.

I have 13 thru hulls. Over the years I have replaced about half of them with Marelon seacocks. None have ever failed. Mine are all flush - an option for builders that could place plastic plugs in the mold to form a recess for them. I have also added flush thru hulls in new locations and had the flange turned down to just a 45 degree lip. Still, no failures in 31 years on anything.

I also have removed and plugged a few thru hulls. Glassing over the old holes is easy and pretty fast. I have written about that in the past and won't repeat the whole process. I will just say that this is not a structural repair and there is no need to grind out a twelve to one ratio taper to patch. Just grind to clean glass and a 45 degree taper on the outside and a good inside patch and you are good. Have done a few and you could not find the patched holes from the outside. The show on the inside since I did not paint over them. Some of these were done over 20 years ago.

One more thing. When I removed old thru hole fittings I did destructive testing on them. Hammering them while sitting on concrete convinced me that I do not have to replace the ones still in use.

[vpbarkley]

Marine East sells "mock thru hull fittings".

These are thru hull fittings minus the thru hole.

Link: https://www.marineeast.com/a_sch/sch...d=05&pid=05_04

[Manateeman]

Forespar 849 flanged Seacock ( not ball valve) are still being sold today not 30 years ago. These are the seacocks we removed. There is no way to lubricate the surface of the ball facing the ocean unless you haul the boat. They freeze open and there is nothing you can do about it. The Groco plate let’s you change the ball valve or thread a cap onto it. You’ll get wet it you won’t be faced holding a broken handle with a seacock frozen open. If it freezes shut, you no longer have seawater say to your engine.
My opinion is based on 60 years of professional boatbuilding and an admission using Marelon was a huge and very costly mistake.
Captain Mark

[stormalong]

Manateeman: The idea is to lubricate them before they seize. No need to lubricate outside of ball. Just close seacock, remove hose and water. Paint inside of ball with teflon grease and re-assemble. Some people use vegetable oil.Then open and close the valve a few times to move the grease around.

[Startracker]

Originally Posted by geoleo

i AM GOING TO CHANGE THE 10 oem METAL THRU HULLS AND BALL VALVES with marelon ones ON MU 1990 bENETEAU 41s5. i ALSO PLAN TO CLOSE OFF 2 UNUSED THRU HULLS /VALVES. Anyone here know a good switchable safe fitting to do this with? Thanks.

Marelon would be my last choice.
Bronze thru-hull to a flanged adapter plate, groco etc. Then a good quality bronze ball valve. For ones I know I won't be using, I lubricate well with a grease, preferably the old formulation with PTFE from Mercury, I think it used to be called 2-4-C but my memory is foggy. In any case, I heavily coat ever part of the inside, the ball etc and work it a few times, squishing the grease around in between so it's well packed, close it and coat both faces of the ball very liberally with yet more grease. Then install a male threaded bronze plug in the top of that, close the handle and wire it shut with stainless safety wire. I'm a belt and suspenders kinda guy for unused fittings. Having both and I sleep well. Then if I ever want to open it up again, simply undoing the male plug, screw in a hose fitting and I'm in business.

[moseriw]

Originally Posted by stormalong

Manateeman: The idea is to lubricate them before they seize. No need to lubricate outside of ball. Just close seacock, remove hose and water. Paint inside of ball with teflon grease and re-assemble. Some people use vegetable oil.Then open and close the valve a few times to move the grease around.

Hmm... my Groco's have lubrication nipples. OK it is an extra but lubricating them once a year works fine.

Don't think that vegetable oil is a good choice as it will be eaten up by the "sea monsters" on the outside and will harden on the inside.


And I did not use the flanged Grocos as they are incredible expensive and no one knows why. It is not the make, it is just the greed that makes them so incredible expensive. And I do not see the point that someone throws a 100 lbs something on the seacocks to destroy them.

[sinnerman]

I just did the opposite. I installed Groco bronze thru-hulls with a bronze flanged adapter, Groco composite adapter plates which you bond to the fiberglass hull then attach the flanges to with bolts, and Groco in-line ball valves (IBV).

I was torn between installing the FBV or "Flanged Ball Valve, which has the valve and ball as a single unit. It is stronger and has a grease fitting. However, if the valve fails (seizes) you need to pull the boat out of the water to replace the unit.

With the Flanged adapter and separate ball valve, you can just spin on a new replacement valve.

Groco is not cheap, but I think that they have the best quality..

There were some plastic thru-hulls previously installed below the water line. They snapped off when we went to remove them.

My two cents..

Cheers