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cxz · 12-07-2023, 03:19

I've been changing some seacocks and thru hulls for the first time and wanted to get some thoughts on my process which I don't feel was done entirely professionally. I've made the upgrade to TruDesign and had to redo the galley sink thru hull twice now after I realized that the thru hull fitting needed to be 1 step up to match the hose sizes (wish they warned about that).

In particular, this thru hull for the galley sink had me thinking a bit. Some concerns:
1) I didn't put enough Sika 291 on the threads for the thru hull fitting. I figure it should be OK though. [pic 1, 3]

2) I stupidly decided to also put Sika on the plastic washer, which isn't a problem in itself, but when I tightened the nut I saw the Sika shifting a bit underneath the washer since it was now adhered to the nut. Would that have broken the seal? [pic 5]

3) I also tightened the nut 1/4 of a turn, not 1/2 as the manufacturer recommends since it was getting tight and they do mention not to overtighten. [pic 8]

I've attached some pictures and wanted to know what you thought. Am I just over-worrying? I feel like I put sealant where I shouldn't have and a bit too little where I should have. I don't think it's a huge issue and it should hold up OK, but it could have been done better.

Bowdrie · 12-07-2023, 07:27

In pic #9 it appears that you filled-up all the internal threads with sealant.
Whatever male thread is screwed into those female threads will simply push most of the sealant ahead of it and form a big ring of sealant right where the rotating ball is in the valve assembly.
You put sealant on the male threads only.

cxz · 12-07-2023, 07:48

Quote:

Originally Posted by Bowdrie

In pic #9 it appears that you filled-up all the internal threads with sealant.
Whatever male thread is screwed into those female threads will simply push most of the sealant ahead of it and form a big ring of sealant right where the rotating ball is in the valve assembly.
You put sealant on the male threads only.

Hmmm that does make more sense. I will do it that way next time. As for the toilet seacock, I did the same and the ball valve still seems to turn. So I hope that this is still ok, else a pointy stick up the hole and some light jostling might be required I guess.

CharmCityBoater · 12-07-2023, 08:06

I think you have done a pretty good job. I always worry about the through-hulls I replace. Will they leak? Did I do it properly? A few years back I saw some of the employees at a boat yard replacing through hulls. They cut the old ones out with a grinder, spent 2 minutes roughing up the hole and surrounding fiberglass and quickly inserted a new mushroom fitting and valve inside the boat. Did not care if there was still bottom paint showing, if it was free of dust / dirt, if the hole was a little too large, if it was tight enough, if it had enough sealant... I asked one of the guys about it and he said they can replace one in 10 minutes and as long as you have enough sealant to cover the gaps it won't leak.

I just replaced a bunch of my through hulls with Tru-Design as well (Will not go back to bronze). I used epoxy to bed the mushroom fitting in the hole. After setup some of the inside nuts would turn 1/4 turn, some more, some less. Just made sure they were tight. I used 3M 4200 on the threads to install the ball valve. I did not use any sealant on the base of the load bearing collar. I did sand to bare fiberglass to ensure a tight bond.

I did create 1/2" fiberglass backing plates for the inside of the hull. Basically, laid up 10 layers of 1708 cloth with epoxy resin and cut out round backing plates for all my through hulls. My hull is close to an inch thick fiberglass but wanted that extra strength of a fiberglass backing pad. The old ones were plywood.

Yours look fine. I would not overthink it too much. Yard workers get away with much more shotty jobs... Just make sure they do not leak when you are in the slings of the travel lift and they should be fine. My $0.02

capt jgw · 12-07-2023, 08:43

Quote:

Originally Posted by Bowdrie

In pic #9 it appears that you filled-up all the internal threads with sealant.
Whatever male thread is screwed into those female threads will simply push most of the sealant ahead of it and form a big ring of sealant right where the rotating ball is in the valve assembly.
You put sealant on the male threads only.

And sparingly. You only need a tiny bit to fill the threads.

George_SD · 12-07-2023, 08:43

1) clean the surface area more
2) I would put less sealant, but then won't be cutting it around as not to disturb it
3) don't put sealant on threads inside the valve
4) just follow the recommended installation manual instructions.

Ryban · 12-07-2023, 10:21

This video seems to have applied sealant on the female threads as well:

https://www.youtube.com/watch?v=XFFW8h6CHEg

Fiberglass backing plates sound like a great idea, and I'll want to so something similar when I replace mine. Perhaps just G10 cut out. My previous owner used wooden blocks which have started to rot away.

CharmCityBoater · 12-07-2023, 10:29

Quote:

Originally Posted by Ryban

Fiberglass backing plates sound like a great idea, and I'll want to so something similar when I replace mine. Perhaps just G10 cut out. My previous owner used wooden blocks which have started to rot away.

G10 is hard to cut with a hole saw or jig saw. It is also more expensive than just making your own. Even better, find an old boat the yard is cutting up to get rid of. Use some of the flat fiberglass and a hole saw. Free.