Through Hull Sealant

[lifeofreilly57]

Greetings
I am in the process of removing some though hulls, that is in another thread in this forum so I won't go into that subject.
Now that the old ones are coming out (slowly) I'm ready to install the new though hull housings.
Whats your choice for sealant on through hulls? How easy/hard was it to use? How long has the through hull been installed? Any failures?
Please don't say 5200, the current ones were installed with 5200 and have been a bugger to get out without damaging the hull material.
What's your number one choice in an application for a depth/speed sensor?
All suggestions are appreciated, except for 5200 unless you have a really good case for using it.

[billknny]

I'd suggest you go with a polysulfide caulk. LifeCaulk is one readily available brand.

It is adhesive after a fashion, but with none of the serious issues you get with a polyurethane... like 5200.

I have never seen or heard of a properly installed through hull fitting leak because the sealant failed.

[lifeofreilly57]

OK, I got the fitting out without too much trouble with a combination of solutions.
First I soaked it with the marine release agent for a couple days.
Then made a puller out of scrap 2x4 blocks, one on top of the fitting inside the hull and another outside using scrap blocks as spacers, this pulled the fitting out to the surface of the inside of the hull without much fuss.
Then I used a gear puller to hook the edges of the fitting (brass) and a piece of scrap steel tubing across the 2x4 spacer blocks to screw the gear puller against.
I needed to use the puller until the last 1/4" of the fitting was just about out, the 5200 did not want to let go.
No damage to the hull or glass, only a little damage to the fitting flange by the gear puller, which could easily be tapped out with some light hammer work.
Now if I can just get that auto pilot ram to fit in it's tight space.....
The list goes on.
Thanks for all the suggestions and feedback, I appreciate it. Like usual, it's a combination of strategies that works, since each situation is unique.

[Mr B]

A thru hull is usually a permanent fixture, How often do you remove a thru hull,
Being easy to remove would also tend to be a leak some time in the future,
Thru hulls are some thing you dont ever want leaking,
Ease of removal doesnt enter the picture.

[jgbrown]

Originally Posted by lifeofreilly57

OK, I got the fitting out without too much trouble with a combination of solutions.
First I soaked it with the marine release agent for a couple days.
Then made a puller out of scrap 2x4 blocks, one on top of the fitting inside the hull and another outside using scrap blocks as spacers, this pulled the fitting out to the surface of the inside of the hull without much fuss.
Then I used a gear puller to hook the edges of the fitting (brass) and a piece of scrap steel tubing across the 2x4 spacer blocks to screw the gear puller against.
I needed to use the puller until the last 1/4" of the fitting was just about out, the 5200 did not want to let go.
No damage to the hull or glass, only a little damage to the fitting flange by the gear puller, which could easily be tapped out with some light hammer work.
Now if I can just get that auto pilot ram to fit in it's tight space.....
The list goes on.
Thanks for all the suggestions and feedback, I appreciate it. Like usual, it's a combination of strategies that works, since each situation is unique.

Next time you may find the following easier:
Get the nut of. Chop the thru hull with a grinder so it's reasonably close to the hull(1/2" is good) Next get a good thin metal blade in your reciprocating saw, chop the T-hul in 3-4 places around the interior(like spokes on a wheel until you can see glass. Drive the wedges of T-hull together in the middle breaking most of the sealant bond then drive the remainder out.

For sealant I like 3m4000UV. Better sealant(not runny) faster cure, and multi-purpose. You just need a good sealant, not a strong adhesive(5200)