Thru hull sealant

Robo

Lieutenant Commander
Joined
Feb 27, 2012
Posts
118
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Location
Southern R.I.
Boat Make
1985 31' BHM
I am changing out some above waterline thru hull fittings. The boat is cored, penetrations decored and glassed up. With over an inch of contact on the thru hull fitting, the sealant will have plenty to hold to. I want to be able to remove the fitting down the road. What is the best stuff to use?

Robo
 

F/V First Team

Admiral
Joined
Jan 10, 2012
Posts
6,146
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Location
Narnia
Website
www.otisenterprisesmarine.com
Boat Make
Northern Bay 36 - Modified
Rule 301 clear elastromeric sealant

202b7d10b4b00065469cdc9abd7ee629.jpg
 

nickyp

Captain
Joined
Nov 3, 2012
Posts
792
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Location
bermuda
Boat Make
20ft dyer
i've used 3m's 4000 uv resistant sealant, which is billed as an above or below the waterline sealant that can be used for cosmetic purposes too. It's too bad that it does NOT stay cosmetically sound.
i know this does not really answer your question, but i just wanted to take this opportunity to express my disappointment with this product, and see if any others have had similar experiences.
it seems to break down in the sunlight. Initially it is pure white, and seems like it will be tough. i have used it as cosmetic beads, and also bedding things that where the thin white bead would look good, but didn't want the anti-paint headaches of silicone.
HOWEVER, this product does not stay white, and seems to actually break down in the elements. 4200 is a good product, but any trace of it will discolour in the sun as well. but it doesn't break down like the 4000 does.
i just want everybody to bear this in mind, and not be bitten in the ass by this product. 2 years ago i put in a fiberglass cockpit floor that some place in florida makes for bertrams. we dropped it in and fastened, and had to fill a varying 1/4" to 3/8" gap in the factory flange. silicone would have worked well. but i used this "premium cosmetic sealant with uv resistance" and when the boat came up this week the bead looked awful.
quite a rant, i know. so i would use what all these guys reccomend.
unfortunately we are limited as to want we can buy off the shelf, and when we order sealant in bulk, they always send their old stock to bermuda :(
 
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