which caulking is acceptable

995jim

Seaman Apprentice
Joined
May 27, 2016
Messages
45
Hi. when I go to reinstall screws to attach a bracket on the outter face of my transom on my fiberglass boat which of these caulking choices is best to leak seal
butyl
rtv silicone
marine silicone
thanks jim
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,652
Hi. when I go to reinstall screws to attach a bracket on the outter face of my transom on my fiberglass boat which of these caulking choices is best to leak seal
butyl
rtv silicone
marine silicone
thanks jim
3M 4200FC
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,340
Boat caulk by life caulk

Never sillycone. Butyl is for windshields, hatches and RV roofs
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,340
FYI, look up the practical sailor caulk test results. The 3M products failed in their teating
 

Pmt133

Lieutenant Junior Grade
Joined
Jan 6, 2022
Messages
1,001
I like boat life and their life caulk and seal. I recently bought a few tubes of the caulk. I had one that wouldn't adhear worth a ****. Peeled off like painters tape. The other tubes (which I then had to test because of the first one) was fine. First time I ever had an issue like that. It was an older lot number but still within usable range so just check that before you commit.

Are these through hull or blind holes?
 
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