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Is using 3M 5200 selant too strong to water proof cockpit?

JamieB

.
Aug 1, 2021
29
Beneteau 400 Loano
So we've had some leaking into the rooms via what we think is old caulking leaking in the centre cockpit. my question is removing this and applying 3M 5200 a good idea or is this too strong?

it's around the area shown in the pictures. anyone got any experience with it?

I've heard it's for places where you don't expect there to be any movent in the future so don't want to make a mistake.

thanks for the help and guidance.

J
 
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
5200 is primarily an adhesive, not a a sealant or caulk, thus it would be a poor choice for sealing leaks.

In the 3M line 4200 or 4000 might be a better choice depending on the nature of the gap being filled.

To seal a leak the sealant needs to be flexible and be able to stretch due to boat's movement and thermal expansion and contraction. 5200 is not as flexible as 4200 or 4000 which have good adhesive properties and good flex and stretch properties.
 
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
This is a "right tool for the job" thing. As others have said, 5200 is an adhesive, not a sealant. If you want to use an adhesive, there are others on the market which, unlike 5200, remain somewhat flexible.
 
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JamieB

.
Aug 1, 2021
29
Beneteau 400 Loano
5200 is primarily an adhesive, not a a sealant or caulk, thus it would be a poor choice for sealing leaks.

In the 3M line 4200 or 4000 might be a better choice depending on the nature of the gap being filled.

To seal a leak the sealant needs to be flexible and be able to stretch due to boat's movement and thermal expansion and contraction. 5200 is not as flexible as 4200 or 4000 which have good adhesive properties and good flex and stretch properties.
I'm not seeing pictures?

dj
 
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
For that application 4000 or 4200 would be appropriate. There is a UV stable 4000 or 4200 (can't remember which off hand) that would be best as it will not yellow or turn brown.

To do the job properly, it will be necessary to remove the old caulk and clean the surfaces. The seal will be better if the pedestal can be raised a few inches and the caulk applied underneath the pedestal. there is probably a flange that allows the pedestal to be bolted to the cockpit sole. More work and effort than running a bead of caulk around the joint but with a better outcome.
 
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JamieB

.
Aug 1, 2021
29
Beneteau 400 Loano
For that application 4000 or 4200 would be appropriate. There is a UV stable 4000 or 4200 (can't remember which off hand) that would be best as it will not yellow or turn brown.

To do the job properly, it will be necessary to remove the old caulk and clean the surfaces. The seal will be better if the pedestal can be raised a few inches and the caulk applied underneath the pedestal. there is probably a flange that allows the pedestal to be bolted to the cockpit sole. More work and effort than running a bead of caulk around the joint but with a better outcome.
ah thanks so much for the advice. the table screws are loose as well so might be able to big two birds with one stone.
 
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
ah thanks so much for the advice. the table screws are loose as well so might be able to big two birds with one stone.
And make sure the pad eye is properly secured and backed up. Might as well caulk that too. ;)
 
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Likes: JamieB
Aug 2, 2009
465
Catalina 315 Muskegon
Agree that 4000/4200 would be the right choice. Also agree that removing all the old caulk, and removing the pedestal is the best way to ensure that you're getting a good seal (definitely how I'd do it). Not fun removing it, but having water migrate into your core is even less fun.
 
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May 14, 2019
22
CORONADO 23-2 Home
if you ever want to remove it, I would not use 5200 it does indeed stay flexible, but it is very very strong and wood and fiberglass will usually yield before it does... 4200 would be a good choice, or just go butyl tape, easy, good seal and easy to replace down the road.
:)
 
Jun 14, 2010
1,726
TBD Looking for my next boat CT
if you ever want to remove it, I would not use 5200 it does indeed stay flexible, but it is very very strong and wood and fiberglass will usually yield before it does... 4200 would be a good choice, or just go butyl tape, easy, good seal and easy to replace down the road.
:)
+1 on the butyl. It would provide the best seal and flexibility. You’d never have to redo it, and you could still remove the pedestal easily for service if needed. Second choice would be 3M 4000UV.