bottom caulk?

[kd]

We cotton caulked the bottom our cedar-planked Prudence below the water line. What next? Can anyone suggest a product for caulking over the cotton? Interlux seam compound for underwater?

...and then bottom paint?

[RGM]

Paint the cotton and seams with your bottom paint prior to paying your seams with the Interlux compound. Make sure your cotton is well set(firm and to the back of the seam). Let the paint dry a bit or at least get tacky before paying the seams. Good luck.

[uncas]

After that...and I hope no one is looking...A cover of red lead paint...to seal everything in.
I do this a lot...

[David Conard]

After setting the cotton, I brushed in a liberal coat of red lead (from Kirby's) and then used Interlux brown seam compound. I did use BoatLife (not the stuff with silicone in it) to pay the seams in the deadwood, and the lower garboard seams. My boat's keel and deadwood are white oak which in the cold dry of a Vermont winter moves around alot more than the cedar planking.

[MuddyFeet]

You can't go wrong with the suggestions given above. There has been a lot of discussion on the forum regarding topic, as a search will show. For a good summary of seam compound products, look also at this article reprint: http://www.bosunsupplies.com/sealants.cfm

[arabiansea]

I'm not familiar with a "Prudence" but I have caulked a few cedar hulls. If this is a larger boat, then the amount of time out of the water will mean the seams are wider and the need for a flexible compound is greater. So that the exess will squeeze out and not force the planking from the framing when it swells.

I preffer the 2 part BoatLife but if you aren't used to 2 parts then use the 1 part. Stay away from the Inturlux seam compounds. They harden and when the hull is working in a seaway you'll need the flexability otherwise you'll need to hualout after each blow, and recoat those seams just to stop the weepage. Major PITA. So leave the Interlux for those that admire thier boats as they sit on the trailer.

[imported_Jimmy]

A very important step that several people have mentioned is the red lead primer on top of the cotton. If you do this then polysulfide and other goops will probably not stick well so the next step is to use a traditional seam compound.

If your boat moves enough in a seaway that you have to redo the seam compund then you have bigger problems than using the right seam compound. Traditional seam compound in a traditional boat is a good way to go. If the boat is more in the workboat direction, there are cheaper, less attractive options. A lot of people around here use cement below the waterline on larger boats (mostly fish boats).

[TimothyB]

The Interlux seam compound is oil based, as far as I recall, and in the application instructions they specify to prime the seam with bottom paint before applying the brown compound.

http://www.interlux.com/