[Alberg30] cockpit coamings

[EddieDiver at aol.com]

The weakest shaped caulked joint is the fillet-shape or triangular-shaped. 
That is the shape one gets when they caulk between the vertical coaming and 
the horizontal deck. A triangular-shaped bead will begin tearing at the 
hypothenuese (sp?) when it contracts and expands.
The best shaped caulked joint is the butt joint. This would be between the 
vertical coaming and the small vertical edge of the deck. For caulking to 
work effectively, only the 2 opposite surfaces should be in adhesion. The 
top, exposed surface and the bottom surface should be free to contract and 
expand. The way to do that is to fill the bottom of the vertical caulking 
with a compressed sponge-neoprene or sponge-foamed polyethylene. I should be 
1-1/2 times thicker than the finished joint width.

I would suggest putting the sponge material, approximately 3/8 thick, 
vertically between the deck edge and the coaming. It will be squeezed down to 
approx. 1/4 inch thickness when you install the fasteners. Because you want a 
finished square section of caulking, keep the top of the sponge down 1/4 inch 
also. Fill the 1/4 by 1/4 resultant opening with the sealant. Try not to have 
a fillet-shaped caulking bead. I too like the one-part polysulphides and 
one-part polyurethanes. They will adhere to each other when "touching -up"; 
silicones will not adhere to each other. Ed. Schroeder #303 Emotional Rescue.
 +---------------------------------------------------------------+
 |  Boatowners Mechanical And Electrical Manual by Nigel Calder  |
 | http://www.amazon.com/exec/obidos/ASIN/007009618X/alberg30-20 |
 +---------------------------------------------------------------+

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 1047341963.0