[Public-list] Coamings

[Roger L Kingsland]

My buck 3.80 on sealing the combings.

In the sealing of buildings, it is common practice to install a foam "backer
rod" in the gap between the two surfaces to be sealed before installing
sealant (caulk).  The backer rod, set just below the dark side of the caulk
allows the caulk to form an hour glass shape in cross section (your finger
on the top, exposed surface forms the other side of the hour glass) which
insures a good, flexible, long term seal.  Therefore, a gap (1/4" is good)
between the materials is actually desirable.  If there isn't a gap, the
sealant will be too thin and crack (in shear) rather than flex under
differential movement between materials.

When I put my combings back on the boat, I plan to add a 1/4" thick shim
about 5/8" below deck level (and another at the bottom of the combing to
keep it "straight"), press a 3/8' diameter backer rod on top of that then
caulk what's left and run my finger along deck level to finish her off.
This might work.

Roger



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