The first layer of the new bottom is 1/4" thick mahogany laid on a
diagonal . The outer layer of the bottom will be 1/2" thick cedar
bedded in 3M 5200 . The 5200 will form a flexible and waterproof
membrane between the two layers .
One challenge in doing a double bottom is that there is no way to
clamp the second layer of planking to the frames while they are being
fitted . A few loops attached to the keel to hold some sticks over the
planks helps hold things in place .