From 3/16 to 7/8 inches
The layup on the sides is a little less than 1/4 inch, increasing to the bottom around the keel at a little less than one inch on our '77 model.But there are reports of significant variations in manufacturing through the early 80's.Anyway, the advice to glue down a level wood block is the right way to go. By the way, our boat has a glassed in shelf under the forward end of the quarterberth.DavidLady Lillie