Years ago, the local Whaler dealer joked with me and said the only "dry" Whalers are the new ones on the showroom floor.
Here's one of the latest ones I've been involved with , and Outrage 18. The original bow pulpit had a leak through the deck and the large foam area under it absorbed a significant amount of water and froze over the winter causing the fiberglass to buckle and bow. The entire area had to be cut out, gutted, refoamed with two-part polyurethane 4-lbs closed-cell foam, and glassed over. This is demonstrated in Figures 1 to 7 below.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
The foam had significant water content and you could squeeze it out like a sponge.
Figure 7
Perform an annual inspection of all mounted hardware and fasteners, and especially the brass drain tubes as saltwater causes them to corrode.
I feel that wet foam in a Whaler is far worse in the North where it will undergo many freeze-thaw cycles causing other damage. Wet foam that undergoes freeze thaw cycles will compromise the Unibond between the foam core and fiberglass skin.
D-