I think I know exactly why it happened. We are in Western NY area of the great
lakes. I covered my boat over the winter (loonnng and coollllld) with a blue
plastic tarp, no vents in it but it was not on as tight as a shrink wrap.
In Early February, we had a warm spell where the weather actually got up to the
high 60's for a few days. Then, in less than a day it plumeted back down to
well below freezing and stayed there for a month.
I think that the inside of the boat probably heated up pretty good when it got
warm. I should have opened up the cover and aired out the boat, but I didn't
want the headache of putting it back on.

Next year, if it warms up in the middle of winter, I'm opening the cabin to
vent it. Also, I'm going to put my dehumifier in the cabin with an extension
chord attached so that when it gets warm, I can simply plug it in for a while
to remove the moisture.

The boat's a 1993 and this is the first time I ever had this problem.

Never again!

Wayne