I found water in my hulls, after the boat had not been on the water since '97, and with no recent snow or rain, the boat has been covered with a tarp. This was due to the condensation, and the only solution is ventilation.
I had previously installed hull ports in both hulls, but had closed them tight, not thinking about the condensation. I just removed the lids, and overnight the water dried up. I figure to leave uncovered till Spring and let dry all Winter. Makes me wonder how much water is absorbed into the foam core? I hope to dry out and avoid further delam of the core! Freezing that moisture in the foam can't be good for the hull!
For those with out ports, I would wonder about using a small fan with a tube attached that could be stuck into the drain holes, to inject air into the hulls. The tube would need to be pushed to the bow of the hull, so to get air circulation the full length. I don't know whether a small tube could get enough air in to do much good? But if the fan was left running continuously, it might help. TnT