You also get SERIOUS condensation inside the boat. Great for mold,
Actually, no x2:
Condensation is not a real problem, may even be less of a problem in the water compared to on the hard; it is usually colder on the hard, humidity is about the same.
Mostly too cold for mold. In both cases (water, pulled) one has to decide which strategy to use: closed or open:
Closed means everything should be locked, no air vet at all. One has to ensure all humidity is absorbed, usually in some kind of salt.
Open means ventialtion is open, the more the merrier. Dust and dirt will enter, but humidity is ventialed away.