When we cruised Mexico aboard Camille we had very few issues with moisture and condensation. Baja is a desert and the windows were always open to keep the air flowing. Here in the Pacific Northwest we have the opposite: rain, cold, closed windows. A cushion resting against the hull will be damp in no time. The diesel heater is helping to dry things out on the hook. When we are at the dock we use space heaters pointed at enclosed spaces.
One of the biggest moisture collectors is the bottom of a mattress after sleeping on it for a night. On Camille we had a (rather expensive) Froli system under our mattress — mainly to try and give our thin mattress a little more bounce. On Limerick we have a great mattress but nothing to deal with the condensation. So we picked up some hypervent which came highly recommended by a great online group of women sailors I am part of. We cut it (quite easily with scissors) to also come up the edges of the mattress where it touches the outside hull.
It is working out fairly well. The bottom of the mattress is staying dry. Now the moisture has moved below the hypervent and seems to be drying as the day progresses. I had expected no condensation, but I guess that is a bit much to ask in this climate. We’ll be purchasing more hypervent for the V-berth.