Went skiing today with a mates boat, took the cover off mine to get my skis and its full of mold and all wet under the cover, whats the best way to prevent this? My old boats never suffered from this, cant understand why, they were smaller boats with outboards, this one is a four winns horizon 4.3 omc. I could put a dehumidifier in it but that would drink electric, does anyone know of a fix?