Condensation occurs when moist(perspiration-laden) air reaches a cold surface - on bunks, normally a plywood base.
I have found that Andy's & John's solutions work well enough but an effective(and cost-free) solution is to proceed as follows;
Before replacing the mattress covers after...
I fitted a single,low-cost speaker to my Hussun VHF last summer and it works fairly well(£9.98 from Cruisermart). One drawback is that plugging in the cockpit speaker disconnects the Hussun`s internal speaker. The July issue of PBO has a good article on this dilemma and how to overcome it; also...
John, If it is any consolation to you, I own a Westerly Fulmar,Bukh 24 engine, with the same "problem". I raised a similar query to your own on the old Forum. The most interesting reply I got was from the...