HYPERVENT IS THE ANSWER!!!!! I tried everything mentioned on this forum, and nothing worked. I ordered enough HyperVent for 1 bunk, as a test, and have had NO problem since. I will be ordering enough for the other 2 bunks soon.
Call 360-657-5503 and talk to Rex. He can answer any question you have, and give you installation tips. Check out HyperVent Marine - Putting An End To Condensation
If you are still unsure about it, I have enough left over to send you a small sample, if you want. I told Rex if this worked, I'd do free PR for them forever.
And I will.