Greetings,
The trick is to lower the dew point.
Dew point - Wikipedia, the free encyclopedia
Either by raising the temperature with heaters etc. or "diluting" the moisture laden air by mixing with dryer air (fans). If the whole boat is humid, moving internal moist air about with fans will do little to clear fogging from windows. Crack a port or warm the air. Oh, and shut down your bong....