I don't know why we didn't. You would think that we would have long ago.
Living aboard and dealing with the problems of humidity, especially in the winter when the boat is sealed up should have pointed us at this solution sooner.
In a dock gathering discussion last week, we realized that most of the other boats were keeping dehumidifiers running in the winter.
But my memories were of the huge clanking monster of a dehumidifier that my parents ran in the basement of our childhood home. It was a heavy, file cabinet-sized unit that needed its own circuit - it drew 15 amps. Not exactly appropriate for a boat.
But now we have the world's products at our fingertips - I did a quick Internet search and found this one - it draws only 1.6 amps, is small enough to live in the aft head, and yet is capable of pulling 25 pints of water/day out of the atmosphere inside the boat. It even has provision for a continuous drain (which I haven't set up yet), that would go right into the shower sump it is sitting above. Oh yeah... and that is distilled water it is producing too - ideal for the batteries. Finally, condensing water produces heat, so it functions as a small space heater too (you can almost think of it as a tiny heat pump).
One of the dangers of living with problems is that they cease to be viewed as problems after living with them long enough. If it hadn't been for that casual dock conversation, we'd still be living with the humidity.