Look up Nicro Solar Vent. It uses a NiCad C-cell (I would guess you could replace that with an NIMH c-cell) battery. During most days, even cloudy ones, the built-in solar panel keeps the battery charged enough to run all night. Mine has been running for months and I have changed the battery only once or twice in probably 10 years of running. Sometimes in the winter, I turn it off because I use those mildew prevention gas bags and I believe the exhaust fan exhausts that gas.
They don't pull a lot of air but enough to eliminate condensation or at least reduce it significantly.
In my Bowmar hatch - and probably the same hatch in many or most Marinettes, you cut a 4 inch hole (hole saw) in the lexan/plexi and drop the unit in place. No screws..just a bead of silicone. I would not use 5200 because it's "permanent (though it CAN be dissolved). I forget which silicone type I used. But it held for a number of years, then I scraped and replaced it.
These things are overpriced so shop a bit. I think I got best pricing at Defender. It will be different today. I say overpriced..but they seem to work.
(btw, of course there will be more condensation when you have the interior heat on -- warm surface aqgainst cold and all that kind of physics stuff)
Joel Albert, Potomac MD
"Charlie B" - 1988 32' FBS
Twin 318's/FWC/16x15 nibral props
docked Deale, MD
