We’re on the Texas Gulf Coast so high humidity is just a fact of life. You have to use something to dehumidify or the interior of the boat will have mildew and a bad musty smell. When we first got the boat, we ran the AC in “dehumidify mode”. That worked well, but it put lots of hours on the AC unit.
When I looked at the cost of an AC unit compared to a portable dehumidifier, it makes more sense to use a portable dehumidifier. We leave a dehumidifier running 100% of the time when we aren’t on the boat with the setting at 35% Relative Humidity. It does make it hot inside the boat, but it eliminates mildew and the musty smell.
The dehumidifier that we have had the best luck with is the Frigidaire FFAD7033R1, 70 Pint/day unit. We’ve tried GE, LG, and others, but the Frigidaire works better (knocks out more water) and they seem to last longer. You can get the same one we have for $260 at Amazon with Amazon Prime delivery. I’ve put a link to it below.
https://amazon.com/gp/product/B00UWP...?ie=UTF8&psc=1
However, if I were buying a dehumidifier today, I would spend $16 more and get the newer version of the Frigidaire that has a built in condensate pump. With the one I have now, I have to sit the unit up on the galley counter so it can drain through a water hose into the galley sink. It’s a fairly big unit to have sitting on the counter and it’s heavy to lift up and down. With the unit with the built in condensate pump, you can locate it most anywhere and you just run ¼ “ polyethylene tubing to wherever you want the condensate to go. You can run the condensate drain to the galley sink, the head sink, a cockpit drain, or any other drain. I wouldn’t suggest running it to the bilge because the dehumidifier knocks out almost 9 gallons of water per day. If the bilge pump stopped working, you could conceivably flood the boat with condensate over time. Having the built-in condensate pump just makes the dehumidifier easier to deal with. I’ve put a link to that unit below.
https://amazon.com/dp/B06Y1M6XPT?psc...02_03_t_ttl_lh
You can get this unit in 2 days from Amazon.