Originally Posted by Seevee
Can you comment more on your dehumidifier? Kind and model no? And how hot does it get?
Sounds like a good idea.
I am quite happy with the result. This boat was built for the east coast and had two AC units, a 11K and a 16K. In the PNW, there isn't a lot of need for the AC, so I removed the 16K unit and put this in its place. If you had the room you could retain all the AC and add this to it - that is what they are designed for in houses. I used the existing power feed for the AC (disconnected from the other controls) and the existing condensate drain.
It does raise the temperature slightly, though if a humid day it will actually feel cooler. It runs about 400 watts, all of that heat is dumped in the boat. However the duty cycle is low unless something is dumping moisture in - such as an open door, cooking, showering, wet clothes brought in from the rain - so the average draw and average heat contribution are somewhere around 100 watts typically.
If the humidity is down around 50% anyway on a warm day, I don't run it, but open the windows. On cooler or wetter days, any heat is generally welcome and the boat is much more comfortable, dry.
There are several brands - just Google "ducted dehumidifier". I picked this one
because I liked the specs and the build quality. They are around $1100, a lot more than a portable, but a lot more convenient to use once installed.
First picture shows dehumidifier and AC unit it replaced, second one shows (mostly) installed. They are about the same size, the DH is boxier. I installed a remote dehumidistat, and needed an 8" -> 7" duct adapter at most boat AC seems to use 7". Other than that very straight forward to install.