I have never heard of this conversion, but there are portable units sold that reject their heat to water instead of to the air. The ones commonly used in laboratories use tap water, and I don't know if it is possible to use salt. The portable unit that used to be sold had reliability problems and you don't see them anymore. I often thought that one of these would be good for a boat, but I ended up getting a 'portable' unit that blows the hot air out the window through a 5" hose, because it was cheaper. The portable units are nice in that they can be removed from the boat when going on trips away from dock power.

The one I got is made by Sharp, a CV-10NH model rated at 10,000 btus. On low speed, it is as quiet as a fan.

It seldom sees low speed, however. It will not cool the boat at all on a typical Florida summer day. During the day if I am on board I run a large circular fan set in the cockpit that blows through the whole boat. Nothing special about the fan, it is a unit usually used at construction sites or in shops.

At night when it is still pretty hot out, the Sharp will cool into the high seventies, eighty at most. Most of its capacity is used up in taking water out of the air. This is comfortable for me, since I like a little heat but prefer to have it dry.

When I am not aboard it works as a dehumidifier.

I hooked up the drain to get rid of the condensate, because the directions said that it would be a little more efficient that way.

I imagine that this unit would be enough in many parts of the country. If I ever live on the boat full-time, I will install a marine unit with 1800 or 20000 btus.