Marine Air Conditioners cost around $1,300 and that is just too much. :(

Marine units differ from home units in the way they remove the heat. Home units blow air over a condenser coil and marine unit use a water cooled condenser to remove the heat.

I have been converting (NEW) windows units by replacing the air cooled condenser with a water cooled condenser for some years now and they always work great.
After building many of these units for friends I decided to sell a few as time to build them permits.
In order to use these units you need to run a water hose connection from the dock to the unit. You may use an on-board water pump, as do most marine units. You also need a hose connection to discharge the water over-board. I like use heavy-duty, reinforced hoses as you sure don’t want a hose leak to fill you boat with water!

I prefer to install the units where the condensate can drain into the bilge and I like use quick dis-connects on the hose ends.