I priced a drop in hatch
A/C unit (for use at the dock) at West Marine. If my memory serves me it was around $1100 for a 5000-6000 BTU unit. It looked to me like a cheap
window unit in a plastic shell which fit through the forward hatch
I built a 3/8" plywood housing that drops in the hatch and is custom fitted to my hatch. I put it together with stainless screws and marine epoxy
. I gave it a sealer coat of epoxy
and three coats of marine enamel. I got a GE window unit at WalMart for $90. Set the housing in the hatch, push in the window unit. I bought a large outboard motor
cover at Wal Mart, split it on one side, and attached it to the housing with SS screws and grommets. The cinch cord tightens the cover around the open hatch and assures a rain tight seal.
The unit work like a charm. You will need to build baffles for cool air and return air. The controls are accessible from the inside of the cabin
Total cost was about $175. The filters are cheap
and readily available. If the unit needs service
, it is about as common a unit as is found. If it bites the dust, a new GE window unit is available almost anywhere, including many Carribean islands.