In article fce2f2ae-ac61-410b-8d98-1f91d8dfe8a4
@u24g2000prn.googlegroups.com, says...

As I want to do more sailing in the low latitudes but do not like to
sleep in sweat, I have been looking into ways to cool my boat with
semi-passive means. One thing most boats have is lots of sunlight and
a lot of water for cooling. So, we have a source of heat and a way to
get rid of heat, you should be able to use that to cool air. Turns
out there is a way to do this, adsorption cooling.
Such a system uses a material like Zeolite that quickly adsorbs water
from a reservoir thus reducing pressure and cooling. This can be used
to cool air. The zeolite must then be regenerated to remove the water
and this is done by heating it and then allowing it to cool.
So, we use a solar concentrator to regenerate the zeolite and a 12 V
pump and a 12 V fan. The Zeolite is cooled by pumping seawater thru
coils imbedded in it. Not driving a compressor makes this easy to do
with 12V and very efficient.
Thus one could operate an AC unit from a solar panel and a solar
concentrator. No, it would not reach meat locker temps but compared
to 100 degrees and 100% humidity, 80 degrees and 80% humidity is
paradise. Thoughts?

I would take two hoses and hang them 10 feet or more into cooler water
and pump fresh sea water through a radiator like in an AC. Then set up a
fan to direct cabin air through the radiator (like an AC) which would
suck heat from the cabin air and pump it back into the ocean (this would
be an open system, fresh water in, heated water out... and probably
expel cooler air back into the cabin. The amount of cooling would depend
on the water temps at the level you are taking it from. Theoretically is
shouldn't make a lot of difference how deep you go in relation to the
pump, to a reasonable extent, either... Right??