Glen, there are three proven way to build the system you are looking
for:

1. Install a full length stainless steel holding plate in an insulated
box, it can be used as a dry box or a wet box. See picture on front
page of my web site, this box's holding plate is connected to a
Danfoss BD2.5 compressor. The purpose of the plate in this cooler is
to act as a flywheel affect of energy when warm product is put in the
box.
2. The same insulated box can be cooled by a plain copper tube coil
attached to interior wall. When I did fish hold box designs I used
stainless tubing with tubing above and below the water.
3. Either one of the above concepts can be used with an existing large
refrigeration system by splitting the refrigerant flow.

I have system #1 in one of my boats and system #3 in the other.

Glen here is a concept using a Danfoss BD50 air cooled condensing
unit, and 50 ft. of ¼ inch tubing as an evaporator coil, A receiver
and expansion valve instead of a capillary tube.

This combination in a drink cooler with a 30 degree evaporator
temperature might deliver 790 btu. Per hour. ( Danfoss ASHRAE
Capacity chart with compressor running at 3500 rpm ). I would also
install a manual speed selector switch to adjust compressor speed for
current box demand.

From the author of books on boat refrigeration
http://www.kollmann-marine.com


Glenn Ashmore wrote in message news:07aTc.27910$Jo1.1742@lakeread01...
On our recent BVI cruise I started thinking about cockpit drink coolers.
The beneteau 505 has a very poorly insulated cooler in the cockpit
table that is a total waste of ice. RUTU, being derived from a modern
high performance design, has a very wide fairly shallow cockpit. It
will need foot rests to keep braced in the seats on a heel. I am
thinking about building a perminent heavily insulated box down the
center. It could also be used as a seat at anchor when the table is
folded up and the cushion would serve as additional insulation.

Now the question is how to keep it cold. I am thinking that a small
evaporator type system would work. Drinks cool fastest in water so
stocking originally with drinks and ice would provide the water. Once
the ice melts the evaporator would maintain the temperature and the
water would serve as a heat sink.

What I am worried about is that the aluminum evaporator would corrode
rather quickly constantly submerged in water. I am wondering if several
loops of copper tube might make a better evaporator.