"Larry" wrote in message
...
"Roger Long" wrote in
:

One of the damndest things I ever saw in a museum was something called
a Shaker refrigerator. It was an insulated box with a slot in the
side. There were two metal balls, about the size of small soccer balls
made of what looked like zinc or galvanized steel with a pipe soldered
on connecting them at the top and separating the balls by about 18".
You put one of the balls in the fire and heated it up to nearly red
hot. After it cooled, you put that ball in the refirgerator and ice
formed on it for about 12 hours. Then, you took it out and put the
other ball in the fire, cooled it, and put it back in the box the
other way round.

I think the balls were filled with ammonia. I suppose you could make
one of these work by putting the ball in the BBQ grill over the
transom.

Clever people those Shakers. Shows how much mental energy is left
over when you aren't spending 18 hours a day trying to get into your
neighbor's wife

--
Roger Long





That's the Absorption Cycle. Go look how any RV refridgerator operates.
The freezing comes because Ammonia just LOVES water. When Ammonia
combines with water heat is absorbed. The gas burner (or electric
heater when the RV is plugged into the park) merely boils off the water
and ammonia to separate them so the cycle can repeat...simply by gravity
flow. There's no pump needed....just heat. I know someone with a
kerosene refridgerator that runs on a kerosene wick lamp. The lamp
heats the boiler, instead of a propane flame. It was a really old
fridge, probably of historic value.

UNfortunately, for sailors, this fridge needs to be LEVEL to operate
properly because it is a gravity-flow device. If the RV is tilted just
a couple of degrees off level...the fridge just stops. They also
sometimes become vapor locked by water being in the wrong place. The
solution to that is also quite simple. Remove the fridge from the
camper, turn it upside down and leave it that way overnight. Flip it
back over and reinstall and it works fine, again. I think this kind of
fridge would be fine if gimbal mounted. They cool just fine in a MOVING
motorhome roaring down the interstate using its 12V heating coil to save
propane. I had a big Dometic refridgerator-freezer in my last motorhome
that would do any sailboat proud. It ran off of 115VAC, 12VDC or
propane, your choice. It would run just as well off an alcohol flame to
keep the fumes out of the bilge. The gimbal mount would level it so it
would work while the boat was heeled over by the sails.


Mine works great on my catamaran, a 20Lb bottle lasts about 4 weeks.

Cheers.