Refrigeration for hot climes

[Becky]

We are in the process of sorting out our new (to us, anyway) boat with a view to Caribbean cruising in the future, and would benefit from advice on fridges. We have fridge which has a fan-cooled condenser. This I suspect will be heavy on electricity, so a water-cooled one would seem to be better. Where would we obtain such a thing. And who supplies and fits them? Also I would very much like a freezer. There is room for a small one as a conversion of one of the two cold boxes. Any suggestions on where and who to contact?

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[snowleopard]

there are several firms producing refrigeration for boats. one example is Isotherm (swedish). Penguin marine on hayling can also help.

for the caribbean it is essential to have water cooling. i would suggest 'keel cooling' i.e. a heat exchanger on the outside of the hull as you could have problems with an intake pump sucking air (the bane of our lives).

for a raggie you would be best off having a eutectic (holding) plate which can be charged up while motoring and will keep things cold for 12 hour or so when sailing without any more current draw.

before deciding what system to get, check your insulation. freezers need 4ins insulation at the sides, 6ins at the base and 2ins at top. fridges about half that. you can make a fridge/freezer by putting the evaporator in one half of the box and dividing off the rest with a bit of perspex.

to be able to keep frozen food in the tropics requires very serious kit and professional installation but the setup described above will keep ice cubes frozen for your rum punch!

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[Sunnyseeker]

We sailed for a year with an isotherm fan cooled holding plate frigde, it actually worked fine not drawing too much current, we actually had too much juice as we used a towed generator when sailing (aerogen aquagen 100) and hung it up in the wind when we parked. the only thing against the fan is the noise of the fan, it ads a bit of heat downstairs but its going to be warm any how, and being british we still had to run the stove to have cups of tea...
Dutch friends had a water cooled Isotherm, needed a bit of plumbing taking the sea water from the engine intake on a T piece but it worked silently. It would also depend on where the fridge was and where the water was....ours was a long way from any sea intakes so would have needed quite a bit of sea water plumbing..
With the towed generator we used the fridge to regulate the electric, if we sialed faster we turned the fridge up...
Have fun more important is sorting the ventilation for you downstairs, fans and good scoops etc

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[jerryat]

Hi Becky,

I don't think a water cooled unit is essential. Like Sunnyseeker we have sailed in hot areas (Med and caribbean) over a 7 year period with a basic fan cooled Isotherm with standard condenser plate. No problems at all and no problems with excessive current use. I suspect the reason is that we took considerable pains over insulating the 'coolbox', by adding special insulation to the INSIDE and covering this with Formica sealed at the junctions with silicon.

We used the insulation (approx 30mm thick) produced for the 'fridge installations in the supermarkets, which has foil on both faces, white one side and silver the other. Closed cell and very effective.

This, added to the existing insulation, reduced heat loss to a minimum.

Out of interest, and similar to Sunnyseeker, we used 2 x 55 watt solar panels, a towed Aerogen 6 and a Rutland 913 windgen. On long passages we virtually never ran the engine, and when we did, the Adverc produced heaps of juicy amps that soon topped up the batteries.

No doubt water cooled versions can be very efficient but a simple system can also be equally good IMHO and is certainly much cheaper!

Final thought. Two friends of ours had the Isotherm Version that has a single thru hull 'flow and return' type system. BOTH experienced awful problems of fouling, poor circulation and subsequent cooling problems with their refrigerators. It might have been co-cidence, but then it might not.

Hope this helps

Good sailing!

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[roly_voya]

Not been to hot climes so have no direct experience but I have looked at fridge instalations and the most common problem seams to be air flow to the heat exchanger, I suspect this is why some units work well and others don't. So as well as looking at the insulation it might be worth considering ducting cool air from the bilge and venting the warmed air to the deck, maybe even adding a blower.

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[jerryat]

Hi Roly Voya!

Yep, that's a very good point I forgot to mention in my post! I sited my compressor in the cockpit locker, where (most of the time!) there was plenty of air to circulate. In addition, and whilst not on passage, we made it a point to block the locker lid slightly open, to allow even better circulation. We had considered putting the comp. below, but even with the large lockers on my Fulmar, we felt them too confined, in addition to which we had no desire to hear the fan cutting in and out. You have to listen extremely carefully on a silent night to hear anything in the saloon.

Good sailing!



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[SimonJ]

Suggest Becky you read Nigel Calder's treatise on refrigeration, etc!
Good insulation essential.
I think water cooling essential. Keep it simple, there are always lots of boats out there waiting for a 'fridge expert to arrive & repair their unit. Isotherm SP systems have worked well for me. Deepfreezes seem to be a nightmare. You usually cannot leave your boat for long as in most installations unit has to be powered by the engine which then has to be run about twice a day. difficult then to go on long explorations ashore.
Worry about ALL your electrical power usage and make sure you have the means of putting in what you take out. A mix of wind gen, towed gen and solar panels to back up the engine driven alternator is desirable. Fridges use a lot of electricity! So do lights etc in Caribbean where days are short and nights long.
Remember you will be anchored 90% of the time and not often on passage when a towed gen can be used - so not necessarily a good investment.
SimonJ

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[Sunnyseeker]

Similar to others comments we had friends with problems on their water cooled units, the pipes are small and blocked up with growth/barnacles...didn't come across any problems with air cooled units but you do need to duct the air supply in, and duct the exit warm air out.
The towed gen I feel is esential, I would never sail without one! we didn't have to use our engine at all for electric, we had an Aquagen 100, which converts to a wind gen when anchored. It was also silent in operation even at 25-30 knots wind...mounted over the boom.
When sailing your using more electric with nav lights, electronics, and then the towed unit chucks out loads of amps...8-10 all the time, at anchor you use less and the windy was fine.
I dont have shares in Auquagen but might think about it

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