Backup cooling for icebox

JumbleDuck

JumbleDuck

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I have a smallish boat with a smallish icebox which works very well, melting its way through 2 kg of ice on an average day - 3 kg in a heatwave, 1 kg in the off-season.

I have been thinking about adding some refrigeration. Not a full fridge because I have neither room nor power for one, but something which could add some coolth to the icebox when the engine is running and there is power to spare.

Since the latent heat of ice is 333 kJ/kg, 2kg/day is an average of 4W. That probably means a peak of 20W at midday, so if I could shift 40W out I'd be winning. As far as I can see, I have two options: a small compressor system with evaporator plate in the coolbox or a Peltier system in the. The compressor system would be much more efficient (Peltier units in the 50W range seem to be about 80% efficient), but for the small powers and usage patterns I envisage that wouldn't matter.

So ... has anyone added a bit of cooling to a cool box without going the whole fridge hog? How did you do it and does it work? Any other advice very welcome.
 
The cheapest easiest simplest most guaranteed to work solution is to find space in your boat & your heart for a compressor coolbox & use the built in one to store biscuits & porridge. I have a Waeco CF18 & it uses 6 Watts on average over a Scottish summer. I switch it on in May & off in September. It's only wee at 18 litres but I can get lot of scram in there by unwrapping & bagging bulky stuff.

There are much cheaper ones available now.
 
I arrive at the boat with everything frozen and thaw it out if we need it on day one (a bucket of salt water will defrost stuff in no time). If only I could get a few buckets of ice from the fish market.
 
AngusMcDoon said:
The cheapest easiest simplest most guaranteed to work solution is to find space in your boat & your heart for a compressor coolbox & use the built in one to store biscuits & porridge. I have a Waeco CF18 & it uses 6 Watts on average over a Scottish summer. I switch it on in May & off in September. It's only wee at 18 litres but I can get lot of scram in there by unwrapping & bagging bulky stuff.
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Looks good, but I simply cannot see anyway of fitting it in to anywhere except the cockpit locker which is full of warps, fenders and so on. it's also quite a bit smaller than the ice box. However, I'll certainly think about it - thanks.

Sandy said:
I arrive at the boat with everything frozen and thaw it out if we need it on day one (a bucket of salt water will defrost stuff in no time). If only I could get a few buckets of ice from the fish market.
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We had real problems getting ice in Mallaig a few years back until I discovered that Spar gets three bags delivered at 9pm. It was galling to be in sight of an ice company ... minimum order 1 tonne.
 
I live in a hot climate with lots of pleasure boats. The best practical food/drink cooling arrangement if you can't go top full compressor fridge arrangement is the ice box.
The insulation and lid sealing is important. Large block of ice will keep for some days. Of course the bigger the cool box so bigger the block of ice the better. Frozen water in milk bottles is good. One trick which may help you is to put the ice in further insulation. Our super markets sell an insulated bag for taking home frozen stuff. This could be ideal for insulating ice. Of course by insulating the ice you won't get so much cold in the box but it will last longer.
In travels in car we used an Engel small freezer running off car alternator battery during the day. Seemed to remain frozen over night. We would take out frozen food for thawing and put in to a cooler box. (known in Oz as an Esky) which kept box cool all day while defrosting frozen food.
So my suggestions to OP. Try to increase box size if not improve insulation. Try more ice in the box. Or buy a Waeco 18l freeezer.
Do not consider peltier cooling devices. They are just a waste of 12v current, heat into the box and money. ol'will
 
Compressor fridge kit to upgrade your current ice box. Keel-cooled if you can, as they're significantly more efficient.

VjAtOnl.jpg
 
William_H said:
So my suggestions to OP. Try to increase box size if not improve insulation. Try more ice in the box. Or buy a Waeco 18l freeezer.
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The box is built in to the joinery so beautifully that both extending it and adding insulation (which I woul dlike to do) are out o fthe question. A separate freezer for producing ice woul dbe tempting.

Do not consider peltier cooling devices. They are just a waste of 12v current, heat into the box and money. ol'will
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I'd only run one when I had amps to spare.
 
Agree with AMcD. On our first boat we had the same as JD, a cool box but also used a portable Peltier one. Fine until we got our current boat with a compressor fridge. It was like moving from the dark ages. Worth the money and if needed, solar / wind to keep it going. Now we switch the fridge on when we arrive on the boat and off when we leave.

AngusMcDoon said:
...It's only wee at 18 litres but I can get lot of scram in there by unwrapping & bagging bulky stuff...
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WHAT? Food in the beer box? Hang your head in shame! ???
 
ctva said:
Agree with AMcD. On our first boat we had the same as JD, a cool box but also used a portable Peltier one. Fine until we got our current boat with a compressor fridge. It was like moving from the dark ages. Worth the money and if needed, solar / wind to keep it going. Now we switch the fridge on when we arrive on the boat and off when we leave.
Click to expand...
I have two nice new Sunbeam Systems 54W solar panels, which peak at just over 5A into the batteries. That's more than enough for our needs (all LED lights, instruments, laptop etc) but really does not leave enough over for significant refrigeration.
 
AngusMcDoon said:
The cheapest easiest simplest most guaranteed to work solution is to find space in your boat & your heart for a compressor coolbox & use the built in one to store biscuits & porridge. I have a Waeco CF18 & it uses 6 Watts on average over a Scottish summer. I switch it on in May & off in September. It's only wee at 18 litres but I can get lot of scram in there by unwrapping & bagging bulky stuff.

There are much cheaper ones available now.
Click to expand...
I have the 25l Waeco, and it will provide ice which you can transfer into a cold box. Can you increase the insulation within the coolbox, as you would have additional storage within the Waeco, if you were to go down that route.
 
We have a couple of Halfords type Peltier cool boxes that we use in the car and had one built into a boat we bought many years ago. Certainly not as good as a compressor fridge but quite adequate while the engine is running.
 
KompetentKrew said:
Compressor fridge kit to upgrade your current ice box. Keel-cooled if you can, as they're significantly more efficient.

VjAtOnl.jpg
Click to expand...
This is sales blurb. No mention of condensing temperature, cabin temperature or sea temperature. Having had both systems Installed on our boats I do not believe these graphs.
I think the difference in power consumption is not as significant as these graphs suggest
 
25 to 30% reduction of input power very possible with reduced condensing temp due to keel cooling. Easy estimate in refrigeration industry is 3% power for each 1 degree change
 
ctva said:
Agree with AMcD. On our first boat we had the same as JD, a cool box but also used a portable Peltier one. Fine until we got our current boat with a compressor fridge. It was like moving from the dark ages. Worth the money and if needed, solar / wind to keep it going. Now we switch the fridge on when we arrive on the boat and off when we leave.



WHAT? Food in the beer box? Hang your head in shame! ???
Click to expand...
IMHO, beer tastes better when it hasn't had all the flavour frozen out of it, (except mass market lagers such as Bud, Millers et al, which seem to be made for people who don't actually like beer :) )
 
With heat dissipation into the surrounding water even Peltier technology can come down to acceptable power consumption. I have such a unit in what was originally an ice box. These systems were manufactutred for a few years around the milennium. Great products, but unfortunately did not catch on.
 
we have a 50 litre Polarbox compression fridge freezer it is excellent bought a larger 130 litre one last year but it was to big to go through the spare bedroom door so it was difficult to site sold it bought the 50 which is a good size and fits in a number of places it’s 240 or 12 volt
 
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