What is the best insulation?

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Bilgerat

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Hello,
I'm currently refurbishing a 25 year old Nordica 20 and would like to build in a permanent ice box. This past season, we have been just using a picnic cooler, but find this most unsatisfactory for longer cruises. Obviously, with just a 20 ft. boat, space is at a premium where every inch counts so using 3 inches all round would be out of the question. Therefore, I would like to get opinions on the best insulation to use for the new icebox and also any ideas on construction..
I live on Cape Breton Island on Canada's east coast and as our cruising tends to be in remote areas where unlike the UK or Europe where there is a pub within a stones throw from every town dock. Iit is imperative that I'm able to look forward to having a cool brew at the end of a long days slog to windward.
Cheers,

Fun is inversely proportional to length ! !



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How big a space can you make available, and how long are your cruises?

There's an easier way around this. Put in the biggest cooler box you can fit. Then fill it with frozen beer cans from your home freezer. I can keep beers cold for 4 days with this technique.
If you need to keep food cold as well, and beers available to drink, juggle available space with frozen cans.

Just take them out well before you need to drink them on the first day or two., or you'll have alcoholic slush puppies

Don't try to freeze non alcoholic cans, they will explode in the freezer

<hr width=100% size=1> I asked an economist for her phone number....and she gave me an estimate
 
Great advice this, even if you have a fridge. I have a compressor fridge but use the frozen beer technique. Keeps the electricity requirement well down for anything up to a week. And then you drink the beer!

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From the figures I can find, low density closed cell rigid PU foam gives the best insulation you can find. The thermal conductivity is around 0.02W/m^2.K. Mineral fibre (like Rockwool) is 0.03W/m^2.K.

The density you want to be looking at is 30kg/m^3 tops. More than 45 kg/m^3, and you'd be better off using rockwool. The lower the density the better, as the thing that really does the insulation is the air trapped in the foam cells - the PU has a much higher conductivity than trapped air.

Regards

Richard.


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I made my own fridge two years ago and am very pleased with the result but a year later we moved and had to have some renovation to the new house involving insultation. We needed to dry line the ceiling of the single storey extension from inside and in order to reduce the ceiling height lost through adding the insultation, the builder fitted an insulation panel called 'Selatex' (phonetic spelling). It was 1" thick and had an aluminium face, very dense and therefore a little heavier than ususal insulation. It's performance is very very good as an insulator and I wished I had known about it before I made the fridge. Don't know if it will have the same trade name where you are but I think the key is to ask your builders merchant for high spec insulation and see what they have.

I had a fibreglass shell made for the area to be cooled with gel coat on the inside for cleanability and fitted a compressor and evaporator plate that came as a kit. the gas is in the compressor and spreads to the rest of the system as you couple it up. this was a Waeco system and very good it is too.

Lid is quite important. I have a top loader and thus cold air does not fall out. I don't have too good a fit on the two lids and I will have to redo these sometime. I have no drain in the box as the bottom is below the waterline so have to accept cleaning it out every so often but this is not too much of a trial.

Well worth doing. I tend to only have it on while motoring or hooked up to shore power.

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Have you thought about a proper portable fridge? About the same size as a picnic cooler but has a proper compressor, so the running load is very low(compared to a picnic cooler)typically ½amp/hr as against 4amp for the cooler. Mine is a Waeco and they do 3 or 4 different sizes. From £250 though....
Again use frozen beer cans or icepacks to keep it cool to begin with. The Waeco, I plug into the cigarette lighter in the car whilst travelling to the boat, and the just plug into the boat 12v supply.


<hr width=100% size=1>dickh
I'd rather be sailing... :-) /forums/images/icons/smile.gif
 
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