The icebox lid. Not a lot of insulation there!

(UPDATE on this article: I replaced my sailboat refrigeration system with the Technautics CoolBlue DC system – you can read about it here.)

I’m thoroughly entertained by some of the questions that people ask me about living on a sailboat.

It’s not their fault; they just don’t know anyone who lives on a boat and they have no idea what it’s like.

Sometimes I have a feeling that people imagine me in a little dinghy, covered by a canvas cloth for protection from the elements, with a cooler and camp stove for cooking.

The truth is, it’s closer to a one-bedroom apartment than most realize. Just a one-bedroom apartment that requires a lot of maintenance, gets freakin’ cold in the winter, rocks (sometimes violently) with the wind and water, and will go anywhere in the world that I want to go (and you thought it was doom & gloom until I added that last part!).

I don’t cook with a camp stove; I have a two-burner propane stove and oven/broiler that I’ve used to make some tasty meals. And I have a refrigerator as well…it’s just that refrigeration seems to be an afterthought for most boat builders, and my boat was no exception.

While the refrigerator is easy to access, that’s about its only advantage.

The problem with boat refrigeration is heat transfer. The walls of my icebox are fairly robust – a couple inches of polyurethane foam between fiberglass moldings – but the lid is nothing more than a thin piece of wood with a handle. I can hold my hand against the outside wall of the refrigerator and feel no cold, an indicator that not much heat is entering from the walls. But when I put my hand on the lid, it feels frozen – a sure indicator that heat is entering from the lid.

I currently have to run my refrigerator compressor about once a day to keep the beer cold and the food at a safe temperature.

So backing up, how does the refrigerator work? In short, the compressor, using a condenser (heat exchanger) with seawater, pumps refrigerant through a holding plate in the icebox and cools it.   This holding plate is like a giant block of ice; after cooling, it will slowly absorb heat from the icebox.

Better insulation means not having to run the compressor as much, and with a compressor driven by the engine, this means not having to run my engine as much. Soon I’ll be adding an electrical motor to the compressor, which means I won’t have to run the engine at all to cool the icebox.

Right, so where am I going with all of this…the lid. This was an easy, cheap fix. I made an outline of the access hatch with cardboard, and constructed a two-inch deep mold. Inside this mold I sprayed polyurethane foam (one of the best insulators – not styrofoam).

After letting the foam cure overnight, I sawed off the top to make it flush (it expands as it dries). Then I dropped the lid on top of this new layer of insulation, secured the two together, and taped the hell out of it until it made for a nice, snug fit in the hatch. I could have glassed it over (with fiberglass) but I didn’t want anything too permanent in case I needed to change it or improve it later on.

The results?  I now only have to run the compressor about 30%-50% of what I was before (depending on outside air temperature) to maintain the same temperatures inside.  Over time, the energy savings are incredible – less fuel and less electricity for an equal, or greater amount of cold beer!

The icebox lid now with 2″ of polyurethane foam added for insulation!

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