11 Oct Refrigeration: Extra Insulation
Adding extra insulation to your galley refrigerator can dramatically lessen the power needed. Below are 4 simple and inexpensive ways to add extra insulation without rebuilding your boat’s refrigerator.
Aboard Que Tal, Dave and I cruised the Sea of Cortez and as far south as El Salvador, where summer temperatures were often over 100 for days on end. On top of the heat, our refrigerator was next to the engine compartment and next to the companionway with the sun beating down on the (dark) teak surround. We quickly figured out how to add extra insulation without totally rebuilding the refrigeration box (which would have been a very messy and expensive option).
1. Counter Mat. I got a foam exercise mat, cut it to the exact dimensions of the counter top (less 1/2″ all around) and had a canvas shop put a white scrub-able vinyl cover over it (the seams made up that 1/2″ so it was now the exact size of the counter top) and laid it on the counter over the fridge.
Why the vinyl cover? Since this was my main food prep counter, the vinyl made it easy to keep clean, as the mat I got had a porous surface. Newer mats, such as the one recommended here, have a washable surface and may not need a cover depending on how much food prep you do on this area. For me, the other reason was that the only suitable mat I could find was black. One of my problems was that the top of the refrigerator was in full sunlight, so I wanted a white surface that wouldn’t absorb heat, and the vinyl cover gave me that.
To get into the fridge, I just flipped the cover back.
I recommend a 3/8″ thick mat for two reasons — while a thicker one will have more insulating power, it is also more difficult to cut to size, and will be stiffer and hard to keep “flipped back” when you want to get into the refrigerator. You need one that is flat on both the top and bottom — on top, so that you can use it as a counter area and on the bottom so that air doesn’t get between the mat and the top of the refrigerator.
My recommendation, from Amazon.com:
2. Auto Windshield Reflectors. We got two auto windshield reflectors and duct-taped one around the outside of the refrigerator with the silver side out to keep that teak enclosure from heating up. It was easy to cut it to the exact size needed and while it didn’t look pretty, it considerably reduced the drain on our batteries.
The other reflector we cut to size and laid it inside the fridge on top of all the food. We had two access lids into the refrigerator, side by side, and used one far more frequently than the other. Eventually we cut the reflector down again and just used it over the side with the chill plate, which we got into much less frequently — we had discovered that having an extra layer of insulation on the side we used frequently just made it too hard to get to the drinks.
The reflector doesn’t need to be anything special, unless you want a particular color or design to improve the appearance of the one that’s visible (Wal-mart, Target and auto parts stores often have ones with sports logos, Disney characters and so on — at a price).
3. Foam Insulation Sheets. Friends on a boat in the US bought some rigid foam insulation (large blue and pink sheets available at home improvement stores) and cut pieces to fit in their refrigerator and inside the lid, then used silicone to hold them in place, as in the photo at the top of this article. We weren’t able to find the rigid foam where we were, but I know several people who have done this and all said that it made a significant improvement, didn’t take a lot of space out of the refrigerator, and was easy to do, taking less than an hour. Don’t put it on the bottom of the refrigerator or in the bottom 4″ of the sides, as meltwater from defrosting will saturate the foam.
4. Hanging Sun Shield. Almost every boat in the Sea of Cortez for the summer hung something — an auto windshield reflector, a piece of white Sunbrella, whatever — on the outside of the hull over the refrigerator area. Dark-hulled boats said this made a HUGE difference to them; we noticed a small improvement (we had a very high gloss new white paint job).We also tried putting some insulation inside the engine compartment on the wall common to the refrigerator. Unfortunately, there was very little room for insulation and it didn’t make much of a difference.
UPDATE: After I wrote this article, other cruisers told me about using Reflectix to easily add additional insulation. Read about it here.
If you want to delve deeper into boat refrigeration or are considering replacing yours, I heartily recommend Nigel Calder’s book on the subject:
Have you tried any other ways of adding extra insulation to your boat refrigerator without re-building it? Add your experiences in the comments below — both of things that worked and, equally important, things that didn’t.