Boatworks

Reefer Madness

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During our first summer cruising full time aboard Que Tal, our Tayana 37, my husband, Dave, and I were convinced we needed a new cold box in the galley. The fridge compressor ran all the time, the lettuce always froze, and I could never find what I wanted. We even went so far as to get a quote for having a new cold box installed. But after talking with more experienced cruisers, though, we decided to put the new box on hold and try some of their suggestions. A few simple changes made all the difference in the world.

Think inside the box
If you have a big top-loading cold box like ours, you need to do some serious organizing. Your goal should be to ensure that you don’t have to keep the box open too long when you need something, that everything is kept at its proper temperature, and that the space is fully utilized.
First determine your priorities. Do you need ice in your drinks, or will “cold drinks” suffice? If your freezer is tiny, you may have to choose between ice and freezing meat. If you want plenty of cold drinks, you may have to eat more canned fruit, vegetables and meat. If fresh produce is important to you, there will be less room for other things.
Then, think about what needs to go where. The coldest part of the box is at the bottom, right under the cold plate, a good place for meat. The bottom is also good for drinks, not only to keep them cold, but to prevent them from falling onto fragile items. The warmest area is at the top, away from the cold plate, making it perfect for things like lettuce.
If you want to fine-tune which parts of the box are coldest, it’s easy to wall off sections. Rigid foam insulation works best, but a double layer of corrugated cardboard will do. Cut the material to size to make a wall between the “cold” and “cool” sections of your box and then duct tape it in place. The side with the cold plate will be quite cold, possibly freezing, and the other side much less so. You can adjust the relative temperatures by making holes in the divider so more cold air passes to the cool side. Don’t cut too many holes all at once, as it takes about a day for the relative temperature difference to establish itself.



Organize your fridge's contents in containers so as to use the space efficiently. You can add a wall of foam to create different temperature zones.

Next you should group items together in containers to ensure that foods stay in their proper temperature areas, that fragile foods are protected, and that you’ll be able to find things quickly. Covered containers work well for things like lettuce and tomatoes that you don’t want squished. Otherwise, I like containers with open tops for easy access, solid bottoms in case anything leaks, and ventilation holes in the sides. It may take some trial and error to come up with the best container sizes and to figure out how they should be placed in your box, but in the long run containers pay huge dividends. Your food will stay fresh longer and you’ll find what you need much faster, which will save you both frustration and electrical power.  

Improving Efficiency
We did three things–each costing
nothing but a bit of time–that significantly improved our refrigerator’s
operating efficiency and reduced its power consumption.

Simply plugging the drain in our cold box reduced the fridge cycling time by 20%

Stop the Drain
If your refrigerator has a drain to the bilge, make sure this drain has a stopper or a trap in it. Otherwise, since hot air rises and cold air sinks, all that lovely cold air from your fridge will go straight into the bilge instead of chilling your food. The drain in the bottom of our cold box turned out to be our single biggest problem. Five minutes of work and a wine cork trimmed to size cut the time that our refrigerator ran by about 20 percent. Just make sure you can remove the stopper when you defrost and want to drain melt water.

Defrost Often
As ice (as opposed to frost) builds up on the cold plate or evaporator box, it actually insulates it, preventing it from chilling the contents of your cold box. Defrost whenever there is a ¼-inch buildup. Aboard Que Tal we defrost our cold box about once a month.

Clean Air Vents and Condenser Coils
A refrigerator works by transferring heat from inside the box to the outside, dissipating heat through its condenser coils. A condenser works best with lots of fresh cool air around it. All too often a boat’s condenser will be hidden away in some poorly ventilated locker. Keep air vents free of dust or other obstructions and vacuum the condenser coils monthly.


We hang a reflector over our hull where the cold box is located to help keep it cool.

Add More Insulation
You can further increase your fridge’s efficiency by adding more insulation, something that can be done without rebuilding the box. Each of the following  tricks will make a noticeable difference.

Auto Windshield Reflectors
These are cheap and easy to work with. If the sun hits your cold box directly, cut a windshield reflector to size and tape it around the affected area. Keep the silver side out, and your box will stay much cooler. If your box is against the hull, you can also hang a reflector from the toerail to shade the corresponding area of your boat’s topsides. We made a Sunbrella “envelope” with grommets for our “hull reflector” so that it wouldn’t tear apart in wind.

Counter Mat
If the counter over your box feels cool to the touch, a counter mat will add extra insulation to the top of the box and help seal any air gaps around the lid. Get a closed-cell foam exercise mat­—3/8-inch thick with a smooth surface works best—and cut it to size. With a smooth surface, you can still use the area for food prep, and it’s easy to wipe down.
Interior Insulation
Sheets of rigid foam are a quick and easy way to add 1/2-inch to 2 inches of insulation to the inside of your box. (Thinner sheets are good on curved surfaces.) Cut the sheets to size and use silicone caulk to tack them in place. Don’t use the foam on the bottom or the bottom few inches of the walls, where water and spills will collect. Even if you don’t have room on the sidewalls, lining the top of the box and the bottom of the lid will cut down on energy consumption.

Spray Foam
If you have uninsulated voids around your box, you can drill holes in the surrounding joinery and use cans of spray foam to fill them. Spray foam can make a huge mess as it expands, so plan carefully before pulling the trigger. Nonetheless, it’s easier than tearing apart the galley and building a new box.
All in all, it only took us only a couple of days to reorganize our cold box, improve air flow to the compressor, put a stopper in the drain, defrost the cold plate and add some insulation. The total cost was under $150, with plastic bins being the largest single expense. Our improvements gave us 80 percent or more of the benefits of a new cold box, but cost us far less money and time.

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