How to Quickly Defrost Your Boat Refrigerator

One key to keeping your boat refrigerator running efficiently is to defrost whenever there is 1/4 inch of frost built up.  In the Sea of Cortez (surrounded by desert), I had to defrost about once a month. Now, in extremely humid southern Florida, it’s about once every 10 days.

Defrost your Fridge the Easy Way

This doesn’t have to be a huge chore. With a hairdryer and inverter (or shore power), I could defrost the large refrigerator on our previous boat in about 35 minutes.  (Be sure to read my notes at the bottom of this article if you don’t already have a hairdryer on board.)

It takes a little longer — about 45 minutes — on our current boat as the refrigerator manufacturer recommends not using a dryer. Apparently it could warp plastic parts inside the refrigerator. So even though the total time is longer, I’m not actually working on it the whole time.

In this age of frost-free refrigerators, many of us have never manually defrosted a refrigerator. Or we have only dim memories of mom doing it when we were a kid.  It took me a while to learn how to quickly defrost the refrigerator, so I didn’t dread having to do it.  It helps if all your food is already in bins.  If you’re in a hot climate, you have to work fast so that food won’t spoil.

My Defrosting Method

Here’s how I defrost my fridge, step-by-step. It starts with emptying the fridge.

Empty the Fridge

• Put your most perishable foods (frozen foods, milk) in the best coolers you have.  I like soft-sided coolers on the boat because they’re easy to store. The Polar Bear 24-can and 48-can coolers (from Amazon) aren’t cheap. But they really work well both for defrosting and getting stuff back to the boat from a distant store. If the items are already frozen, they’ll stay that way for a couple of hours even without extra ice if you’ve got a good cooler.
• Take all your bins out of the refrigerator.  Quickly check to see if any need cleaning out, either from spills or spoiled food. Don’t wait. Take care of it now.  Cover the bins with quilts, towels, pillows, sweatshirts or whatever else you have to insulate the contents.
• Turn off the refrigerator and remove all dividers.  If there is a drain in the bottom, open it (see my article on why the drain should be closed for everyday operation).

Melt the Ice

• If you can, use a hairdryer to melt the ice build-up.  Be careful not to actually get the hairdryer in any water, due to the electrocution risk.  Many times, the hairdryer will cut off before all the ice is melted – this is a safety feature to keep it from getting too hot.  Turn it off for a few minutes and let it cool off, then use it again.
• If you’re not using a hairdryer, my next choice to put a reusable hot pack in the freezer section. As it cools down, I replace it with another. Four about perfectly do it. (Read more about these or buy on Amazon). I close the door/lid to keep that heat in.
• If the freezer compartment is metal, you can alternately put a pan of boiling water in it to speed up the defrosting.
• If you have nothing else, point a fan at the inside of the fridge.
• After about five minutes, see if ice starts breaking off.
• Break off chunks of ice from the chill plate as possible — I do it every time I change the heat pack — and dump them in the sink.  It is much easier to dry out the refrigerator if you don’t let them melt in the bottom of the refrigerator, and it also keeps them from continuing to chill the refrigerator.
• Be very careful around the chill plate or freezer compartment not to puncture a tube, but use a dull knife or piece of dowel to gently poke ice out of hard-to-reach places.  Never use force, as you’re likely to break something and then you’ll be without a refrigerator.
• When all else fails, you can pour hot water over a stubborn bit of ice – but this will create a lot more work to mop it all out of the bottom of the refrigerator if you don’t have a drain.

Finish the Job

• Totally dry out the refrigerator, close the drain and replace any dividers before putting food back in the refrigerator.  Any moisture left in the refrigerator will quickly turn to frost and ice, necessitating another defrosting job.
• ONE EXTRA STEP WILL SAVE A LOT OF WORK NEXT TIME: Spray the cool plate with cooking spray (like Pam) before you put everything back in. When you next defrost, the ice will come off much more easily and in big chunks! This has made it much easier for me. And it ensures that frozen food doesn’t stick to the compartment walls, either.
• Don’t forget to turn the refrigerator back on!

Using a Hair Dryer to Defrost

A FEW NOTES ABOUT USING A HAIRDRYER ON BOARD:  If you don’t already use a hairdryer on board — and most cruisers have hair styles that don’t require one — there are a couple of things to consider:

• Most blow dryers are 1875 watts, although most mini-dryers are 1600 watts.  Both are going to require a 2000-watt inverter and won’t work on the little inverters that plug into a cigarette lighter.  You can also run one off shore power or a generator that puts out at least 2000 watts.
• I actually prefer using the mini dryers as the shorter nozzle is easier to use in the confines of a refrigerator and it’s easier to store.  You don’t need one with a lot of features — I bought the cheapest one I could find.
• Try to find a dryer with a long enough cord that you don’t have to use an extension cord — or make sure that you’ve got an extension cord on board.
• What’s the power draw to use a hair dryer on an inverter?  If you use an 1600 watt dryer on high for a total of 6 minutes (and if you keep the refrigerator defrosted regularly, I doubt if you’ll need to use it that long), you’ll use a little under 14 amp-hours from a 12-volt battery bank.  If you don’t have a lot of solar or wind-generation power, this can be a good project on a day when you’re going to be motoring a bit so that you’ll have plenty of power to replenish the batteries.
• And, of course, you can now find 12 volt hair dryers (Amazon) as well. But they don’t appear to be highly rated.

Alternative Method

Another cruiser suggested another easy hack. She used a microwave (although you can just boil water on the stove too).

After emptying the freezer and the shelf immediately below the freezer compartment, spread a large trash bag over it and as far back and “up the wall” as possible. This will catch much of the drippings and ice chunk. Then I “nuke” (or heat) about 2 cups of water close to boiling. Pour it into a small metal pan and put that into the freezer. If you rotate 2 cups in the microwave, you can swap out the cooler water and reheat it.

Gently pry the ice off with your fingers or carefully with a chopstick or other dull implement until the job is done. A sponge under the freezer compartment will soak up the melting water. But the plastic bag catches much of it too. Carefully take the bag out and “dump” it into the cockpit.

Some thrifty cruisers harvest the leftover water to refill lead acid batteries.

Other cruisers have even had success turning off the freezer before bed and leaving the door closed. In the morning, just remove the fallen ice.

A spare turkey baster is another great tool to remove the last bits of water. Even better, if you have a access to a pump, you can pour warm water over the cold plates and pump it out.

Defrost Your Boat Fridge – It Isn’t Hard

I hope I convinced you this important task isn’t difficult. And doing it will make your fridge more efficient–always a worthy goal for any cruising boat.

What’s your favorite method? Share in the comments.

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