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Refrigeration Conservation

11K views 42 replies 15 participants last post by  Cruisingdad 
#1 ·
Refrigeration Conservation... (smile)...​

Well, as this is the cruising forum, I felt it might be beneficial to discuss refrigeration techniques that have worked for us to keep your 12v costs at a minimum. I am not the final expert on this (or anything in life, for that matter), so I urge anyone with other ideas to feel free and chip in.

Refrigeration. It is one of those things that I have had old salts tell me you do not need, but I will be darned if I will do without. There would be a mutiny of kids, wife, and dogs (not sure who would lead it either!!). But, refrigeration has the distinction of being about the biggest electrical hog on a boat on the hook. Many of the modern coastal production cruisers use Adler-Barbor refrigeration, as I do. Short of sticking an ice-pick through it (no laughs... it COULD happen to you!!), it has served us well on our many trips. The general budget for a AB system is about 50-60 ah/day. With that in mind, even large 12v systems will begin to get taxed before long. Thus, here are some key ways you can do your own Refrigeration Conservation:

1) Stick your head inside the box and look around for holes. Sound silly? I bet if you own a production boat (or almost any boat) you will see the refrigeration lines come right into the box and are not sealed!! It is like leaving the door cracked or lid up! Depending on the size, you can use MG caulk or even the can of Foam Stuff to seal it in. If you use the latter, let it dry completely before you cut it to shape. Acetone cleans it up when wet. A putty knife cuts to shape when dry.

2) Plug the drain (foot drain) with a cork or similair object. It might not save you much, but I see no reason to cool the water under the boat. Keep the T-Hull closed too - though I am sure this is a practice most people do anyways.

3) Use thick plastic sheets to cover the inside of the front door. Remember when you would walk through the old grocery stores and you had to reach through hanging plastic to get something that was refrigerated? Make a similair system on your boat. Thick plastic, cut in strips, screw it just to the inside of the door at the top.

4) Resist opening the front door. Even with the plastic strips, when you open the front door the cold air comes straight out. On a passage, I drop a little screw through the "lock hole" so it cannot be opened by those who forget (ie, the kids). On long runs, pack the things you will need most on top through the top-load.

5) Double insulate. Styrofoam, for all of its negatives on the environment, is one of the best insulators and is dirt cheap. I would not do this unless the original box was not well insulated (as this takes up some room in the box), but it is a consideration.

6) Use a "heat blanket" on top. You know the aluminum emergency heat blankets you can buy at about any backpacking store? They keep in cold too. They are cheap. Put one aross the top of your box (on the inside) where you have to push it to the side to get the item(s) you need.

7) Keep your fridge stocked. The more stuff in there, the better. A super-stocked fridge (once it has gotten all of the items cold) will maintain its own temperature better. The cold items act as their own cold plate. You also seriously minimize the air inside, which is most apt to dissapear when you open the door.

I hope some of these tricks help some of you as you gear up to punch off - whether around the bay or around the horn. They have worked for us.

Great sailing and fair winds -

- CD
 
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#27 ·
The Engel looks like a good solution for minimal refrigeration needs. The model Freesail uses is actually a 1.6 cubic boot box which can be cooled to 40 degrees with a 77 degree ambient temperature on less than 1 amp/hour assuming the box stays closed. Obviously, how often it is opened for one of those 60 beers will influence the amps used greatly. Running 100% of the time it draws about 2.75 amps which would be a very worst case scenario.
Here are the power curves for various temps outside and inside the box.
http://128.121.204.56/engel/MT45F curve.jpg
 
#28 ·
The secret is to freeze a jug a water and put that in another cooler with the beers......... :)
 
#29 ·
Freesail99 said:
The secret is to freeze a jug a water and put that in another cooler with the beers......... :)
You aren't wrong with that. If you aren't going to pack the fridge with nearly frozen food (meaning you can turn it RIGHT down for the better part of a week if you have a decently insulated box), you should throw in a block of ice in a rubber bag to hold the melted water.

Alternatively, throw ice into a Koolatron (3-4 amp draw), pack it with cold beers...uh, supplies...and then unplug it and wrap it in a sleeping bag or a Mylar "space blanket". I've gone two days this way on the old, fridgeless boat keeping things at bacteria-discouraging temperatures.

Of course, a rethink of what actually requires refrigeration is helpful, as well. Old cruising books talk about getting fresh eggs (never refrigerated) and coating them...they last six weeks. Certain vegetables, if kept ventilated, last a long time. Bread needs a bin, and so on. Cheese can be preserved in jars. Milk can be UHT. And so on. If we just needed refrigeration for keeping canned beverages cold, we wouldn't need a lot of refrigeration, or rather, we could run it less extravagantly.

At least I could...I don't drink on passage! :rolleyes:
 
#30 · (Edited)
We have an Engel upright, undercounter AC/DC refrigerator built into the galley cabinetry. It is a front access however, an option Nauticat offered over the standard top access units. I believe Engel only makes portable units now though.

We do like the convenience of a front access unit but agree it is not the most energy efficient - due to amperage draw and the fact that cold air drops out each time the door is opened.

One tip we have that works for our Igloo cooler - used for beverages when cruising for a few days, is to freeze water in those 7 litre silver mylar wine bags - contained in those cheap wine boxes. We never drink the stuff, only vintage wines for us. But, our dockmates do and save the empties for us.

They're reusable - the pour spout/cap pops off for refilling. Just place in your home freezer a couple days before packing the cooler - 2 bags last for three days with us - before having to buy blocks as replacement, and no water mess when they thaw. We do have a full enclosure Sunbrella cover for the cooler, with a built-in cushion seat -which helps with the insulation.
 
#31 ·
I have an Engel on my boat... Love the little beastie... since it works like a champ. Since it is top loading, it tends to lose very little cold air when it is opened.
 
#32 · (Edited)
Just a little note regarding top-loading doors: using a top door instead of a front-loading door definitely saves the cold air but always use a backup method to keep the door open, especially in a seaway. I learned the hard way that the latch that keeps a top-loading door propped open can self-unlatch if the boat makes a quick rolling motion in the same direction as the lid opens. And when the boat comes back the other way that heavily insulated door gets moving pretty fast--fast enough to cut off a finger. Always use a bungee cord or other secure method to keep the door from slamming shut should the normal latch fail.

Regards,
Mark
 
#33 ·
Good point Mark, but not much of a worry for me, since the refrigerator I have is a tiny Engel unit... and it is installed along the long axis of the boat...so rolling isn't much of an issue.
 
#34 ·
If you are in the market for a replacement, Performance Cruising's Gemini 105MC comes with a 4cuft LP refer like RVs use - Made by Dometic, but others have products too. Usually you can cruise for 2 weeks from a 20lb tank including stove use. Nice thing -- not one amphr spent on refrigeration.
 
#35 ·
TOMINDC2 said:
If you are in the market for a replacement, Performance Cruising's Gemini 105MC comes with a 4cuft LP refer like RVs use - Made by Dometic, but others have products too. Usually you can cruise for 2 weeks from a 20lb tank including stove use. Nice thing -- not one amphr spent on refrigeration.
Nice idea and all, but generally unwise on most sailboats. IIRC, the refrigerator in question uses an ammonia-based refrigerant, and works by heating the ammonia. However, this refrigerator needs to be kept fairly level to work properly. While this works on a boat like the Gemini 105MC, which is a multihull, specifically a catamaran, which heels about 10˚ maximum... on a monohull, this refrigerator would probably be a fire risk, and definitely a waste of money.

In fact, I even doubt that this refrigerator would work on most trimarans, which heel about 15˚ maximum under sail.
 
#36 ·
insulating paint

regarding insulation ,I was associated several years ago with a company which sold an insulating paint called ceramicote.Space shuttle technology came up with a latex based paint containing ceramic spheres which when applied in a 6mil thick layer had the same insulating properties as 6" of styrofoam.It is easily applied with a brush or roller or even a slinger type paint sprayer.applied internally and/or externally to an ice box or refrigerator it will drastically increase the efficiency of the box.It will adhere to plastics ,fiberglass and all types of metal.

House Paint for Insulating Home, Roof, Siding, Ceilings, Walls, Attic Radiant Barrier Paint
 
#38 ·
We have the Adler-Barbor cold plate 12v system. On the way back in from our first sail we heard a screeching noise coming from under the cockpit. After much concern (was it our prop?) we tracked it down to the reefer compressor. According to the guys who looked at it, we need a whole new compressor unit. I don't know enough about it to disagree, so they are trying to track down a replacement (our unit is probably 15 years old). It sounded like a bearing failed.

Anyway, what's the general operation of these units? How long do you need to run them for? I thought you ran the unit until you reached the desired temp (we have thermometers in our reefer) and then once it reached a certain temp you turned it off. Then once it warmed up some, you ran it again. Is this correct?
 
#39 ·
sailingdog said:
Nice idea and all, but generally unwise on most sailboats. IIRC, the refrigerator in question uses an ammonia-based refrigerant, and works by heating the ammonia. However, this refrigerator needs to be kept fairly level to work properly. While this works on a boat like the Gemini 105MC, which is a multihull, specifically a catamaran, which heels about 10˚ maximum... on a monohull, this refrigerator would probably be a fire risk, and definitely a waste of money.

In fact, I even doubt that this refrigerator would work on most trimarans, which heel about 15˚ maximum under sail.
SD,

Sounds like a paid up boat fire insurance policy with an propane powered refer could turn a sailing momohull into a liquid asset?
 
#40 ·
labatt said:
Anyway, what's the general operation of these units? How long do you need to run them for? I thought you ran the unit until you reached the desired temp (we have thermometers in our reefer) and then once it reached a certain temp you turned it off. Then once it warmed up some, you ran it again. Is this correct?
Labatt,

Almost. The thermostat is the control for the cooling compressor an if it's working properly it is automatic. Set it "thermostat" to the desired temperature and forget it.
 
#41 ·
RickBowman said:
SD,

Sounds like a paid up boat fire insurance policy with an propane powered refer could turn a sailing momohull into a liquid asset?
Yup... but I doubt you could get insurance if they knew you were installing a propane powered refrigerator... ;)
 
#42 ·
Improving energy efficiency of refridgerators on board.

Hello,

As a future investment i'm thinking of getting a compressor refridgerator wich has an automatic feature that freezes icepacks at full power for ~3 hours and the shuts off - cooling the contents for zero power draw - until a sensor discovers renewed need to freeze the packs. (Indel Isotherm ASU).
Quite nifty , i must say.

I currently still use a thermoelectric cooler on my boat.
I greatly improved the cooling by mounting a stronger 12 volt(PC fan) and insulating the inside with 3cm thick 'finnfoam' , thats a special hot compressed styrofoam that doesn' crumble when cut.

Now it cools up to 35 °c under the surrounting temp. (used to only manage 15°c). the volume though now is down to 20 liters(from 30).

Its also important to ensure that there is cool air circulating around the unit.
12v Deck vents .

I am planing to install a thermostat or timer - And see if that brings down the 4 amp per hour draw.

Erik.
 
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