As a kid in the eighties my friends family had a small yacht. I recall their fridge ran off gas. I know most fridges now days use electricity and lots of it. We are planning to do some extended cruising in a number of years and wondered what are the best options for refrigeration.

We currently only have a 40w solar panel and an 105 amp hour battery which does nicely for vhf, stereo, galley pump, lights and starter motor.

Guess we would almost need to double that setup ?

I know a guy who has a 50L 12VDC fridge on board and a flexible 120w solar panel. He makes this solar panel provide all his needs by repositioning the panel every day and during the day as the sun moves or boat swings with the tide/wind. I'm not sure of his total battery capacity but I'm sure it would be a lot more than 120AH. If you are going to have your panes fixed in place with the odd shadow falling across them you will need more panels. This guy is full time live aboard and never (not very often) has the opportunity to top up with shore power.

The more insulation on the fridge the better and some manufactures also have covers you can zip the fridge up in.

Thin Insulation = More solar panels

The other trick is to keep the fridge as full as possible at all times even if you have to fill it with bottles of water, by doing so you increase the thermal mass and things keep colder for longer with less cycling.

Fridges are a never ending battle.
The only true way to get on top of them is to have a completely separate power and charging system.
The power the fridge takes needs to be replaced ASAP , basically if your fridge draws 5 amps per hour you need to replace the power with the same 5 amps.
The other option is keep replacing your deep cycle battery's every one or two years as it seems they don't really like to deep cycle!
I have seen some fridges that well insulated that the stay cold for up to 12 hours.......this is a very important factor on what charge you will need.

There was a thread a couple of months ago about fridge power. I had a quick look but cannot find it.

On my boat I have a 120 litre fridge with a eutetic unit and two 55kW panels. The panels provide adequate power for the fridge, but we generally need a bit more power to cover the other demands such as lights, radio, instruments etc. This is easily covered by a short run of the engine each day, which we would do anyway to heat water for the shower.

Refrigeration will almost certainly be the biggest user of 12V power on your boat - assuming you've done the basics like replaced all your lighting with LEDs. So if you're "just coping OK" now, you'll probably need to beef up both your charging ability and your battery capacity. I managed OK on my S&S34 which had a built-in fridge, old insulation, with 240W of solar panels and about 200AH house battery. On the current boat, we've got 180W of solar and about 400AH house; we have a built-in fridge and a Waeco that we use for a freezer. We usually go for 2-4 days with no engine before we need a charge.

Make sure you have a good 12V supply to the fridge compressor. Measure the voltage at the compressor when it's running - you shouldn't lose more than half a volt compared to the battery voltage. And make sure your condenser unit is well ventilated.

If you currently have no refrigeration at all, you might be best off with a WAECO or similar, if you can find room for it. These don't draw too much power, and you can set them to run at either fridge or freezer temperature.

The alternative is to make yourself a fridge box, and install one of the modular refrigeration units to keep it cold. If you go this way, the more insulation you can install the better - preferably at least 80mm thick polyurethane foam (100mm or more for a freezer). You need to have the foam fully enclosed to prevent any condensation - once it gets wet, it doesn't insulate very well.

Spend a bit of time scrolling through here:
http://www.kollmann-marine.com/Refrigeration/

Thanks for that link QLDCruiser, I registered an account .
I do want to ask a question in here .
Tropical waters and keel coolers for refrigeration are they any advantage compared to normal water cool systems in tropical waters.
Also not sure but thought in tropical waters is there a variation in water temp let say from the sea surface to 1 meter below . where a keel cool would be fitted.
I do like the idea of less moving parts one less cooling pump to stop working.



This will become my fridge / freezer and I would like to make a difference when fitting insulation so it uses the lest amount of energy as possible.
I did look at Aerogel space loft but its reasonably expensive and was wondger what would be a good choice with out busting the bank
Here a link to aerogel

http://www.ebay.com.au/itm/Aspen-Aerogel-SPACELOFT-Insulation-Hydrophobic-Mat-Per-Linear-Foot-10mm-/180860317203
Areo gel is also in perth so theres a freight factor to the east coast
its roughly around $105 M2 plus freight for anything under a full roll
So other insulation would be recommended?

I have a eutetic unit that is powered by a compressor mounted on the motor with a belt back to the flywheel
It takes about 40 mins to get cold but once cold it requires only 20 mins a day to stay icey cold.

running the engine also provides hot water, I have 60w solar panel to top up the battery during the day

Using the motor as the power source for the fridge saves the expense of larger solar panels and extra batteries.

Eutetic is is the best and most engery efficient system for boats.

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seabird said..
I have a eutetic unit that is powered by a compressor mounted on the motor with a belt back to the flywheel
It takes about 40 mins to get cold but once cold it requires only 20 mins a day to stay icey cold.

running the engine also provides hot water, I have 60w solar panel to top up the battery during the day

Using the motor as the power source for the fridge saves the expense of larger solar panels and extra batteries.

Eutetic is is the best and most engery efficient system for boats.

I dont mind that idea I charted a benny once that was set up the same worked really well and one of my problems is space for a solar panels
the old Bukh DV 20 is reasonably cheap to run to boot

Thanks for all the tips, sounds like it's going to be an even bigger deal than installing the loo.

The Waeco cfx35 might be the go.
Power draw seems quite low if I'm reading it correctly: 0.77Ah/h
So it continuously draws 0.77A ?

HGO2: Here's a link to Aerogel discussion - started in 2011, with most recent posts this year:
www.cruisersforum.com/forums/f115/aerogel-spaceloft-insulation-for-fridge-freezer-58888.html

I've only skimmed the thread, but the big question seems to be how it would stand up over an extended period, and whether it would absorb water and lose insulation qualities.

Seabird: I don't agree about eutectic. It was in common use twenty years ago, but since Danfoss released efficient 12V compressors, electric systems have dominated. Both are using stored energy - in the eutectic case you're storing the cold in the plate; in the DC, you're using the battery storage system that your boat needs to have anyway (although probably beefed-up). Last week we were in Cairns marina opposite a boat with pure eutectic refrigeration. Even though he was on shore power, he was having to run his engine for an hour every day to maintain the fridge. I couldn't imagine anything worse!

Keensailor: The Waeco draws about 2-3 amps when the compressor is running. The 0.77 i guess is their estimate for the average draw over 24 hours, given that it cycles on and off.

HG02: you also mentioned water-cooled condensers. My take on these is that yes, they are definitely more efficient than air-cooled, but it is a big source of failure through corrosion. There's not much to go wrong with an air-cooled unit, apart from the need to replace the fan every 5-10 years.

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keensailor said..
The Waeco cfx35 might be the go.
Power draw seems quite low if I'm reading it correctly: 0.77Ah/h
So it continuously draws 0.77A ?

I have 40 lt 12v fridge in my 4wd with the same Danfoss compressor. The compressor is a 48w motor so on 12 v it draws 4amps when running.

If you work on the motor running 50% of the time it will draw 48amps a day ( 4x24/2)
So you would probably need 120w panel plus 120amp battery as a minimum.
But you would need 6-8 hours of sunlight a day to stay infront of demand.
You will kill the battery quickly if you are regularly drawing below 50% of storage.

I'm not sure how Waeco get .77amp they must work on the motor running only 20% of the time. If you cruise the tropics it will be running closer to 50% of the time.

i ripped the eutetic unit out of my boat and made the old fidge into an ice box and i have a waeco 50 litre in the aft cabin it does the job in tassie summer and really uses bugger all power.
the old fridge if we are cruising for a few days is so well insulated i put 3 bags of ice in her and 4 plastic milk bottles frozen in the deep freeze at home and still had 70% of my ice after 5 days using it as the drinks fridge so opening it constantly i put a themometer in there and it maintained a temp of around 1-2 degrees
i have just wired a 12v computer fan into the ice box to move the air around and hopefully make it even better.

The BD35 can be configured to run at different RPMs, which would amount to a range of power settings. I have the Waeco CF40, and it draws 3.4A when running (just checked - sorry for misleading earlier post!!). We run it at -12C, and although I've never measured it, I'm guessing it runs around half of the time, so 1.7AH/H.

The Waeco specs (0.87AH for CF40, 0.77 for CFX35) are for ambient 32C, fridge set at 5C. I think they're a bit optimistic.

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QLDCruiser said..
HG02: you also mentioned water-cooled condensers. My take on these is that yes, they are definitely more efficient than air-cooled, but it is a big source of failure through corrosion. There's not much to go wrong with an air-cooled unit, apart from the need to replace the fan every 5-10 years.

These type of keel coolers with an anode.
I just wonder tropical waters the water temps is around 22 /24 degrees how would they hold up.
I know theres the other style with a water pump

You are probably right when you say theres not much to go wrong with the fan cooled units
K.I.S.S. is always better
*******
What would you all recommend as far as insulation goes when building a fridge box ?

I'm sure the cooler would work OK in tropical waters - in fact that's where they'd have the most advantage over air cooling. There's also one that replaces your existing galley sink drain through-hull, so no need for an extra hole in the boat:
http://isotherm-parts.com/asu-cooling-units-sp-cooled-c-4_10_61_67.html

However my own preference, following the KISS principle, would be for air cooling with particular attention paid to ventilation of the condenser unit - maybe with ducting to clear air with an extra computer fan.

For insulation, you need polyurethane foam - it has a better R-value for given thickness than any other type. Depending on the application you might use precut sheets, or 2-part mix. Best to enclose it in heavy plastic film to keep moisture out. The Kollman forum would be the place to ask about specific products.

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QLDCruiser said..
I'm sure the cooler would work OK in tropical waters - in fact that's where they'd have the most advantage over air cooling. There's also one that replaces your existing galley sink drain through-hull, so no need for an extra hole in the boat:
http://isotherm-parts.com/asu-cooling-units-sp-cooled-c-4_10_61_67.html

However my own preference, following the KISS principle, would be for air cooling with particular attention paid to ventilation of the condenser unit - maybe with ducting to clear air with an extra computer fan.

For insulation, you need polyurethane foam - it has a better R-value for given thickness than any other type. Depending on the application you might use precut sheets, or 2-part mix. Best to enclose it in heavy plastic film to keep moisture out. The Kollman forum would be the place to ask about specific products.

This old head area will be my new fridge and freezer. the keel cooler will be replacing outlet side head sea cock. I am thinking of insulating it and line it
The original fridge cabinet will be modified so a sink can be fitted beside a day fridge cooled by frozen bottles of water taken from the above freezer.So its only opened a couple of times a day



Moving the fridge lid across to the left and modifying the cabinet so a sink can be fitted on the left hand side of the cabinet.
Ill reuse the lid and replace the bench top with the same material as the stove cabinet on the opposite side and make a very thick insulated day fridge on the right hand side of this cabinet

I have a Waeco 12v fridge. Once cooled down, I put a couple of frozen water bottles and a couple of frozen stews in ice cream containers in with the other contents to get it going, it runs for about 3-4 minutes in 20. Specs say 4 amps an hour running continuously so it uses a bit less than an amp an hour. A lot more before it cools down.

I try to run my engine for an hour each day when at sea. That plus my 40 watt panel seems to do the trick but I haven't tried it for more than a few days. My house batteries are two 105 amp/hr gells, 210 amp/hr total.

Most will probably know this but bagged ice usually is frozen just below freezing temp a good practice if your weekend sailor is buy it and take it home and put it in the freezer for the night. The freezer will lowers the ices temp a bit more making the ice last longer