Fridge and freezer temperatures

[Yellowjacket]

Clarification: Temps given for the box were taken with independent thermometers, the inexpesive kind you buy at the hardware store, not the control thermometer which reads from the center of the eutectic plates. When the plates are at -25ºC, ther freezer box is at about -14ºC. The plates will warm to -17ºC befgore the compressor turns back on, and the box may go from -14 to -13, still too warm for rock-hard ice cream, but my lettuce isn't frozen.

[Auspicious]

You're really going to like the separate compressors and thermostats. Insulation is key, but a major job.

Originally Posted by CassidyNZ

But our crossings are normally 7 to 10 days so the freezer will enhance this process. I usually sail with two unskilled, inexperienced crew who almost always have some level of mal-de-mer to contend with and having pre-cooked meals will save me having to cook a full dinner every day.

Peachy. Beyond the scope of your question I find yogurt is a big help for unsettled stomachs. I carry Tetra boxes of chicken broth for dinner. As stomachs settle I use the broth to make things like broccoli soup, tortellini soup, cooking rice, Asian noodles, glazed carrots, gravy, night watch midnights, ... I don't usually come home with any broth left.

Most of the time I try to have a prepped or at least easy dinner every other night. Those days I make a full breakfast. Yogurt/berry/muffins breakfast days in between get a bigger dinner.

As soon as there is room in the fridge I make pasta for dinner and hard cook eggs - same water, same time, same fuel. 12 minutes is 12 minutes. Raw eggs of course are not in the fridge. Roast pork loin also as soon as there is room in the fridge for leftovers (roast for dinner, sliced thin for sandwiches, shredded with jarred barbecue sauce for another dinner). Food safety guidelines say to defrost frozen food in the fridge but often there isn't space. *sigh* Sometimes we have to do the best we can.

The challenge is to keep people/crew from foraging in the fridge and ultimately increasing power consumption due to pulling the temperatures back down. I use a snack bag to keep people out of the fridge. Remember people eat from boredom as much as hunger.

Disciplined mise en place cuts down on opening and closing the fridge and saves energy. It's the culinary version of thinking eight moves ahead in chess. I call it "constructive laziness."

I mentioned having two freezers in my own boat. The second is an Engel buried under the main berth. We've found that for sustained cruising freezer space is more important than fridge. The Engel is smaller than our main freezer. By the time there is room in the main freezer it's also time to change the sheets and check water in the house bank batteries, also under the main berth. Empty the Engel into the main freezer and turn it off. Constructive laziness. Usually end up doing a big cook a day or so after transfer for cooking ahead. Sometimes it's a day or two ahead to make room for the Engel food if my wife declares "time to change the sheets." We carry a pressure canner and home canned food is shelf stable - freezer to pantry. "What's the plan honey?" "Cooking today and tomorrow, canning tomorrow, changing the sheets the next day, then we tack to lay the Azores."

sail fast and eat well, dave

[DMCantor]

On our boat, the temp-sensing module is located near the top of the freezer box. As everyone knows, cold air is denser and sinks. When we set our controller at -5C, we get much colder temperatures at the bottom of the box - which is where most of our stuff is, most of the time.


Also, I think the -20C recommendation is aimed as much at preserving taste and texture for extended periods as it is at managing safety. Certainly overkill for the 2-3 weeks at a time that we typically keep frozen foods. In any event, in 10 years of cruising we've never had a problem.

[Oceanride007]

I would like -12degC in Freezer and 4 degC in Fridge, Also got a portable that could be either. Ideally I need fridge filled in morning rather than at night.

Had a fridge mechanic on board recently to resurrect the Freezer, ie change the filter, suck out and recharge, came back many times but best we could do was -12degC at 100% duty cycle, I opted for more gas, say -10Deg in case of some tiny leak.

Out cruising now with insufficient battery power, ie can't afford 100% duty cycle, -6DegC keeps everything cold but not cold enough to get stuff frozen while plenty of power when Solar is available.


Have now opted to place all frozen stuff in Portable and run it at -14DegC in the day and wind it up to -5DegC during night. This strategy stops me from getting low voltage alarms that would occur if battery goes down 60Ah.


Of course I need battery upgrade, but boat going to storage soon. This compromise will stay in place till then. Yes its important to know what you can get away with.

[Grattaway]

Cassidy hi

We operate a cold storage business here in NZ and also have chillers and freezers on board our boat
Your proposed chiller temp should be fine but just be aware if you load up with a lot of warm product two things can happen
Firstly product already in the fridge can warm up - the temperature in the space is averaging out
Secondly as product gets down towards storage temp the temp drop slows down
and size of product is important - a big bottle of juice will take longer the chill than 2 small ones and cardboard packaging slows down chilling

Freezer temps -12c is your minimum storage temp here in NZ - so we operate freezers at -15 or -18 C to ensure we always meet -12 and thereby keep officials (MPI) and customers (Foodstuffs and Countdown) happy

But it depends upon what you freeze
water - once its frozen its frozen
beef lamb, fruit cheese butter -12c is Ok for product preservation and if you are doing short term 10 - 15 days your proposed temp is probably ok
Icecream - a bit tricky usually -18c but however you like your ice cream is what works
Chicken - this is a product that carries lots of bugs even in NZ and if in the freezer I want it at lower than -12 always. Personally I dont carry on board
Fish - ideal temp is below -20 - fish has an enzyme in it that keeps breaking down product until you get it down to about -60c. So keep fish in the freezer for more than a few weeks and its deteriorating fast. Commercially for us -22c is our "3 month life" storage temp but short term (days) -12c will be ok

and again remember that putting warm product in can raise average temp and to much or many temp variations will reduce quality - easy to do in a small chiller or freezer box. Contra also applies - thawing product in the fridge will help hold fridge temps and reduce compressor load
and full space works better than half full

Regards Wayne

[MicHughV]

...refrigeration on a boat is a tricky navigational hazard.

...what most people don't understand is:

...refrigeration is designed not to put cold in ...but rather to take heat out
...so one must factor in the insulation qualities of the icebox/fridge/freezer... top/loading or side side loading, etc, and the capability of the chosen refrigeration unit.
If you have poor insulation, etc, small compressor, etc, you are pretty much farting against the wind.

....more often than not, the fridge/freezer on a lot of boats is inadequately insulated, too big and the fridge unit to small, etc.....especially the air-cooled variety. This means the fridge unit has to run nearly 24/7 to maintain coldness. The same air-cooled variety can also be had with a water cooled condenser, but I have yet to see one in practice.

Regardless, it becomes a case of required amperage for a given fridge performance.

Engine driven fridge systems is a completely different animal.

..the small air cooled variety fridge systems found on most boats will consume 5-7 amps/hr...and unless one has solar panels or wind generator this will quickly suck down a battery or batteries...

..many boats....my Beneteau included, have the fridge and freezer adjacent to each other with a small hole between them. Additionally, the condenser unit is inside a cockpit locker often covered with all sorts of cruising junk and little air movement.

...I have found that by adding some store bought insulation panels, typically 3/4 to 1" thick and lining the fridge/freezer with these, I can double the performance of a fridge/freezer system at a small sacrifice in interior space.

The thermostat control for both fridge and freezer is only in one box...the freezer side.
To ensure I have adequate freezing temps in the freezer section, I keep a small bottle of water in there, which typically freezes over. As long as this stays frozen, I assume all is good. Additionally, I try to make ice on a daily basis....as long as I'm making ice for evening cocktails, I am assuming all is well.
I do have a small portable temp. gauge in there, but I am dubious to it's accuracy.

...It took some time to find a happy balance between the thermostat control and actual performance. I can't say for sure what the temps are at any given time, but the freezer stays frozen and the fridge stays cold and the unit is not working overly hard.

..To make all this a happy fridge/freezer requires several solar panels and large battery bank, without which, you will be running a generator every day for a long time.

..At the end of the day, enjoying a cold beer on a boat requires enormous effort, planing and diligence. I have yet to calculate the cost of solar panels vs. the enjoyment of a cold beer, but I suspect it is a substantial number.

Ah well, we must do what we must...

[CassidyNZ]

Originally Posted by Grattaway

Cassidy hi

We operate a cold storage business here in NZ and also have chillers and freezers on board our boat
Your proposed chiller temp should be fine but just be aware if you load up with a lot of warm product two things can happen
Firstly product already in the fridge can warm up - the temperature in the space is averaging out
Secondly as product gets down towards storage temp the temp drop slows down
and size of product is important - a big bottle of juice will take longer the chill than 2 small ones and cardboard packaging slows down chilling

Freezer temps -12c is your minimum storage temp here in NZ - so we operate freezers at -15 or -18 C to ensure we always meet -12 and thereby keep officials (MPI) and customers (Foodstuffs and Countdown) happy

But it depends upon what you freeze
water - once its frozen its frozen
beef lamb, fruit cheese butter -12c is Ok for product preservation and if you are doing short term 10 - 15 days your proposed temp is probably ok
Icecream - a bit tricky usually -18c but however you like your ice cream is what works
Chicken - this is a product that carries lots of bugs even in NZ and if in the freezer I want it at lower than -12 always. Personally I dont carry on board
Fish - ideal temp is below -20 - fish has an enzyme in it that keeps breaking down product until you get it down to about -60c. So keep fish in the freezer for more than a few weeks and its deteriorating fast. Commercially for us -22c is our "3 month life" storage temp but short term (days) -12c will be ok

and again remember that putting warm product in can raise average temp and to much or many temp variations will reduce quality - easy to do in a small chiller or freezer box. Contra also applies - thawing product in the fridge will help hold fridge temps and reduce compressor load
and full space works better than half full

Regards Wayne

Thanks Wayne, useful info for my calcs. Our ridge works fine, now about 5 years old. I keep the temps between 4.5 and 7 degrees, don’t like drinks too cold.

The freezer is new so practising with temps now. We normally sail around our home in January/February, this year we’re going aboard in a week or two and will be out there on and off until end Feb. Will know the performance soon enough.

[CassidyNZ]

Originally Posted by MicHughV

...refrigeration on a boat is a tricky navigational hazard.

...what most people don't understand is:

...refrigeration is designed not to put cold in ...but rather to take heat out
...so one must factor in the insulation qualities of the icebox/fridge/freezer... top/loading or side side loading, etc, and the capability of the chosen refrigeration unit.
If you have poor insulation, etc, small compressor, etc, you are pretty much farting against the wind.

....more often than not, the fridge/freezer on a lot of boats is inadequately insulated, too big and the fridge unit to small, etc.....especially the air-cooled variety. This means the fridge unit has to run nearly 24/7 to maintain coldness. The same air-cooled variety can also be had with a water cooled condenser, but I have yet to see one in practice.

Regardless, it becomes a case of required amperage for a given fridge performance.

Engine driven fridge systems is a completely different animal.

..the small air cooled variety fridge systems found on most boats will consume 5-7 amps/hr...and unless one has solar panels or wind generator this will quickly suck down a battery or batteries...

..many boats....my Beneteau included, have the fridge and freezer adjacent to each other with a small hole between them. Additionally, the condenser unit is inside a cockpit locker often covered with all sorts of cruising junk and little air movement.

...I have found that by adding some store bought insulation panels, typically 3/4 to 1" thick and lining the fridge/freezer with these, I can double the performance of a fridge/freezer system at a small sacrifice in interior space.

The thermostat control for both fridge and freezer is only in one box...the freezer side.
To ensure I have adequate freezing temps in the freezer section, I keep a small bottle of water in there, which typically freezes over. As long as this stays frozen, I assume all is good. Additionally, I try to make ice on a daily basis....as long as I'm making ice for evening cocktails, I am assuming all is well.
I do have a small portable temp. gauge in there, but I am dubious to it's accuracy.

...It took some time to find a happy balance between the thermostat control and actual performance. I can't say for sure what the temps are at any given time, but the freezer stays frozen and the fridge stays cold and the unit is not working overly hard.

..To make all this a happy fridge/freezer requires several solar panels and large battery bank, without which, you will be running a generator every day for a long time.

..At the end of the day, enjoying a cold beer on a boat requires enormous effort, planing and diligence. I have yet to calculate the cost of solar panels vs. the enjoyment of a cold beer, but I suspect it is a substantial number.

Ah well, we must do what we must...

The “boxes” on my boat are side by side, top loading and deep enough that I can’t easily reach the bottom (and I’m 6’4”) so I’ve changed them ever so slightly. In the fridge I cut a large hole in the front wall (into the galley), designed, built and installed two fully insulated stainless steel drawers. A shelf halfway down the box now seperates the space into three divisions each easily accessible. No unloading half the contents to reach stuff at the bottom. As I said, this has been operational for a number of years and does a great job.

In the freezer I have installed the same shelf halfway down so the space is about half that of the fridge with an evaporator about 50% larger. Under the floor, at this time I have 15 litres of water in plastic bottles frozen solid.

When both units are running they draw between 8 and 9 amps and run about a 40% duty cycle. My solar array (about 850W) on a good sunny day easily delivers 35 amps so running these units is easy as. All the power used overnight is usually recovered by midday.

So keeping things cold is really not a chore, it’s just really about getting it right, not spoiling the taste of beer (too cold) whilst at the same time not poisoning my crew (not cold enough)

[Auspicious]

Originally Posted by Grattaway

We operate a cold storage business here in NZ and also have chillers and freezers on board our boat

Incredibly helpful. Thank you. I'm careful with chicken - not giving it up. *grin* Fish enzymes are news to me. That may change some of my provisioning and meal planning. Fortunately I don't have to think about chilling fresh fish. I'm the poster boy for why it's called "fishing" and not "catching."

[MicHughV]

Yes, I built my first boat....I had big dreams, but little money. To this end I built my " icebox" with the best insulation material I could afford and nothing less than 6" of it anywhere. Despite all this, it was an " ice eater". Prior to a trip, I would pack it to the brim with the last piece of ice shaving I could squeeze in there, but two weeks was about maximum I could expect from this setup. Interestingly enough, the icebox was fitted with a drain hose led to a gallon milk jug in the bilge. Once a day I would empty this jug, which was often filled to the top with melted ice water, which surprised me to know how quickly ice was melting inside there.

One warm beer too many and the writing was on the wall as fellow sailors were tiring of my " bring some ice" requests.

For my research I spoke with many sailors and inspected every boat fridge system I could lay my eyes on....but I quickly came to the conclusion that having a cold beer on my boat was going to be an expensive proposition. First came the actual device, then the extra batteries and then the wind charger to keep it all going.

Having built my own icebox, I knew the wall thickness and insulation within and was rather surprised at how well a small fridge system (back in those days it was called an Adler-Barber fridge system) worked.

In later boats, I discovered the wall thickness of the fridge/freezer units were not up to snuff, which led me to placing my own layer of insulation inside, with notable results.

My second boat had the engine driven fridge system. The fridge was fitted with a massive cold plate, and a large compressor was belted off the engine. It worked incredibly well, but required the engine be run at least twice a day, which I can attribute to a lack of insulation in the box.

The Beneteau, as described before, has the connected fridge/freezer system and a large solar panel array, but the compressor is located in a poorly ventilated cockpit locker and seemed to be running 24/7.

Without question, the best advice I could give anyone with a fridge/freezer system onboard, is to add some insulation inside. A variety of insulated foam panels are easily sourced and these can be cut to shape and glued inside one's respective box.

I am not a fridge expert, but I have come to learn that the insulation qualities of most sailboat fridge boxes is rather poor and adding an inch of insulated material can and will make a remarkable difference in performance at little cost to space. On my boat, the difference has cut the run time of the compressor by half and the freezer side of my box can freeze solid.

I wish I had some actually temps to note here, but I don't. I can only say that adding the insulation can freeze everything rock hard in the freezer

[Aircool]

Reading all of you is pretty scary...guess I will die soon lol

I keep my portable dometic cf50 at -5c ( pretty much the best I am getting) and keep chicken brest, fish filet and many other goods for months! Never saw a difference in taste or texture.

I do know its borderline and since we are on a 2 year trip down the caribbean I just order an insulated cover for it. I will see in the next couple how it go

[Aircool]

Originally Posted by Aircool

Reading all of you is pretty scary...guess I will die soon lol

I keep my portable dometic cf50 at -5c ( pretty much the best I am getting) and keep chicken brest, fish filet and many other goods for months! Never saw a difference in taste or texture.

I do know its borderline and since we are on a 2 year trip down the caribbean I just order an insulated cover for it. I will see in the next couple how it go

Little update,

I put the cover on the freezer and change the thermometer location. It was at the bottom of the cooler and Its now in the midle.

Now reading -12c. I guess its not only the cover that made the difference! Pretty sure the cold air can not circulate. I have a piece of hypervent that I will put a the bottom of the freezer. BTW I know that cold falls down but it is what it is lol