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Interesting comments Toltec. After 50 years of cruising we have come full circle back to our original concept of KISS. So we agree with you on freezers. As my beloved is wont to say, if you want all the comforts of home, then stay home.

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We freeze down 3 x Fiji water bottles ( because they are square) they last up to 3 days with care and are still cold enough for another couple of days, (no beer stored, food only. Most of the time it is not all that hard to find someone with a deepfreeze to re-freeze them. Many of the big fizzys have freezer room for Africa.

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Kiss is how we run the boat we hardly ever have problems when we are away most Christmas holidays are between 4 to 6 weeks we do try to get salt ice when away over that time advantage of fresh water is you can drink it or use it for a shower

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we have a small 12v compressor fridge with a thermostat, at the present running off the house batteries. I am thinking of installing a separate battery with its own 100w solar panel and regulator just to run the fridge, that way the house batteries will be kept up for running nav lights and autopilot etc, and I suspect that the fridge will survive on that one panel and battery anyway but if not at least it will only run one battery down plus I could divert more panels to that battery once the house batterys are full.  I think at anchor we will have plenty of power but when on passage we may need a little extra input to cover ais gps tillerpilot and lights running overnight.   Will have around 5 to 600 w of solar and with 2 big  house batterys , 1 even bigger winch  battery and 1 average size for the fridge separated with 3 solar regulators.  On passage the anchor  winch battery and panel could be diverted to supplement either of the other 2 banks. Not a lot of engine amps available with 2 x 8 amps from the outboards and perhaps another 8 amps from a small  generator, so cloudy days or lots of shade may mean having to shut down the fridge at times.  Has anyone had success running or constructing a 12v alternator from a small generator size motor to give 30 or more amps?

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I run an EvaKool  (a fiberglass box, camping chest fridge, like a Waeco).

It is very efficient. We make ice cream. It has been continuously running for many years now and runs just off solar.

I would not have Water cooled, eutetic type systems on board anymore, and have just recently removed a large version (separate fridge and freezer) from a vessel and replaced it with a Waeco. The drop in power usage has been huge and the getting rid of all the extra plumbing and through hulls a real bonus. If you run two units you can run one as a freezer only or turn one off when not needed. They will auto switch between 240v and 12/24v as well, you just leave it plugged in to everything !

 

ps I run 200 watts of solar and a air x. Which runs everything except a heater in winter marinas.

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I run an EvaKool  (a fiberglass box, camping chest fridge, like a Waeco).

It is very efficient. We make ice cream. It has been continuously running for many years now and runs just off solar.

I would not have Water cooled, eutetic type systems on board anymore, and have just recently removed a large version (separate fridge and freezer) from a vessel and replaced it with a Waeco. The drop in power usage has been huge and the getting rid of all the extra plumbing and through hulls a real bonus. If you run two units you can run one as a freezer only or turn one off when not needed. They will auto switch between 240v and 12/24v as well, you just leave it plugged in to everything !

 

ps I run 200 watts of solar and a air x. Which runs everything except a heater in winter marinas.

Part of the reason I use (and sell) Ozefridge units. Water cooled, but no thru hulls (fresh water), no fancy plumbing.

Proper eutectic systems use the least power of all, when set up correctly. My own unit is a 290ltr fridge AND a 290 Ltr freezer, BOTH run off a single Ozefridge fresh water cooled unit. It draws around 5 amps, and, on the equator, ran about 30% of the time. Yes, we had icecream. The unit is 12/240v, so can run from shore power. The 12v side has some smarts - yachts normally have lots of power (while motoring, on shore power, or genset or solar is on) or little power. When the voltage is charging (over 13v for example) the Ozefridge will turn on, and keep the unit at its coldest setting, so when the power is not available, it will not have to run for the longest possible time, as the eutectic solution thaws keeping the unit cold.

Our unit uses around 30-50 amp hours per 24 hours, for both the fridge and freezer combined - remember the capacity, they are big! The actual usage depends on the outside temp, what you have recently loaded into it, etc etc, hence the variance.

It is still the most efficient unit I've seen, but would be interested in the capacity and current draw specs from your EvaKool?

Oh, and the Ozefridge unit itself starts at around $1200, plus the eutectic tanks from around $600. They come pregassed, and you can fit them pretty easily yourself. see http://www.neptunes-gear.com/index.php/refrigeration.html if you're interested, or give me a PM or call.

Matt

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 is a 290ltr fridge AND a 290 Ltr freezer,

Holy crap. I now know where I can stash my entire boat if it gets to hot :lol: :lol: :lol:

 

We have 40lts all up.

 

 

IB do you know the amp it draws while running?

What he said, I'd like to know as well.

 

I did like Idlers comment about panels and wind does all but heaters. Each comment like that Is see I think 'cool, a little more giving the stereo a big nudge time'  :thumbup: 

 

Assuming the place I'm trying to buy batteries from decides they want to sell batteries. I am beginning to wonder.

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Those who do not have water cooled units, usually have great difficulty in keeping the units working properly, or efficiently when they are in the Tropics. If you are have no intention of leaving NZ, then you can get away with a non water cooled unit here. However, even here in the cooler climes, a water cooled unit is so much more efficient and if you pop to the Supermarket mid Holiday cruise, pulling down warm foods freshly put into the Freezer takes far less energy.

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...about 24 amp (hours)...in high ambient temps..its only 60 litres though. (For the two of us that has been heaps).

I have to say that 30 amp (hours) for 580 liters is extraordinary....

I have never had any problems with the system in "the tropics"...and dont know of any one that has had problems with the aluminium chiller plate type fridge system. I have heard this only as a myth.

   The only difference is the chilling solution in the eutetectic type (as a cool storage) and the use of a water instead of air in the condenser.  The use of water can be not quite as efficient as made out due to day night temperature cycling. In the case of tanked water the water as a larger thermal mass can hold a higher temperature than the ambient air over night. When used with sea water the water temperature can also be higher than the air temperature over night. 

There is also a loss in the transfer of cooling from the refrigeration circuit to the liquid circuit.

I am not sure what the difference (if any) of power draw of a pump versus fan is ...

By Ozefridges own charts the "motor on" difference for the two examples above in their same cabinet is two hours over a 24 hour period. Given an equivalent in my size that would be a difference of 2 amps over 24 hours. 

   For me that is not enough to justify the added hassle of pipes and pumps. I personally dont like having through hulls running with pumped sea water for extended times ...especially when the boat has nobody aboard. Something that has to happen with a fridge system that is sea water cooled. If a hose comes off or splits the result can be (has been) disastrous.

Obviously the tanked system (usually your drinking water tank) alleviates sinking as a problem BUT......now if a hose comes off or splits.......

I guess I am a bit fussy...I have no through hulls on my boat at all .

  When asked about the whole fridge thing, I am happy to say the the water cooled eutectic system that is well set up with perfectly working thermostats are more efficient.

But the difference in power draw and cost is more than an extra solar panel or two, The eutectic tanks, pump(s) and hoses weight balances out against said panels...and the panels power can be used for other purposes when not needed....all without the obvious extra complexity and potential danger...

 

(Oh and by the way...my boat has clocked out at 46 degrees on a very hot Melbourne Summers day...........we have never managed to get it any where near that hot when traveling north )

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If we are going to discuss this in any meaningful manner, 1st we must get the units correct to make any sense. The rate of power consumption is Amps. The amount of power consumed per day is amp hours, or AH.

I disagree that water cooling loses refrigeration efficiency - water has a much better thermal conductivity than air.

However, even more important than any of this is cabinet design and insulation type and thickness. A poor cabinet is not going to be any good regardless of what you use.

On an old boat with polystyrene insulation behind the cabinetry, a unit like the EvaKool might be the easiest and cheapest solution.

Ripping out cabinets and replacing them can easily result in a bill of 10k or so by completion.

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Sorry IT lazy on my part...(hours)  added by edit...

I will repeat this in case you missed it..

 

  When asked about the whole fridge thing, I am happy to say the the water cooled eutectic system that is well set up with perfectly working thermostats are more efficient.

 

But have also explained why I dont think those efficiency gains are worth it .

​It is also worth bearing in mind that if the greatest value of the eutetic system (the reason why it was originally used for sailing vessels all those years ago ) is the ability to "hold cold mass" from times when energy is easily available and release it at other times, (The original eutetic systems were almost exclusively run by having the compressor direct coupled to the motor) then

The advent of cheap solar panels and indeed even cheaper more reliable AGM batteries now achieves the same thing. Sure the motor run time on a aluminium chiller plate type fridge freezer is marginally more...but to be blunt...who cares ? They are quiet and the cost difference more than makes up for a slightly earlier replacement for a simpler and more reliable system.

 

 

I was also kind with regards to cost because the cost comparison assumes that the cabinetry is already there for a eutectic but not for an aluminium. 

Built from new, the cost difference is obviously huge.

 

For the added enlightenment of all of us, I would love to hear more first hand experiences from people about both types. 

 

To add another thing to the mix, I would be interested also in hearing from people who are using standard domestic fridges.

I have seen a massive increase in their use (usually the under bench type) with dedicated inverters.  ... lets keep the comments on this "speculation free"...

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On an old boat with polystyrene insulation behind the cabinetry, a unit like the EvaKool might be the easiest and cheapest solution.

When I looked into insulation when making my Fridge box, I was shocked at how poorly Polystyrene performed and how thick one would need to make a Panel. Polyurathane Expanding Foam was far far superior and even then, there were differences with different types of expanding foams. Most certainly it is well worth doing home work on the Insulation before using one. You can also buy premade urathane panelling specifically for refridgeration. Don't use Polystyrene.

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Cost of starting from scratch could easily go past 15k.  I have just done it.

 

Old cabinet was only 35mm insulation panels stuck to the stainless box.  I decided to rip it out and start again.

Big decision was weather to put in an ozefridge and utetic system or stick with the DIY option.  The decision was made or me when the existing cabinetry was removed and i found that the existing stainless box was nearly excatly what i was told i should build so that was an instant 5k saving.  But it was also 20mm to narrow to fit the eutetic plates that were required.  I ended up staying with the isotherm compressor and getting copper pipe braised to three sides of the stainless box.

 

New cabinetry built with 180mm on the bottom and 100 on the sides and top and new digital temerature controller and i am keeping freezer at -18 running about 10% of the time at 5amps draw so i am hoping for a daily usage of around 30amp ours (it is about 90litre freezer and 50 litre fridge).  Pretty impressed so far.

 

But with ne doing all the removal work, and sanding/repainting myself I still spent around 7k and that doenst include the cost of the compresor.

 

Adding in the new compressor and plates, plus the 5k for a unit if it was needs and the bill would have topped 15.

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And as a comparison I bought a good as new 12 v compressor type fridge with a small built in freezer and thermostat, (retail around $1000) for only $50 from a garage sale. I have added 40mm blue polystyrene insulation to the top , bottom and sides and plywood over that.  It works fine and even at  new price I would be happy.   I have had several of these fridges in other boats and also have a small chest freezer type one that runs on 24v nominally but still works as a fridge on 12v, none of them have ever caused me any trouble.  Having 100s of litres of fridge space is nice but we just don,t really need it or have  the room, nor do we catch heaps of fish to put in it.. 

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These guys do one of the best ranges of units ready for permanent installation

Www.iceer.com.au . Most of the Queensland charter cats are fitted with them.

 

Re insulation, much better to go with panels rather than the foaming type, more consistent properties and the foaming type is bad for moisture take up.

Calder's boat bible has a test of different types of insulation with some interesting results

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more consistent properties and the foaming type is bad for moisture take up.

No not true at all. It depends on the type of Polyurathane foam you get and the one that the panels are made from is the one you need and the one KM fills bouys with to make them sink proof. The last thing KM wants is the Foam to absorb water. It defeats the entire purpose of filling them.

I made my fridge this way. Made the panels and then poured in the Foam. Great for utilizing spaces you cannot fit out using pre made panels. In saying that though, pre made panels are easier to work with in many situations.

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I don't agree with the idea above that just adding solar is the solution to run a thin plate fridge/freezer.

Every boat I've been on is short of electricity, especially on passage, when everything is working hard. There is no silver bullet. Solar has been a huge benefit for cruising boats, but it's not 100 percent reliable - it doesn't work at night, and it's not always sunny. Wind gens the same, although often more useful in the tropics and on passage. Whatever you do a mix of solutions provides the most reliable generation.

If you only coastal cruise, maybe have a wind vane rather than an auto pilot, small crew, and or not long term, then the choices are not so critical, and a small chilly bin type fridge is likely fine.

If you sail long distances, in remote locations, with limited provisioning opportunities, then power consumption including refrigeration becomes critical. Thats why I ended up with both an engine driven eutectic system, AND an electric eutectic system, completely separate for redundancy, but fitted to the same cabinet. Not cheap, but suited our purpose.

Of course, if you are a traditional sailor, you don't need electricity, or an engine, at all.

Most fall between the two extremes. :-)

People must pick what suits their situation and requirements best.

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