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Colin A · 29-09-2015, 10:58

It's funny you mention the similar designs I was amazed when I took apart my home freezer one year and found a compressor very similar to the ones I see onboard most boats.
Also I will say in my time in the marine industry I would say less than 20% of the marine refrigeration systems I have seen were water cooled. Almost none on power boats and even most production sailboats seem to use aircooled ones.

**sailorchic34** · 29-09-2015, 10:59

Quote:

Originally Posted by hamburking

Marine fridges usually are water cooled rather than air cooled. Water cooled is much more efficient (theoretically) than air cooled due to the much greater thermal density of water. Think about it...if you burn your hand, will you blow on it, or run it under water? Water pumps can be small and silent, while air pumps (fans) are usually noisy and inefficient. Also, water comes and goes over the side via through hulls...where do you blast the hot air on a boat?

If you read the instructions on most new (land) fridges, you must let it "sit" for at least 1 hour after moving, so that the refrigerant can settle. Sailing will certainly unsettle the refrigerant.

And finally, a humid salt air environment will destroy anything not built specifically for a boat. I lost some great flashlights and other handheld devices this way. The salt air gets into everything. Low grade steel, common on household appliances, doesn't stand a chance.

For small refrigeration systems, water cooled is rarely more efficient then air cooling. You have to factor the energy cost of the circulation pump running into the total energy cost. A small 12V pump is using an amp or so, where a small muffin fan is 0.15 amps give or take. There are times when a water cooled system works well but for a 300-500 btuh system it's almost inconsequential. A simple air cooled system will unless your in the tropics, provide lower operating and maintenance costs.

I have used a dorm fridge for 8 years now and have had no issues with being healed over for hours on end. The thing is the boat actually rocks a bit as it's sailing, so the oil is splashed about in the compressor. It's oil settling that requires some time after setting a fridge in place.

Plus the finish is holding up quite well. Were it on deck, salt spray would be a problem, but I've not seen that issue in 8 years of use.

Cat nap2 · 29-09-2015, 12:17

I have small propane ref on my cat. Does any one else have experience with propane?

alansmith · 29-09-2015, 12:23

Robwilk, for the morons, like me, how much amps a day or per hour will this fridge draw? Great find...will see what kind of power that draws and figure out how to feed it.

A little story. Inherited my dad's house and many of the kitchen appliances soon died within a year or two of his passing. When the microwave died that was above the stove I couldn't find a microwave to fit the "slot" correctly. So, I rethought it. The nice microwaves like his that were a combo microwave and exhaust system were mostly over 1k dollars. So, kitchen was going to be tore down to bare studs anyhow within the next years. So, my sweetheart and I decided to just make a spot near the stove where any 100 dollar generic microwave could sit in the future.

My point tying this all together is this...boaters like to have refridge and freezers. It becomes problematic for size, shape, ac/dc consumption, heat dissipation, volume of space, reliability, cost, and only about a dozen other things...smile. What I like about these type of units is that you can build a space for them traditionally or as in trimarans...put it under the companionway door. When the thing gives up the ghost...throw a new one in ...and for 400 dollars...no brainer. thanks for the link.

nebster · 29-09-2015, 12:26

Wow, you all have gone above and beyond with this thread. Ha!

From an energy consumption perspective, I'd like to look at some of the very best units and see how they measure out. However, I am skeptical that a special fridge will have dramatically better efficiency than a modern residential unit. I see about 1400kWh per day with our fridge, or 60W average demand. We have about 5kWh of usable battery capacity on our RV, and I expect we would double that and switch to lithium for weight. I'm anticipating an embarassment of solar riches, but I wouldn't mind seeing some real-world insolation data from people who've been running big panels for extended periods. That's probably a topic for different thread in a different forum.

I'm not sure I want to "wade in" to the cooling debate, but I am not worried about air cooling in a galley-up configuration on a cat. That air volume is huge and will be constantly exchanged.

Some people mentioned usability. We have a lot of lateral accelerative forces, possibly more than those experienced by a large multihull, and we have adapted our fridge compartment to keep things well-stabilized. No big deal with the right shelving and some common sense.

I see some concern about reliability of 120v units, but here again, there are now thousands if not tens of thousands of residential fridges installed on RVs running full time off a quality inverter. I suspect this was a problem years ago that has passed with inexpensive, beefy, full sine wave inverters.

Someone mentioned steel failure in salt conditions, which was one of the things I wonder about. (Someone else said, no big deal.) My thinking is that, even if we do see some breakdown over the course of a few years, I could afford to put in a new fridge every few years and still come out ahead versus the cost of these marine units.

I've seen the argument for cold air dumping out of a front-door configuration, but the thermal mass of the air is tiny relative to the food, so I think this is pretty much an efficiency rounding error.

So if I'm willing to deal with the battery and solar requirements, and put up with generator runs from time to time like I do today, then it sounds like this decision boils down to space and fitment, which admittedly is a huge deal.

Finally, someone asked what kind of "living aboard" we would do. I don't know for sure, but I think it'll be a mix of marina, anchorage, and maybe one or two significant passages. We will spend either one or two years before returning home to land.

Thanks guys!

dochip · 29-09-2015, 12:44

The Great Harbour Trawlers, manufactured in Florida, use all "residential" AC equipment ... fridges, freezers, etc. and they are popular high-end very sea-worthy boats.

jreiter190 · 29-09-2015, 12:50

Just talked to Engel and asked how large a unit I could fit into available space on my boat. I settled on model MT27F, which is a 22qt. A.c./d.c. refrigerator OR freezer, and draws LESS than 1amp! When in port , I'll run it as a fridge, and when cruising, as a freezer, stuffed with steaks , chops and fillets. The initial hit is $850 plus tax at West Marine though I could most likely save a few bucks buying on line. But who do I return it to if it takes a dump? By keeping the receipt, I can exchange it anywhere in the States. It only hurts when you take the money out of your wallet! For not much more, they have 40qt. models and larger. Some with more room than I , buy two 40 qts. and run one as a freezer, which needn't be handy, and the other as a fridge

onestepcsy37 · 29-09-2015, 13:04

bobw100ton. The CSY37 I believe is being discussed was built by Vanost with a well insulated box that could be supported with a keel cooled (no strainers, pump or open thru-hulls) Frigoboat unit with freezer section for well under 75 Ahrs per day. Adler Barber units do not set and standards for efficiency, just price.

Bobw100ton - as a long time owner of a CSY 37 I can firmly state that this boat, as well as all CSY's were built in Clearwater FL by CSY. And I can humbly state that it is one of the best designed and constructed boats a cruising sailor could ever want. Having been designed for Caribbean cruising it has considerable insulation in the fridge/freezer area. I removed the original Crosby engine drive water cooled fridge system and replaced it with an Adler Barbour air cooled system. AB is not cheap as far as that type of system is concerned and they have an excellent reputation. Mine is going on 11 years and has never experienced a single problem. Does everything I ask of it. It runs entirely off one 130 watt solar panel, albeit in Florida/Bahamas.

Sailorchic34, thanks for posting. I for one think you have done a great job with your boat and always welcome your advice.

hamburking.
Marine fridges usually are water cooled rather than air cooled. Water cooled is much more efficient (theoretically) than air cooled due to the much greater thermal density of water.

Hamburking - From my experience most marine fridges are air cooled, not water cooled. Water cooling is not necessarily more efficient and it always has more "parts" to go wrong and suck up power. When I bought my Adler Barbour it came with optional water cooling. I decided to just use the air cooling part and only add the water if I needed it. Ten+ years in Florida/Bahamas and I have not felt the need to add it. If fridge guru Richard Kollman will post here he recommends air over water and will give you his reasons why.

PaulinOz · 29-09-2015, 13:30

I met a family of 4 that traveled from Europe to Australia over past 5 years. From day 1 had 400 lt Bosch Domestic Fridge/Freezer, Electric cook top and oven and electric BBQ. Pile of Solar and good electrical management with 6kW of Inverter. (Lagoon 500) Zero problems in 5 years with any of the domestic equipment. The marine equipment was another story.

My current boat has 2 x 130 lt and 1 x 80 lt fridge and 1 x 100 lt Freezer all air cooled marine units. Replacement cost AUD $7,500

These all could be replaced by 1 x 440 lt fridge/freezer. Running off the inverter. Cost AUD $1500 that leaves AUD $6000 which will buy a lot of extra Solar, Batteries and Inverter to run it. Other main advantage modern domestic units are frost free, emptying and defrosting 4 x units every 2 months in the tropics is a pain in the condenser.

Why have I not done it yet,current refrigeration is only 2 years old, to fit in a large domestic unit in to current layout means taking a saw to cabinetry.

**a64pilot** · 29-09-2015, 13:54

I believe the frost free part is done literally by resistance heating, and if that's true I can see how that part uses more energy than the compressor, but I believe there are units that have an energy saving setting that turns off the frost free part.
I think even the seals may be heated?

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darylat8750 · 29-09-2015, 13:56

The Dominic in my trawler gave up 5 years ago in Mexico. I went to a big box store and bought an 11 cu. ft. high efficiency 24 in wide ref/freezer with separate doors. Less than $300 US. When looking find a basic model with no external fan (just enough radiating area so it doesn't need one) and no self defrost. I do have a large battery bank but with much wide screen TV for she who must be obeyed and computers ect we use less than 300 amps per day. If we move the boat every day we don't need the gen set. If several days in one spot we average an hour a day. Solar is still on the wish list.... I was worried about the amount of heat that the refridgerator adds to the interior of the boat but it seems insignificant to us.

I did add simple pin type door locks.

Sardean · 29-09-2015, 13:59

I have two ICEER brand fridge freezers on my cat. They are the most efficient I have ever seen.

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accomplice · 29-09-2015, 14:04

We have both a household-style ice maker and a full holding-plate marine fridge and freezer.

Here are my findings.

1. The marine fridge and freezer are much more space efficient. The shape of available places to put stuff on a boat is rarely a huge rectangle. Having a custom fridge is important to get full space utilization. RVs, by comparison, tend to be more "square" (yes, I know not all are). The custom fridge/freezer would only be a fraction of its present size if it had to be rectangular.

2. The insulation on the custom fridge is much better than the pre-bought unit. There probably are some domestic units that are well insulated, but they're not the inexpensive ones.

3. Our custom units have sea-water cooled condensers. Some people say that water cooling is no more efficient, and possibly less efficient, than air cooling. I have found that in cold waters (50s F), the water cooled is MUCH more efficient, whereas in warmer waters (80F) the efficiency advantage drops off and may reverse. Granted, the air temperature in the warmer waters was probably ~20+ degrees different too, but the refrigerator requires only ~45-60 minutes a day of run-time in Maine vs 90-120 minutes/day in the Carribbean.

4. The custom units have large holding plates. Since the refrigeration is powered by battery, I find it preferable to put the energy into the holding plates when the genset or engine is running and minimize the battery draw (less generator run-time to charge-up batteries when at anchor or on passage). Most domestic units are designed with evaporator plates and smaller compressors -- an almost continuous draw at a low rate. This is the case with our icemaker. Unless I'm connected to shore power, or expect to be motoring a lot over the coming days, I won't even bother to turn it on.

5. The icemaker does have a small latch on the door, but its shape and closure makes it far harder to use at sea. If we're heeled the wrong way, I won't attempt to open it. The door on the fridge is better secured and the storage is through a narrower portal that helps prevents all the contents from coming out at me. Also, the freezer has a top-loading option that can be both more energy conserving and easier to use at sea, if less desirable at anchor.