Refrigration and Trawlers

"If you want to save money, charter."

When I started on the airline , an old Captain commented.

If it Flies , Floats , or F***s its better to rent it than buy it.

Truer words were never spoken.

Having had propane, engine compressor driven and DC refrigeration on several different boats, I decided on the last for my present boat.*

Pioneer has two fridges, 130 liter and 70 liter and a 90 liter freezer.**These are all stand alone, off the shelf units. They are different brands, (Isotherm fridges, Evakool freezer) but all use the Danfoss compressor system. BD35 in the fridges and BD50 in the freezer.

Removal for repair is easy (the freezer had an internal*corrosion problem) and efficiency is remarkable.*Mine run on 24V but they will also run on 12V. In summer, two 80W solar panels will keep them operating all day*- and top up the batteries.

In winter, when the sun is lower, I sometimes need to run the genset for an hour a day,*of course,*the lower ambient temp means less load on the refrigeration.

On the marina, I simply have the battery charger on.**

The freezer is set to -18degC and cycles between this and -13degC. which is cold enough to keep everything solid. However, I've discovered that it is much more efficient when full, so I fill the larger gaps with water-filled plastic bottles. The cycle time is normally 9 minutes on and*11 minutes off.

As an experiment, filled with water bottles at ambient temp, (around 24degC),it took 3.5 days to get down to*to -18deg C, so having stuff prefrozen makes a huge difference.

With DC refrigeration, a E meter or battery state-of-charge meter is very important. Battery banks and charging systems must be up to the job.

Hope this helps.
Jeff b

With DC refrigeration, a E meter or battery state-of-charge meter is very important. Battery banks and charging systems must be up to the job.


True , this is the hassle as many fridges will use close to 100A a day.

That requires 200A of batt bank per day with the hassle that it takes a LOOONG time to being a bat set back to 100% full. OR the cruiser slow death method of 80%full to 50%full with an E meter.

Spiral batts can be charged faster so a big alt and pri$y batts are a start.

Least engine time is an engine driven pump and "Cold Plates (eutetic plates).

This usually requires a custom box and the eutetic plated eat a bunch of room inside the box.

On our 90/90 we get 3 days of 5F freezer and only require 2 hours of engine time BUT 6 inches of freon blown insulation and almost 10,000BTU of cold plate turn a big hole in the boat into a modest sized top loading fridge and freezer.

A custom box DC large eutetic plates , and a very fancy monitoring and charge system is probably the simplest way to go, short of propane.

Most distance cruisers are all in sail boats , where the heel angle makes propane really hard (EZ on multihulls tho) as the entire unit must be gimboled.

IF a fridge location on a trawler is well above the WL, a simple tray , say 4 to 6 inches deep and vented overboard will handle the possibility of some vented gas before the safety cuts off the gas.

On our Trawler the unit is simply located on the self draining after deck.In a custom box to keep the rain off. A nice part about propane is the life of the unit , ours is at least from the 1960's and works great.

-- Edited by FF on Thursday 4th of February 2010 05:50:18 AM

Another course of action that may be the simplest , but not the cheapest is a fridge freezer that is made for "Off Grid " use.

Top of the line is Sunfrost with 12v or 24v danfloss compressors and lots of good insulation.

Nova Cool is another brand that is common.

Much of this stuff is "house sized" not RV sized so getting it aboard might not be easy.

The electric loading is 1/2 to 1/4 a common house fridge , and the efficiency is even higher when the 10-18% of most inverters , and the poorer performance on non sine wave juice are figured in.

www.sunfrost.com/

You get what you pay for .

Alt energy folks figure its 300% more efficient (and cheaper) to NOT use power than do the big recharging charging dance.

FF

When going to boats, refrigeration was one of thing hardest things to figure out. I knew I wanted several things. 1 was to have a large refrigeration area to keep drinks cold, meat, produce and stuff like that. and 2 was a large freezer so I could store a lot of food for long term taking advantage of cheap pricing in some places while saving money in areas where food is more expensive. I planned on long offshore voyages. On a sailboat that means one of 2 ways. Either 12v or engine driven. Neither is ideal. And neither I or my wife likes hanging upside down in a cold box trying to find something. But front opening boxes waste energy. So when I first started looking at trawlers in yachtworld and seeing all those home style refrigerators, I was like "amazed" wondering how that could be. I am still wondering.

To me a boat refrigeration system is "EXPENSIVE".
I know some will say , no mine ain't. And I am sure your right. But what do you use it for and where do you go with it. Many don't leave the marina. So a home style 110v is ok. but get out for a few days and you have a warm box and spoiled food.
If you have 12v box. then you probably have dead batteries or you run the engine or genset a lot to charge them up. It is inefficient.
I think the best combination is a well insulated box with both a 12 or 24 v evaporator and a engine driven cold plate system. And this is of course expensive. But while motoring the cold is free.... sorta, and when at anchor a robust battery bank and charging system with multiple sources is needed. That is large batteries, large charging systems, and solar and or wind power to keep them charged up. You could just go with that but then when it breaks down, and it will, the engine driven plates will be there for backup. If you just have a small box and not a lot of food, then it might not matter much, but if you have a freezer full of steaks, fish, butter, ice cream, chicken... etc it will mean a lot of money thrown away, and more important, eating canned food for a while. Yuck.
The new Isotherm and frigoboat stainless steel boxes with danforth compressors are nice. And can be run with 12v or 110v. But the box size is smaller. A well designed 4" insulated frige and 6" freezer with both dc and engine systems is expensive, but IMO worth is for the piece of mind and versatility. It is only cost effective IMO is you are living aboard and cruising full time.
Bob

We don't have dead batteries because we manage amps in and amps out carefully. Our two fridges and one freezer use 25-30 ah per day at 24V.

In summer, if we are anchored and not going anywhere, the 2 x 80W solar panels pretty well take care the refrigeration (and everything else) and in winter we may need to run the genset once a day for*one hour max.

I can't see the point of having an engine driven system as well as 12/24V. When the engine is running, there is plenty of electricity available to run the refrigeration.

An engine driven compressor is an "open" system which requires considerable maintenance and regassing since it relies on seals at the compressor shaft to keep the gas in. In my experience, and I have owned both types, the engine-driven system is much more likely to fail than the Danfoss 12/24V compressor which*is hermetic - totally sealed.

Isothem have a ASU system which detects when the engine is running (higher voltage) and goes into "supercool" mode so that sort of negates the argument that an engine driven compressor will pull down faster.

All the Danfoss 12/24V compressors and components are available in kit form with evaporator plates to suit many different applications. You can even have brine tanks if you wish, and a choice of air or water cooling - or even a cooling loop fitted to a thruhull. Just build a well-insulated box and choose and fit the approriate components. They are even pre-gassed and snap together.

When on a marina, we simply plug into shore power and use the batterycharger to keep the fridges and freezer running.

Examples of what is available can be found at this website www.fridgetech.co.nz. but all this stuff is available world wide.

-- Edited by Bendit on Wednesday 26th of May 2010 02:55:30 PM

-- Edited by Bendit on Wednesday 26th of May 2010 03:01:28 PM

-- Edited by Bendit on Wednesday 26th of May 2010 03:02:19 PM

Jeff,
Agree with you.
I have a combination of domestic and danfoss equipment.
In the wheeel house I have a 90 lt frig (all frig) and a 90 lt freezer both LG.(240 V)
On the back deck I have 2 x 110 lt Eva Cool frig / freezers (55 lt frig/55 lt freezer) that I run on 24 V be it either shore power supply or inverter battery.
They chew a bit of power but I run my main eng or gen some hours each day when I am cruising so all is charged up. I am yet to install some solar panels but they are on the to do list just to decrease the gen run time.
I am a motor boater and do not mind the hum of a nice quiet running diesel engine.

Benn

On a previous boat I had a eutectic under the seats but it stopped working so I purchased a 5 cubic ft upright freezer and a 5 cubic ft I think they were bar fridge and ran them off an inverter

I had a 12 volt generator and I would run this for 1 hour morning and lunchtime and 2 hours at night to keep the batteries charged.

It all worked very well and a lot cheaper to set up than expensive 12 volt gear.

Allan

It seems you are going about it backwards?* First address the power options and then refrigeration as the power is the key.* We have a 10 KW main gen, 5 KW cruise gen off the main 671, three 8 D batteries with 3000 kw inverter, propane and a cold plate.*If you know the power source and weather tied to a dock, under way or anchoring then you can address the refrigeration options.

Since we have most of the options, I would rank then in the following order highest to lowest;

3 way AC/DC/propane two on the back deck
2 way AC/DC main galley refrigerator no place to vent.
120 only refrigerator would not have
cold plate have but do not use as it takes to much power, and*we use as storage.

Anyway, have the power sources and then decide the kind of refrigeration.***


-- Edited by Phil Fill on Thursday 27th of May 2010 12:17:49 PM

Hi Benn,
I also have an Evakool freezer (90L) in the cockpit. I should have bought a "marinised" one since I have had a few corrosion problems and had to get a new evaporator plate. I didn't know that they did marinised versions until after I bought it!

The wheelhouse frig (with an icebox) is an Isotherm 70L and the galley frig (no icebox) is an Isotherm 130L. The galley frig is incredibly efficient. I reckon its cycle rate is only about 25% running and 75% fan only. The total average current draw for all units is 1.1 amps at 24V.

Jeff b

Jeff , Please post the PRICE of your system ,it might horrify the Sears fridge folks!

Jeff,
The 2 x 110 lt Eva Kool frig/freezers I have are on my back deck and have been for the past 5 years, still going strong. At $1700.00 each this was the cheapest way I could do it even with building them my self.(didn't have the time).

Have been a bit slack so must open the covers and clean the evaps before I depart on my next cruise.

Benn

Benn,
They look great, almost built in. Mine is just a snug fit into a 1" recess in the deck.
FF, 6 years ago the three units cost USD 2,100 approx.
Jeff b

I've been on a boat for a week that had cold plate fridge and freezer, and running it one hour in the morning and one in the afternoon was enough to keep it cold as long as you didn't open them (that means running the genny).* We kept all beer and soft drinks in a cooler full of ice, and bought as much as we could carry from on shore*every two days.* That was the best I've seen.

Other boats with cold plates required more time to charge the plates.* I guess the one boat must have been new or whatever.

There is no perfect solution, but if you are cruising without shore power, and you have a generator that you need to run in the morning to power the stove and / or microwave etc, and you need to run at night for A/C, then the cold plate is the way to go.* You just have to keep it closed and not treat it as a home fridge where you can open the door every time you need a cold beer.

Now, if I'm underway 5 hours a day, I'd get a 12vDC/12vAC model since I can run it on 12v while I'm underway.* When I'm on the hook I will cut it off, and if I'm at a marina I will run it on 120.

I think FF has it right that no matter what you choose you are looking at the same problem: removing heat from a box.* It will take the same amount of power in the end to remove the heat (and make it cold) from the box whether you remove it slowly over time or do it quickly to a heat sink and let it remove the heat from the box.* Conservation of energy will always be true, so the best thing you can do is make sure the enclosure is well insulated and well sealed.* How you remove the heat from that enclosure is a matter of preference and habit of cruising.

One solution not often used is to select the eutetic solution to suit your engine run time.

A higher temp freeze melt point will allow refrigeration with short , more frequent run times.

The noisemaker 3 -4+ times a day folks.

A lower temp solution will suit the 2+ hour engine run folks.

Either way the BIGGEST compressor will be a help at the start of the re freeze , but of little help at the later stages.

The reason is ice is an insulator , so as the tubing inside the plate gets a thick coat of ice , heat removal is slowed.

FF I understand you.* Once the plates get frozen then nothing will get them colder.* My point is that they can get frozen by an hour of generator use.

Once the plates get frozen then nothing will get them colder. My point is that they can get frozen by an hour of generator use.


Plates are like batts , they come in a variety of sizes.

The Adler Barbour engine drive plates could be as large as 20 X 20 and 3 inches thick , then there was the SS freezer U bank at almost 6000 btu.

Even with the almost 10 hp of a converted car air cond compressor could not freeze these totally in an hour. Ice forming internally was the reason.

The heat leak is constant , the heat removal with a plate only lasts till there is nothing left to melt,

so the bigger the plate , the longer you can go.

As an experiment Mike had a custom copper sheet evaporator made up. (instead of simple copper tubing) The unit curved to fit inside the 20 sq , so there was no place the fluid was more than about 3/4 thick from the copper .

The reduction in pump down time was beyond belief , about 15 min from a warm box , in a shop with only enough electric for a 1 Hp compressor.What it might do with the engine drive was never learned as the Danfloss units were being introduced and many boaters care more about initial price than have a need for a long term cruising system .

You bet cold plates will get colder than "frozen" or 0 C / 32 F. Mine has a manual override switch to turn it on and bypass the thermostat. I forgot about it once and it was something like -8 F the next day. WAY colder than freezing. It seemed to survive just fine, although I wouldn't want to test that theory again.

On draw down the plate will be 5 to 10 deg lower than the set point for the eutetic fluid.

Our freezer U bank melts internally at 0F and holds the freezer at 5F for 3 days.

It must be kept at -8F or so for 2 hours , every 3rd day to operate.

As the box is a combined box fridge and freezer, we have to remove some veggies to an Igloo to keep them from freezing during the 2 hour plate re-freeze.

What type of icemaker do you have and what size. *This is an addition that I contemplate for Slo Poke.*

I haven't seen this alternative mentioned, and if it has been, I'm sorry for the repetition. *We installed a Frigoboat keel cooled unit in a 13 cu. ft. refrig/freezer, and it used very little power. *In fact, 2 85 watt solar panels kept the fridge and freezer going for a week at anchor. *because water is about 35 times more efficient at cooling than air, the unit was very efficient. *It consisted of three elements, an evaporation plate, a Danfoss BD 50 and a 5" by 3" keel unit that looked like a sintered plate used for grounding. *We installed it ourselves, and were highly pleased with its performance while aboard for about a year on the intracoastal. *Cost, $1600. *The evaporator was placed in the freezer compartment, and there was a fan that blew the cold air into the fridge section. *We kept three months worth of meat frozen, and has three levels of cold in the fridge. *One for milk and such, a middle section for beer, and a top shelf for salad veggies.

Wow--lots of ideas and lots of good answers. But here is another question.

My little 31-foot trawler spent years hosting liveaboards under previous ownership and never left the dock. When whatever original refrigeration failed (it was at least two-way, as there are both 120VAC and 12VDC refrigeration switches on the panel) , somebody took it out and shoved an office-size refrigerator/freezer there that only runs on 120VAC. So my two options, it seems to me, is to install an adequate inverter and continue to run the existing refrigerator/freezer or remove this beast and install a proper two- or three-way refrigerator (I am not currently interested in a freezer).

Option A seems a good one: even if I later put in a proper two- or three-way refrigerator, I still have 120VAC available for other uses. In the long run I will remove this beast, but for now I think the hot ticket (no pun intended) is the inverter installation.

Thoughts?

-- Edited by Chris491 on Sunday 29th of August 2010 10:39:54 AM

Chris491 wrote:" somebody took it out and shoved an office-size refrigerator/freezer there that only runs on 120VAC.

Option A seems a good one: even if I later put in a proper two- or three-way refrigerator, I still have 120VAC available for other uses. In the long run I will remove this beast, but for now I think the hot ticket (no pun intended) is the inverter installation."

Click to expand...

That's exactly what happened on my boat as received from the PO. At first I thought it was a big mistake but since my boat came with a 3000 watt inverter I have found that running with the inverter on keeps evrything available to me. Refrigerator, ice maker, TV, 110 outlets, etc. I wouldn't change it.



*

Walt,

How do you handle the drain on the Ice Maker?

JD:

There is no drain on the B195 U-Line. When I need to defrost, I just fold* a towel and place it under the empty ice bucket. Turn the ice maker off and leave the door open. Takes about 1.5 hours.*** U Line Origin Series BI-95B-00 14'' Ice Maker with 12 Lbs. of Ice Storage, 23 Lbs. Daily Ice Production & No Drain Required: Black

Also, I do the same thing with my Kenmore refrigerator. (also, no drain required.) These small refrigerators from Sears (110v) only cost $100-200. They work great, consume very little power and years later, if they fail, throw them over the side and go back to Sears.

My brother who has about 30,000 miles under the keel of his 57 DeFever has been doing this for about 30 years. He buys the small freezers, puts a doily on top and uses them for an end table in the salon.

I use Thumb Locks to hold them in place. Never had one come loose.
Thumb Lock - Marine and RV West Marine sells them. Make sure that they are oriented before pressing them on as they are a real bitch to get off.




-- Edited by SeaHorse II on Sunday 29th of August 2010 06:54:58 PM

Thanks Walt.

So all you did was add a fresh water line to it.* Correct.

The question is always batt cap vs desired endurance.

For overnite any inverter and cheap chop chop inverter will usually do OK.

Want to spend 3 days on the hook with no noisemaker its far more expensive.

The "best" for the no noisemaker crowd seems to be the custom box , top loading , 4 in insulation on fridge 6 on freezer , eutetic plate and operated by a Danfloss DC unit .

Ant computer speed controlled unit will do, air cooled is preferred if the boat will be occupied while ashore at refit time.Water cooled is not much more efficient in terms of electric use or run time , compared to a PROPERLY installed air unit.

Folks with room and the bucks can simply install a Sun Frost , which looks conventional, had great insulation and is DC operated , if desired.

Usually 2 -75W solar panels will run a good well insulated box , with a smart DC system.

JD wrote:Thanks Walt.
So all you did was add a fresh water line to it.* Correct.

Click to expand...

Correct! (And plugged it in to a 110 outlet)* The 110 outlet right behind the TV.


*


-- Edited by SeaHorse II on Monday 30th of August 2010 10:55:40 AM

I know it's an old thread, but there is no way to safely install a propane refrigerator on a boat.* Stove or oven, yes.* Refrigerator or water heater, no way.

ABYC is pretty specific on propane appliances, installation, and use.* Among other things, you do not want an unattended flame on a boat.

rwidman wrote:

but there is no way to safely install a propane refrigerator on a boat.*

Click to expand...

All the canal boats in the UK (don't know about the Continent but they're probably the same) have propane water heaters and some of them have propane refrigerators.* All meeting the safety requirements of the various authorities that cover this sort of thing over there.* All the narrowboats we've hired over the years had propane hot water heaters (the first one had a propane on-demand hot water heater as well as a propane refrigerator.* Most of the boats have gone to DC refrigerators but the hot water heaters are all propane.* These boats do not use shorepower of any kind (no marinas to plug into, anyway) so they have to be self-sufficient.

*