Why no Residential Fridges?

[svlamorocha]

Originally Posted by valhalla360

That's what I said. I abreiviated cubic centimeter to cc.

And yes, the standard for parts is to call out the displacement but the average new car buyer could care less about the displacement. They care about HP.

But to take your example a 307 sounds like a bigger number than a 185.

There is a good reason for the parts business to use the displacement. There are many different versions of an engine (each with its own HP figure) with the same displacement and share many parts (block, pistons, water pump, etc). You name the displacement and that identifies most of the parts of the engine.

There is a good reason for the people who buy/drive to the cars to use the HP figure. Power tells you how much weight the thing can pull up a certain slope, what speed can you reach with a certain cross section and Cx, how fast can it accelerate for a given weight, etc.

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[newhaul]

Originally Posted by svlamorocha

There is a good reason for the parts business to use the displacement. There are many different versions of an engine (each with its own HP figure) with the same displacement and share many parts (block, pistons, water pump, etc). You name the displacement and that identifies most of the parts of the engine.

There is a good reason for the people who buy/drive to the cars to use the HP figure. Power tells you how much weight the thing can pull up a certain slope, what speed can you reach with a certain cross section and Cx, how fast can it accelerate for a given weight, etc.

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The only issue I have is that horsepower of an engine has little to do with power. Torque is what does the work I guarantee I can pull more with a 27 horse yanmar in a tractor than I can with a 250 horse engine in a chev camaro HP= speed. Torque = power

[leftbrainstuff]

Originally Posted by nebster

Hey all,

I'm a total newbie, starting the research for living aboard a few years from now.

My family's been living in an RV for the past year, and so I have become well-acquainted with the systems we have. I am now trying to translate my understanding into things more appropriate for at sea.

The first thing I can't figure out is, why are there no residential fridges in boats? RVs basically moved to these a couple years ago, I suppose in part because they are so efficient now and in part because the Norcolds and Dometics of the world were so notoriously sucky. (And because with induction and microwave convection cooking, one can get rid of propane entirely and make things a lot simpler.)

So... is it just a space issue? Could it be something with orientation/motion? Or maybe rust and corrosion?

Thanks for clueing me. And be gentle, first post.

Space and efficiency.

The logical place for a fridge and freezer in most monohulls is not a nice large rectangular space. Some of the larger and newer monohulls, and many cats, will take a standard fridge.

Our keel cooled frigoboat fridge and freezer use a magnitude less power than a cheap 'land' fridge. They run direct off of our 12v house bank which is recharged from solar.

We now dont use our 2000W inverter except for intermittent ac loads. Microwave, bar mix and toaster. Lots of inefficiencies in ac to dc and dc to dc conversion. I believe 50%ish of household power consumption is now attributed to ac to dc converters.

Propane is a key part of our off grid solution. 2 x 20lb gas bottles last us 6 months. Induction cooking electrical loads would require a larger battery bank and solar array. We do a lot of slow cooking, baking and pressure cooker meals. Gas is more practical than electrical in our case.

Most land fridges dont meet our requirements for build quality, maintenance and parts availability.

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[svlamorocha]

Originally Posted by newhaul

The only issue I have is that horsepower of an engine has little to do with power. Torque is what does the work I guarantee I can pull more with a 27 horse yanmar in a tractor than I can with a 250 horse engine in a chev camaro HP= speed. Torque = power

You confuse "power" with "torque" with "pulling power".

Power is measured in kW or HP, torque in Nm and pulling power in N.

The difference between engine torque and power is engine rpm. The difference between torque and pulling power is how many metrs does the car displace with a turn of the engine, which in turn is determined by transmission ratio (gearbox plus differential) and all-in wheel diamater.

I give up. Whatever was not learned in high school physics cannot be made up in a sailing forum.

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[a64pilot]

I'd tell you HP and torque are inseparable, matter of fact I'd also tell you that if you look on a dyno chart you'll see that hp and torque cross over, at 5252 RPM, wonder why?

Yes I had the installed accessories and exhaust backwards, but HP is such an almost non standard term, it's almost as bad as "pretty"

[Cadence]

Originally Posted by newhaul

The only issue I have is that horsepower of an engine has little to do with power. Torque is what does the work I guarantee I can pull more with a 27 horse yanmar in a tractor than I can with a 250 horse engine in a chev camaro HP= speed. Torque = power

I was tempted to make that comparison. A Camaro wouldn't pull a sick whore of a piss pot and a small tractor will. However it is a measure of work per time period. What is it? 550lbs up one foot in one second.
don't quote me. I just read that, from a prior post. My feeble mind recalls something in the order of 750#1 ft. in one minute So I guess it is whether you want speed or usable power for work?

[leftbrainstuff]

Originally Posted by svlamorocha

You confuse "power" with "torque" with "pulling power".

Power is measured in kW or HP, torque in Nm and pulling power in N.

The difference between engine torque and power is engine rpm. The difference between torque and pulling power is how many metrs does the car displace with a turn of the engine, which in turn is determined by transmission ratio (gearbox plus differential) and all-in wheel diamater.

I give up. Whatever was not learned in high school physics cannot be made up in a sailing forum.

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I assume by pulling power you mean work. (the engineering term force x distance)

Power figures are easily inflated on tests. Rotational inertia can be used to unload and fudge power figures.

Torque is a more useful measure. For dc motors max torque is available at 0 rpm. Not so with IC engines.

Torque wins motor races. Horsepower wins pub arguments.

I dont trust the figures unless I see the plots suitably labelled.

You need to compare current inrush with electric motors. A high starting current will trip many inverters. Many domestic appliances may not play well with inverters.

Others have posted on issues in adapting domestic induction stoves to use with inverters. Worth reading up on some of those experiences before you commit yourself.

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[newhaul]

OK I will state what I assumed ppl would understand without explaining torque is stated by engine manufacturers as ft pounds of force

[newhaul]

Originally Posted by Cadence

I was tempted to make that comparison. A Camaro wouldn't put a sick whore of a piss pot and a small tractor will. However it is a measure of work per time period. What is it? 550lbs up one foot in one second.
don't quote me. So I guess it is whether you want speed or usable power for work?

I just made that comparison because the numbers were what I could think of off the top of my head. From my wrenching days on cars.

[TeddyDiver]

Originally Posted by leftbrainstuff

Our keel cooled frigoboat fridge and freezer use a magnitude less power than a cheap 'land' fridge.

While it's seems to be common way to compare $fourdigits marine fridges to the cheapest domestic ones, may I remind that there are $fourdigits domestic fridges that besides being as economical as their marin counter parts are also much smarter and can place a cherry on top of your sundowner

Still enjoying the discussion Carry on!

[Steve_C]

Torque is a measure of rotational force measured in relationship of Weight to Distance ie - ft/lbs ( or Newton/Meters) whereas Horsepower (Power in General) is the measure of total power expended.

A very high horsepower engine with low torque is inefficient where a low horsepower engine with high torque is considered highly efficient.

Just my understanding if it helps anyone. Not an "expert opinion" by any means.

As for the original question. I have seen some of the large Lagoon Cats (see attachment) with full size residential style Refers in them. Personally I would avoid at all costs as I would think they would;

1 - Dump to much heat into the cabin.
2 - Lose too much cold air every time they are opened
3 - present challenges to securing them for rough seas - Both the actual unit AND the doors.
4 - Total weight for what you get is not ideal. (Cat)
5 - No matter how efficient I would prefer NOT to have to deal with running it thru an inverter and add to the inefficiency, complexity, and vulnerability of the total setup.

Again just my humble opinion.

[Stu Jackson]

Originally Posted by sailorchic34

I am in awe. .................................................. .....................................

1 ampere hour is 2.232x10^22 electrons or 6.2 x 10^18 electrons per second for one hour. What else can it be. It's not magic or smoke and mirrors.

Pretty simple. If one removes the words between the highlighted words above, with an = sign, then, story over.

This is NOT a difficult dimensional analysis.

[sailorchic34]

Originally Posted by valhalla360

But GPH is a measure of how fast it fills up not how much it can hold.

How much does a GPH weigh?

A single GPH if it's cold water weights 8.33 pounds

[sailorchic34]

Originally Posted by Rock-Head

Some helluva thread drift. WTF does all this technical electro mumbo jumbo back n forth have to do with why there's no residential fridges in boats? :?:

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I actually do have a residential fridge on my sailboat. Others have them too.

[sailorchic34]

Originally Posted by MVDarlin

Not approved for boat use, serious hazard potential.

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I use a residential fridge with an inverter that basically acts as an isolated power supply. Its quite safe. Many dare I say most ships have 120, 480V fridges.

I'm also using a non-marine laptop, though it has a spill proof keyboard.