Why no Residential Fridges?

[sailorchic34]

Originally Posted by Stu Jackson

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.

Bless you, kind sir.

BTW, I'm keeping totally out of the HP discussion. I mainly use boiler horsepower (BHP) which is 34.5 pounds of steam per hour.

Oh wait..... DOH!

[Cadence]

Originally Posted by 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.

[Wotname]

Originally Posted by StuM

If you are going to quote authorities, it really helps if you provide the URL so that others can fact check!.....

Here you go
electric charge | physics | Britannica.com

I note that the same source has a differing view in the page you linked.
Suggests either sloppy writing by the source or disagreement among professionals or....

I don't have the time available to provide an argument for or against the coulomb story right now or to read following [posts , that will have to wait 12 hours or so (and another 3 pages on this thread ).

Stay tuned and enjoy the other arguments about gallons and hp and rpm and toque and maybe friges...

[Cadence]

Originally Posted by Stu Jackson

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.

Stu,

Get off the electrons and coulombs. It has no practical application.

I haven't heard coulombs since college and that was 50 yrs. ago.

This, I think, is a practical thread. I believe not a course in physics so amps work. And a google of the physics does not make you an expert.

Sorry if I sound crass. But stop with the non relevant BS.

[Rock-Head]

Originally Posted by sailorchic34

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

So do i!

Sent from my SM-N900V using Cruisers Sailing Forum mobile app

[newhaul]

The only thing I would have a problem with a residential fridge would be where would you place it on a smaller vessel. A custom built unit would have more usable space and be able to fit in with a curved hull. On my islander the only spot to realisticly place a dorm fridge is under the companoway step. I have seen them there on other IB 24's however on mine that is where I have placed my battery bank.

[sailorchic34]

Originally Posted by newhaul

The only thing I would have a problem with a residential fridge would be where would you place it on a smaller vessel. A custom built unit would have more usable space and be able to fit in with a curved hull. On my islander the only spot to realisticly place a dorm fridge is under the companoway step. I have seen them there on other IB 24's however on mine that is where I have placed my battery bank.

I mounted my fridge to the starboard salon seating adjacent to my stove. It's bolted down to the frame and to the deck behind and above it.

I attached a SS clasp to keep the door closed when healed over.

I use the old ice box as drygoods storage.

[newhaul]

Originally Posted by sailorchic34

I mounted my fridge to the starboard salon seating adjacent to my stove. It's bolted down to the frame and to the deck behind and above it.

I attached a SS clasp to keep the door closed when healed over.

I use the old ice box as drygoods storage.

My lil 24 is ten short of yours I am looking at doing a conversion of my icebox with and hold your hats for this I'm sure it will create a whole another thread drift on power and all but I'm going to use the pielter unit out of a koolatron 12 volt coo,er with 6 inches insulation and running it with a fridge type thermostat set to maintain 40 deg when I need refrigeration. And shut off when I don't . Adding 10) watts solar on push pit to power it.

[StuM]

Originally Posted by newhaul

My lil 24 is ten short of yours I am looking at doing a conversion of my icebox with and hold your hats for this I'm sure it will create a whole another thread drift on power and all but I'm going to use the pielter unit out of a koolatron 12 volt coo,er with 6 inches insulation and running it with a fridge type thermostat set to maintain 40 deg when I need refrigeration. And shut off when I don't . Adding 10) watts solar on push pit to power it.

Are you familiar with the efficiency of thermoelectric cooling compared to the alternatives? Have you done the math for the Amp hrs required to cool a single 325ml drink can from your ambient down to 40 degrees?

[Wotname]

Originally Posted by valhalla360

Interestingly, I found several sources that call an amp the fundamental unit for charge and coulumb defined by it. Including the origianl govt SI site I quoted. An official SI site would seem to have more credence than "whatis.com" in my mind.

The again, many of the fundmental units have been redefined based on atomic measurements A meter is a particular distance traveled by a photon in a period of time when originally it was intended to be 1/10,000,000 of the distance from the equator to the pole. Until they found out that earth isn't a perfect sphere, so the redefined it as a piece of metal then as they needed more accuracy, they went to the atomic based measurement.

Please explain how something can be dimensionless if it is defined by two dimensions that are not the same. Ie:
- Time/Time is dimensionless as the dimensions cancel out (anything divided by itsel is 1)
- Gal/Hr has dimensions.

Originally Posted by StuM

If you are going to quote authorities, it really helps if you provide the URL so that others can fact check!
Fact checking your sources reveals a slightly different picture to what you have represented.



That is NOT an accurate quote from Encyclopedia Britannica here:

coulomb | unit of energy measurement | Britannica.com
which actually says:

"Coulomb, unit of electric charge in the metre-kilogram-second-ampere system, the basis of the SI system of physical units. The coulomb is defined as the quantity of electricity transported in one second by a current of one ampere. Named for the 18th–19th-century French physicist Charles-Augustin de Coulomb, it is approximately equivalent to 6.24 × 1018 electrons. See electric charge."

The Definition as stated is 1 Ampere second. The actual wording of the sentence which corresponds to your highlighted section contains the word "approximately" and is therefore certainly not a definition.



Then fact checking at Whatis.com we have:
Table of Physical Units - Reference from WhatIs.com
where we find:
"charge quantity ( Q ) coulomb (C)" under the table of Derived Units.

So your first authority actually does define charge quantity as Amp seconds and your second reference, assuming your quote is correct, has two opposing definitions which suggests that it is not a very good authority.

Originally Posted by StuM

Oh, just spotted another misconception:

"The bit in red strongly suggests that a coulomb is simply a specified number of natural units - thus dimensionless."

Dimensionless doesn't mean a number of natural units. If it is defined in term of a single natural unit, then that has one dimension. A dimensionless number is just that - a bare number such as Reynold's number,specific gravity, pH or 42. It doesn't have any "dimension" or "natural unit".

How did we get back to fridges
Boring...
Now back to coulombs
But first deal with "dimensionless"
let's agree that "dozen" is a dimensionless unit - yes? We know what is means and often it is a useful way to quantity something. If we buy a dozen eggs, the unit "dozen" remains dimensionless yet we can work with a dozen eggs and use that in mathematical ways like we use a dozen eggs a day so how many do we need for the next trip on 10 days. We are talking about a dozen eggs/day; dozen remains dimensionless even though our units are now "eggs per day" or if you like "eggs/day". As an aside, our egg storage capacity might be considered in egg.days and so the egg locker might hold 10 dozen egg.days. I submit that "dozen" remains dimensionless.

Now for coulombs but allow me an analogy first. Consider our old friend the ampere, great for quantifying electrical current flow. In trade school the ampere was defined as the amount of current that would flow when 1 volt was applied to a 1 ohm resistor. So 1 volt across a load of 1 ohm produced 1 ampere of current. Quite straightforward, easily measured, easily demonstrated and easily understood (by most ). Mathematically, rather than using the unit "ampere", it could have been replaced by volt/ohm. All the various equations that use amperes will work mathematically if it is replaced with volt/ohm. So at the end of trade school, we really knew how to work out current, we just measured the volts and the resistance and hey presto, we could determine the number of amps - worked every time .

Then at uni degree level, we found out that an ampere was really defined as "The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length."
This is the same definition given in Base unit definitions: Ampere
Yet Wikipedia gives a deeper story on various definitions of the ampere, have a read here https://en.wikipedia.org/wiki/Ampere

Who is to say what an ampere is but it can easy be understood to be the equivalent current flow of 1 volt across 1 ohm. However clearly that is only a way to understand what an ampere is, it doesn't define it as such.

I suggest the ampere analogy is very similar to the coulomb story.

We didn't really learn much about coulombs in trade school, they got a mention and we were taught that is quantified "charge" and was useful to determine electrical capacity and was the equivalent of 1 ampere.second. However the only useful application was understanding battery capacity in amp.hours

Back at uni though, the coulomb got some rigorous attention and from what I recall, it was the unit for electric charge and electrical capacity. As far as electric charge went, it was a "coulombs worth" protons (+ve charge) and / or a "coulombs worth" of electrons (-ve charge). The fact that the numbers were different between the protons and the electrons use confusing (at least to me ). It was used in the same way as we used the term "dozen" and as such, the unit was dimensionless. When it was applied to quantify electrical capacity, it was described as being the equivalent of 1 ampere.second. This was useful . But it was never defined as 1 ampere.second. So the uni teaching matched what I now read in both What is coulomb? - Definition from WhatIs.com and electric charge | physics | Britannica.com.

I do note however that Britannia also seemingly contradicts itself here coulomb | unit of energy measurement | Britannica.com

I can only speculate why this is so .
Wiki is worse (IMO) https://en.wikipedia.org/wiki/Coulomb

It seems to me that when using coulomb as a way of understanding electrical capacity, it is best to use it as the equivalent of of 1 ampere.second but when using it as a way of understanding electrical charge, it is really best to think of it a very big number of the charge one would get from a lot of protons in one spot OR as a slightly different big number of electrons. In either case (protons or electrons), the number is simply reduced to a singular unit known as a coulomb in much the same way as we use the unit "dozen".

YMMV

[valhalla360]

Originally Posted by sailorchic34

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

I challenge you to provide an independent source that supports your statement.

It must be quoted in GPH and only GPH (no adding a duration or otherwise changing the units).

I'll accept any reputable source that is within 20% (to account for rounding errors)

[valhalla360]

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 are making the mistake of confusing engine HP with mechanical advantage.

Give me the right system of gears and pullies and I can drag a semi backwards when the semi driver has it in gear and the pedal mashed to the floor...but no one is going to believe for a second that I have more HP in my arms and legs than the semi does in it's engine.

Torque just determines if you can turn something. HP determines how fast you can go, assuming there is enough torque to get it turning.

With gearing, you can get wildly different torque (at the wheels) from the exact same engine and that's the basis for your tractor being able to pull stumps while the car won't be able to (there is also the issue of tractor tires having better grip on soft soil)

[valhalla360]

Originally Posted by Wotname

How did we get back to fridges
Boring...
Now back to coulombs
But first deal with "dimensionless"
let's agree that "dozen" is a dimensionless unit - yes? We know what is means and often it is a useful way to quantity something. If we buy a dozen eggs, the unit "dozen" remains dimensionless yet we can work with a dozen eggs and use that in mathematical ways like we use a dozen eggs a day so how many do we need for the next trip on 10 days. We are talking about a dozen eggs/day; dozen remains dimensionless even though our units are now "eggs per day" or if you like "eggs/day". As an aside, our egg storage capacity might be considered in egg.days and so the egg locker might hold 10 dozen egg.days. I submit that "dozen" remains dimensionless.

Now for coulombs but allow me an analogy first. Consider our old friend the ampere, great for quantifying electrical current flow. In trade school the ampere was defined as the amount of current that would flow when 1 volt was applied to a 1 ohm resistor. So 1 volt across a load of 1 ohm produced 1 ampere of current. Quite straightforward, easily measured, easily demonstrated and easily understood (by most ). Mathematically, rather than using the unit "ampere", it could have been replaced by volt/ohm. All the various equations that use amperes will work mathematically if it is replaced with volt/ohm. So at the end of trade school, we really knew how to work out current, we just measured the volts and the resistance and hey presto, we could determine the number of amps - worked every time .

Then at uni degree level, we found out that an ampere was really defined as "The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length."
This is the same definition given in Base unit definitions: Ampere
Yet Wikipedia gives a deeper story on various definitions of the ampere, have a read here https://en.wikipedia.org/wiki/Ampere

Who is to say what an ampere is but it can easy be understood to be the equivalent current flow of 1 volt across 1 ohm. However clearly that is only a way to understand what an ampere is, it doesn't define it as such.

I suggest the ampere analogy is very similar to the coulomb story.

We didn't really learn much about coulombs in trade school, they got a mention and we were taught that is quantified "charge" and was useful to determine electrical capacity and was the equivalent of 1 ampere.second. However the only useful application was understanding battery capacity in amp.hours

Back at uni though, the coulomb got some rigorous attention and from what I recall, it was the unit for electric charge and electrical capacity. As far as electric charge went, it was a "coulombs worth" protons (+ve charge) and / or a "coulombs worth" of electrons (-ve charge). The fact that the numbers were different between the protons and the electrons use confusing (at least to me ). It was used in the same way as we used the term "dozen" and as such, the unit was dimensionless. When it was applied to quantify electrical capacity, it was described as being the equivalent of 1 ampere.second. This was useful . But it was never defined as 1 ampere.second. So the uni teaching matched what I now read in both What is coulomb? - Definition from WhatIs.com and electric charge | physics | Britannica.com.

I do note however that Britannia also seemingly contradicts itself here coulomb | unit of energy measurement | Britannica.com

I can only speculate why this is so .
Wiki is worse (IMO) https://en.wikipedia.org/wiki/Coulomb

It seems to me that when using coulomb as a way of understanding electrical capacity, it is best to use it as the equivalent of of 1 ampere.second but when using it as a way of understanding electrical charge, it is really best to think of it a very big number of the charge one would get from a lot of protons in one spot OR as a slightly different big number of electrons. In either case (protons or electrons), the number is simply reduced to a singular unit known as a coulomb in much the same way as we use the unit "dozen".

YMMV

If you have a dozen eggs...the unit is "eggs".
If you are going to measure charge in terms of electrons...the unit is "electron charges" (or similarly you could use protons).

Speaking in terms of dozens is really just a bastardized combination of base 10 and base 12 numbering systems. Base 12 has some major advantages as it can evenly be divided by 6 differnt numbers. Base 10 can only be divided by 4 different numbers. The main downside is everyone is used to working in base 10. The most obvious point where we see this is in shipping and packaging. If you go to the grocery store and look at packaging, it's almost always base 12 based. (6 pack are 1/2 of 12, a case is a 24 pack which is 2 of 12, etc...)

The problem with calling it dimensionless is it can't have dimensions. Ie: if you have 10 kg/kg, kg/kg must equal 1 since anything divided by itself is by definition 1. Thus you have 10*KG/KG = 10 * 1 = 10 (no dimensions)

If 1 C = 1 amp* sec, the only way for it to be dimensionless is if 1amp = 1/(1 * sec). Thus 1 amp * sec = 1/(1 *sec) * sec = 1 * sec/sec = 1 * 1 = 1.

Since nothing in my engineer courses nor that I can find anything online suggests 1 amp = 1/(1 * sec), it can't be dimensionless, since we have it defined by dimensions.

[valhalla360]

Originally Posted by newhaul

The only thing I would have a problem with a residential fridge would be where would you place it on a smaller vessel. A custom built unit would have more usable space and be able to fit in with a curved hull. On my islander the only spot to realisticly place a dorm fridge is under the companoway step. I have seen them there on other IB 24's however on mine that is where I have placed my battery bank.

Space and staying reasonably level.

We actually bought a small residential fridge just this week. We have a small cabin on the new boat just aft of the stove that we are using as a pantry. It was a bit of a wrestling match getting it in but beats the heck out of the engine compressor driven unit that had to be run every day. And at $180, drastically cheaper than a dedicated marine unit.

We figure we will use it most of the time which is at dock with shore power available and when we anchor out, we run the engine.

[StuM]

Quote:
Originally Posted by newhaul
My lil 24 is ten short of yours I am looking at doing a conversion of my icebox with and hold your hats for this I'm sure it will create a whole another thread drift on power and all but I'm going to use the pielter unit out of a koolatron 12 volt coo,er with 6 inches insulation and running it with a fridge type thermostat set to maintain 40 deg when I need refrigeration. And shut off when I don't . Adding 10) watts solar on push pit to power it.

Are you familiar with the efficiency of thermoelectric cooling compared to the alternatives? Have you done the math for the Amp hrs required to cool a single 325ml drink can from your ambient down to 40 degrees?

Just for sh*t and giggles, I did some calcs. So to take a short digression from GPH, Coulombs, dimensions and HP/ccs - here goes another direction of thread drift:

Averag US summer temperature 75F = 24C
Safe fridge temperature 40F = 4C
So we need a 20C drop
I can = 0.33litres (approx)

To raise or lower 1 litre of water by 1C takes 1kilocalorie
and 1kcal = 1.163 Watt Hours

So to reduce 1 can by 20 degrees we need
1.163 x .33 x 20 = 7.7 Watt Hours (approx)

A 100Watt panel will generate maybe 500 Watt hours per day at best
So if the system were 100% efficient, we could cool about 13 cans from a full days output of the 100 Watt solar panel.

Unfortunately Peltier systems have about 5-8% Carnot efficiency.
(Carnot efficiency is the percentage efficiency compared to a theoretical 100% efficient heat pump.)

So it will take the full output of your 100 Watt panel all day to cool a single can.

And that's without taking into account any other draw such as cooling fans to move the heat away.