Keel Cooling - Page 4 - RC Groups
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Aug 01, 2009, 01:22 PM
Registered User
CornelP's Avatar
Well, I somehow don't think he actually did the radiators because he needed them, more like to see if it can be done...
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Aug 01, 2009, 02:56 PM
USA'd ex Brit
toesup's Avatar
Originally Posted by green-boat
Consider this:

Some of the ponds I run my boat in, the summer time temp of the water is considerably hotter at the surface. It would almost seem counter productive to water cool the electronics with hot water. If you are generating that much heat then you need to get a bigger ESC or a more efficient motor.
Even with warm water in the pond, the insides of the boat and the electronics (ESC and Motor) are more than likely to be hotter than the surrounding water, especially if the boat is working hard 'on the pull'.

Even though a pair of 40amp ESC's and either Pittman's or Graupner 900's might not get that warm...

Originally Posted by CornelP
Well, I somehow don't think he actually did the radiators because he needed them, more like to see if it can be done
Aug 01, 2009, 03:19 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Originally Posted by CornelP
Well, I somehow don't think he actually did the radiators because he needed them, more like to see if it can be done...
You can actually by small radiators, but they can be awfully expensive.

More fun to make your own, and you get bragging rights.
Aug 02, 2009, 02:52 AM
Crazy Dallas
i agree with you Kmot, maybe a clear coat or just auto body wax(saw it in a old furniture store i worked in for brass/copper outdoor items).. let your skills shine!
also, if you want them functional, the least amount of coating means the most efficient water to water cooling.
Last edited by jdcanadian; Aug 02, 2009 at 02:54 AM. Reason: cont...
Aug 02, 2009, 04:02 AM
Registered User
CornelP's Avatar
Toes, if you really want to test this to its full potential, take a look at
article: Plating copper onto coins using available chemicals and supplies
Tried and tested by a friend of mine, the results are very nice. Being a mild solution you do not have to care about the solder part, it will get covered as well, it just takes longer...
Aug 03, 2009, 12:31 PM
Registered User
“What color would heat exchangers be on a submersible at 3000' depth where there is no visible light? ”

Out of curiosity I’d like to know…. but I think the fact that its freezing down there would preclude the use of coolers as the case would do it? The space shuttle polished coolers was an interesting fact. I have also read/heard that for the best heat transfer without any special ceramic type coatings would be painted black.
Aug 03, 2009, 01:43 PM
Cadmunkey's Avatar
OK, I've been reading this thread and want to stick in my two cents. Color of the keel cooler does not matter. We are talking about a fluid heat exchange. The heat is transferred from one body of water into the cooler material and then into the other body of water. The transfer occurs when molecules of different temperature come into contact with each other and transfer excess heat energy from the warmer on to the colder one.

Light is Energy.

The color of the object doesn't even affect air to air transfer what it affects is the amount of energy that is absorbed from the suns radiation(light). Color is based on pigments they absorb different colors of light and reflect back others to give an object a color. So, you start of with a beam of light traveling at an object. That beam is white and has all the colors (ROYGBIV) in it. Lets say the object is blue. The light travels at the object and when the light hits it all the colors except the blue are absorbed and the some blue is reflected back at the eye. The darker the color the more light is absorbed the lighter the color the more light is reflected. A white object reflects most of the light while a black object absorbs most of the light.

Energy cannot be created or destroyed only transferred.

Any light that is absorbed by the pigment is energy and must be transferred into something else and therefore it gets turned into heat. Apply this to the space shuttle, they make the coolers chrome so that as much light and radiation is reflected as possible, therefore the suns rays cannot heat the cooler up, it is only in contact with the nothingness of space and therefore cools.

A test for those with no lives or nothing better to do. Take two pieces of similar metals. Paint one flat black and the other flat white. Put them outside for a while about 6" apart in the sun on a hot day. Guaranteed the black one will become hotter than the white one. Then stick them in a pool about at least 2' under water for a while, and they will have the exact same temperature. Radiation from the sun and heat transfer from the air is quite negligible compared to the high efficiency of heat transfer in water.

So for the coolers on Toes's tug, paint or finish them whatever color you want this is a physical transfer of heat from one molecule touching another. What will affect its ability to transfer heat is the thickness of the metal and the finish. If you want it to work its best leave it as metal. Metal will conduct heat better than almost any another material out there. Any finish will act as a heat barrier, but we are talking a coat or two of paint so it wont be much.

Hopefully that makes sense.

It amazing how what you learn in thermodynamics class can apply to model boat so often.

Last edited by Cadmunkey; Aug 03, 2009 at 01:48 PM.
Aug 07, 2009, 09:25 PM
USA'd ex Brit
toesup's Avatar
Originally Posted by Ghost 2501
novel idea, complete with header tank as well?
Shaun and I discussed the layout of the equipment over lunch (thanks Shaun!) and came to the conclusion that the best (for cooling) layout would be from the header tank, to the pump, to the keel coolers, to the ESC, to the motors and back in to the header tank.
That way the coolest liquid, from the coolers always hits the ESC first...

That raised an interesting question about the header tank and how it might get warm as the water entering it would have just come through the ESC and motor...

Having looked at the proposed header tanks i was going to use, a pair of RC Nitro car tanks, i decided that they wouldn't do the job... and set about designing a specially made header tank..

Over the last couple of days i have produced this... Ali header tank, finned.. and with a cooling fan (just in case).. It still needs some more work..
Aug 07, 2009, 09:46 PM
Registered User
Hee hee!
Aug 07, 2009, 11:12 PM
Grumpa Tom
Kmot's Avatar
That's pretty sweet!
Aug 08, 2009, 06:19 PM
USA'd ex Brit
toesup's Avatar
I've just run an experiment...

I put the keel cooler in a bowl of iced water and pumped about 1/2 pint of hot water through the cooler...

The water (in the bowl) i was continually pumping through the cooler went from hot, from the faucet, to cold in about 8 minutes..

I think i have a working system..
Aug 09, 2009, 04:57 AM
Boaters are nice people.
Hi Toes,

Does this mean you'll need a pond with iced water to run your boat in, in future?

Just kidding...

Very nice work on the cooling sysyem!

Regards, Jan.
Aug 09, 2009, 08:03 AM
Registered User
CornelP's Avatar
Jan has a point... are you trying to make an ice breaker?
Aug 09, 2009, 07:04 PM
Is it supposed to do that...?
For what its worth I've seen many "old-school" keel coolers, heat exchangers, or whatever you want to call them under tugs, fishboats, powerboats, you name it, my Dad worked at a small shipyard and we saw lots of approaches.
What I remember was that the cooling ability of a system was measured in terms of the surface area of the tubes your coolant ran through. More surface area = more cooling. Some of the fancier setups used finned tubes, where the fins were cast into the tube, ran the length of the tube and were quite robust. In most cases the tubesets were few, long and of relatively small OD, rather than many shorter tubes. I always thought this was for less drag but? We never painted the tubes but they always did have at least one zinc. I've enjoyed reading this thread, thanks.
Aug 10, 2009, 12:53 PM
3 Blades to the Wind
Shaun Hendricks's Avatar
That is one sweet header tank Toes. It's even better than I was picturing it when we were talking about it!

I had another bizzare thought just strike me, what if you built it like a 'boiler' for a steam system but instead of passing heated air through the flues, pass cold air driven by the fan... exhaust it straight up and out a funnel... maybe with a smoker putting in some added effect. A very mild smoke might look downright modern from an environmentally friendly scrubber system.

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