Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: jaymac on July 31, 2014, 07:34:03 pm
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Would it be likely that motors would not run as hot running free in pond as opposed running static in the bath
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Shouldn't make a difference unless the model has ventilation.
Ned
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Aaargh was hoping it would :} have to see if I c n find some kinda heat sinks water cooling is a nono
Thanks
Jay
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:-)) Get yourself a computer fan from Maplins, mount it behind motor will keep motor cool, runs on 6v OK,another point is your prop to big or shaft out of line with motor,usually something simple try these first before buying fan,had this problem with a second hand boat found that shaft was full of grease that had gone solid,let me know how you get on,Ray. :-))
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In an enclosed volume like the inside of a boat, if cooling is needed, the important thing is to move the heat out of the boat. A heatsink and/or a fan helps the motor transfer heat from itself to its surroundings, but if its an enclosed box, the surroundings get hot as well.
If the motor is big enough for the boat and if not being forced to labour by having a stiff prop shaft or too much prop it shouldn't get too hot anyway. Generally speaking, with motors, "too hot" means "pain on touching".
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Well if you do not use very cheap plastic props, the motor will draw much more amps during static running in the bathroom.
I just recently saw a motor going up in smoke during extended bollard pull tests, which was never getting above 30°C under normal running conditions.
Expect the amps to be at least 30% more like 50-100% higher during bollard pull tests, which should be the same as static running in the bathroom.
Its mainly depending on the prop stiffness, number of blades or square surface of the blades. The higher, the higher the amps during bollard pull tests compared to free running.
Btw. the heat dissipation through GRP hulls is extremely high.
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:-)) I agree with Malcolmfrary,I would check all the other points before going down the water cooling road,a lot of modern motors are quite happy running very warm as long as you don't burn your fingers you are OK,I have used the fan method on a couple of models which did not have any windows in, I had a Vernon police boat with a 1950s Mills special 1.3cc diesel which was not water cooled, I used 3" computer fan on that and that motor is still going strong!,Ray. :-)) :-)) :-)) :-))
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I forgot that the 100% more amps only count for brushed motors.
Brushless are much worse since they donīt loose so much rpm under load. The amps drawn can be 5 times higher than free running.
But anyways.
A motor in a boat travelling less than 10 mph that needs cooling is either to small or has to much rpm.
The key is too adjust prop size and pitch + motor rpm to the speed you want to run.
If you can tell more about the model (type, weight, length), motors props... maybe we find a better solution.
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Thanks to all for the input my main question was really as to whether there was any difference. Heat I can work around afraid propshafts to me either turn or they dont I cant make any difference
Time Bandit its a 1/35 S-Boot and I have just changed from 2x385 motors (too slow) to 2x380's as advised (debatable whether any faster) on this mornings trial props are 2x3 blade brass 25mm
all upweight a couple packs of fags :}