Have to agree again with Dave. Nimh's would better and be less weight for the motor to drag along. the lead/acids will be too much dead weight, Ive been there myself with a Perkasa, thought ue to their capacity, but their weight negated the advantage and the boat hardly moved above a brisk walking speed.

hI Brian
Sounding good. if I recall correctly Component Shop were selling 12v NiMh batteries on their stand at the last show I attended, so you may be able to keep the weight down and not exceed the recommended max voltage. Just had a quick look and indeed they do, from about A£24.
Good luck

Hi,Dave,
Thanks for the comments.
I researched and bought an "Electronize" FR15HVR-AN speed controller from the extremely helpful guys in Sutton Coldfield.

The boat is weighing in at about 10lbs all up, and running a 45mm prop.

The ESC comes with some neat features, such as adjustable speed range, variable frequency range, and preset neutral, and I will be starting off very cautiously, I'll probably turn the throttle speed trim down after set up, and tape it there!!

And if all else fails, I can invest in two slightly heavier 6 volt lead/acid batteries.

I may not make Chasewater this weekend after all, but maybe the one after.
Thanks again for the help.

Brian.

HI Brian
Look at http://www.produktinfo.conrad.com/datenblaetter/200000-224999/222377-an-01-en-E_Motor_Torpedo_850.pdf. This gives some specs for the 850. 😊
The Important bit is the max advisable amps at max (recommended) voltage. in this case 13 amps x 12 volts = 156 watts. This is the motor rating and if overloded it will heat up to destruction. 😓
So if you wish to use on 14.4 volts the max current you can allow is 156/14 = 11.1 amps.
To achieve this you will have to choose a suitable prop that loads the motor to less than this maximum, or you can fit a reduction unit to the motor to allow for a larger prop.
There are Wattmeter units available to help you check your setup, perhaps someone at Chasewater has one and can help you. 😀
The stall current is 40amps so you will need a suitable ESC and fuse to protect your model.
Good luck with you efforts.

Thanks, Gregg!
I will go ahead and try it with a couple of older NiCad packs I have as a trial, and if I can get it going tomorrow or Friday, I may drag myself over to Chasewater to try it out.

Brian.

Kindly remember that the motor would only get maximum volts on full throttle, as the voltage varies with the speed, so at slow speed, the esc may only be pushing , say 4-6 volts, half speed its on 9 volts, etc. So you should be ok. but what you really need is a couple of Lipo 7.4v batteries, as they are so, so much lighter than nicads or other "sticks" and give you a better amperage output too., so for example, get a 7.4v lipo, 5000mahr 20 or 25c rated. you should not need a 30c rated, as these are a bit more expensive. The "C" rating by the way [if you are not aware] is the rating given to lipos for their "output capacity" in so much as "how fast it will it let the power out" so to speak.

Providing you make sure the motor gets sufficient cooling, be it by motor driven fan or water cooling coil, it should be ok. Dont forget to NOT drive it flat out all the time on the pool [ha ha].