Hi Stuart,
If brushless is an option, take a look at the motorisation in my M.A.S. build:
http://www.modelboatmayhem.co.uk/forum/index.php/topic,34033.0.htmlThe setup is much lighter than the brushed motor I originally had planned.
As you can see in the running pics, I have more than enough power, running on 4S.
Should that prove too fast for your liking, run on 3S, much more scale like (but less fun...!).
Frankly, a brushed motor in a 40" hull isn't the best solution, unless you go for a fan motor as my original idea was.
This fan motor will turn the prop easily.
The 800 and 900 motors are rather inefficient (up to 30% of your power is lost, transferred into heat) and require watercooling.
Gears are very noisy in general.
The twin 600 motor on a single shaft is an outdated concept from the times cheap motors had to propell too large boats on a budget...
Do you have some pictures of your build, please?
I checked the type youre building, it's a stepped hull!
This requires a lightweight build in order to run as the original, meaning no heavy NiMH and brushed motors, at least in my book...
Check out the running pics in my thread.
Regards, Jan.