GG, I stand corrected on the current (amperage) issue. Thanks.
I don't have a 'very fast boat', I actually have a tug but I have been making my own propellers - nice, shiny, brass ones are not available to buy here, in Taiwan - and have been getting curious about their effect on shaft speed.
For instance, I have a 65mm dia, rather coarse pitch jobby that pushes the boat very well. I also have an 80mm dia, fine pitch prop. that pushes the same boat very well, but the latter sends up something of a rooster-tail at full power.
Now, if the smaller one is trying to push a small column of water very fast (coarse pitch) and the larger one is trying to push a much larger (80^2 * PI/4 vs. 65^2 * Pi/4) column at a slower speed due to its finer pitch, which one allows the motor to turn nearer to its optimum speed? I want to measure it.
Proteus, I have written to the Spektrumrc site you offered, it could be just what I'm looking for. Thanks.
Geoff