RE: Need help with motors and ESC for a big boat
There are a few options available, brushed motor relatively small say 700 geared down about 10:1( a recycled cordless drill works well ) or large low speed motor such as a blower motor from a car.
The another option is a brushless setup, a very low Kv motor direct drive.
all of these options are going to have approximately the same runtime for X rpm of the prop, the slower the prop speed the lower the current(higher runtime).
Do you know the size of the prop you are going to use? this will help in getting a better idea of setups.
Nick