Max
Unfortunately, for what you want to do, this is not a suitable motor despite its price being right.
The motor is a 600 size motor (36mm diam.) and would only be sized to run on 6-8 cells. The brushes are non-replaceable so once you wear them out the motor is junk. The particular wind of this motor (its nominal voltage rating) is 14.4 v. or in other words 12 cells. If you check the Johnson performance specs for this motor on 14.4 volts and under load (as it would be running in a boat) you will see that it turns in the neighborhood of 11000 rpm. This is much too low for a hydroplane. In a hydroplane (rigger) and using a surface drive you will need the motor to run direct drive (no gears) and ideally you want the motor to turn underload somewhere over 20000 rpm. For this particular motor to turn at that rpm, you would have to apply probably over 20 volts. In a rigger sized to carry that kind of weight, that motor on that kind of voltage would be toast in a few minutes.