About the amps drawn by 500 types motors:

Depending on the load these motors can easily draw 6 Ah, starting up can peak to 20 Ah.

An extreme example is my mono1, powered by a 600 race, driving a 37,5K surfacedrive on 7cells (GP3300), the runtime is just over 8 minutes, making a average of 24 Ah !

Don't underestimate these little Amp eaters, they have poor efficiency, sometimes as low as 65%, combined with the losses on the cables and drive train, they are in fact not the best way to make your boat go.

But hey, there cheap!

That's why manufacturers use them in RTR boats, a halfway decent motor would make the offer less attractive.

Greetings, Jan.