Correction, 8S is not the same as 4S2P. The former is 29.6 volts, the latter is just 14.8 volts. They require completely different motors. You want 8S for your boat, 8S1P for less weight, 8S2P for longer run times (and twice the cost).

You want an inrunner motor, the “open frame” motors are outrunners. The former are much easier to cool, in years past a few 1/8 scale racers used outrunners, but today I’d use inrunners. A 40mm x 100 mm motor will work well with the ~850 Kv. I use OSE a lot, the owner supports hobbyists and racers.

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