Your best bet will be 2 motors (1 per shaft) and 1 speed control. With the prop separation being what it is, there just isn't enough leverage to effectively turn this boat by controlling the motors independently.

By all means, don't use anything more than a 385-400 size motor and certainly don't use a high power version. After all, you want time in the water, don't you? And I'll assume you aren't looking to build something capable of going scale supersonic, right?

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