You're going to need two speed controllers. If you have a 3 or more channel radio, I would plug the ESC's into seperate channels, then mix them. That way you can trim the motors at top end so they run at the same RPM. They should be fairly close out of the box, but variations in propelles, motors, etc could make them run at different speed. If you have only a 2 channel radio, then you'll need a "Y" harness. You'll just have to trim out any differences with the ruddder.

Depending on your setup, you could run one battery or two. One would be my suggestion, that way you don't have any problems with one motor/esc combo running down before the other.

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