The rotation of the motor has a significant
effect on which way the boat drifts.

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Don't you mean the rotation of the motor (and therefore a LH or RH prop)has a
significant effect on the way the boat backs?

90% of the time a "drifitng" boat will be idling. Never heard that there's
enough torque transmistted through the stringers to "significantly" effect a
drifitng boat.