Found some old footage of our 8'4 Power Boards motorised surfboard from 7 years ago. We have altered our fin drive system since then to make it more efficient. Speed has never been an issue using the one drive system. Speed can be varied by a simple change of the voltage, the propellers (from 3 blade to 5 blade with various pitch and diameter) or by a simple change of motor specification to suit whatever product the fin system may be adapted to.