Firstly, I am new to this site and reside in Australia. My adult son has rekindled my interest in boating and has convinced me that fast electrics are the way to go. He has a Zonda which has been clocked with GPS at the magic 160 kph, however, my direction is not to achieve a speed anywhere near this. I would be happy with around 60 kph.

Now my question. A friend recently gave me an old 70 cm shallow vee mono hull that had been set up with a brushed 540 motor, although this has been lost years ago. The drive ran through a reduction gearbox with a ratio of 0.734. The design is not surface drive and has the conventional drive through a 3 mm shaft with a basic 37 mm plastic propellor. As the shaft is firmly bonded to the shell I am reluctant to remove and replace with a 4 mm shaft. Thus the 3 mm shaft plus the reduction drive will be limiting factors.

The hull design is quite sleek so I do not think the hull design will be a problem. I have started to reinforce the shell by filleting the inside join with epoxy.

Now to the drive. Personally, I would prefer a 35 amp 540 size Leopard brushless inrunner to enable easy install to the existing mounting, however, my speed enthused son thinks that a 65 amp Leopard would be better. The ESC would be a 120 amp model, with both the motor and ESC water cooled. Turn fins and trim tabs will be fitted. A 35 mm two-blade CNC propellor is planned.

Any thoughts please, Tim