Today I was testing the motor-kayak B450 with the transom elevated for 10 cm. Additional board could be set inside the boat (for the air-propeller engine) and outside it – for the regular outboard motor.
The elevated transom is better for the air-engine Kolibri than a regular one. The speed was up to 10 km/hour by GPS.
After removing the elevated transom, I was testing a new propeller with 9 cm pitch for my 5 HP Mercury outboard. With this boat this propeller does not work well – the hull on the speed is not stable. The regular propeller (8 cm pitch) is working much better.
The same 5 HP outboard set on the elevated transom is working fine; the propeller is not “sucking” the air. I have elevated the outboard for one more inch – everything is working fine. The boat with a payload (including a driver) about 140 kg is moving up to 22 km/h.
So, a regular outboard on this boat could be set up to 12-13 cm higher. In this case only the lower part of the propeller will be sticking below the boat contour. This will sufficiently decrease the minimum depth where the boat could be going.