Electric PWC

[BluSky]

Hello, I would like to develop a project of a jet ski driven by batteries, electric PWC. Dimensions of such PWC are: 3,40x1,25x1,20 meters.

The typical power of a PWC is about 150 hp (112 kW). The problem I find mainly is to achieve this power to the limitation of space, weight and flotation and stability problems, and mainly budget. I also want to set as the design basis a speed of 70-90 km/h (40-50 knots).

So I'm considering reducing power about 35 kW (50 hp). Therefore:
Do you think that would be enough power?

For reaching targets marked, can be redefined impeller or propeller design, with the same power of 35 kW to reach this speed?

Any other recomendation, comment or advice is very appreciated.

Thank you very much.

[Hydra]

Welcome to CruisersForum, BluSky
This is a forum about cruising. Then, not many people here are interested in PWC. I am not... I am just a marine engineer.

For a rough power estimate, you could consider that engine power is proportional to speed^3*weight^(2/3). Then, if you divide the power by 3 and keep the same weight, you reduce the speed by the third root of 3 (1.4422): instead of 50kts, you get 35kts. Of course, the weight includes the driver and any passengers.

I don't think it would be possible to get a massive increase in waterjet efficiency.

If my computations are correct, going from a 230kg (total weight) / 112kW / 50kts PWC to a 35kW / 40kts one is possible only if the total weight (hull+engine+battery+waterjet+driver) is kept under 110kg. Not likely.

Alain

[BluSky]

Thanks Hydra for your comments. I hope to be a marine engineer one day. This is the reason why I want to develop the project.