Electric PWC

[Blusky]

Hello, I would like to develop a project of a jet ski driven by batteries, electric PWC.

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? I think that fast water jet propulsion systems is the major limitation for this Power.

Any other recomendation, comment or advice is very appreciated.

Thank you very much.

 

[Coastiejoe]

First concern I would have is the weight of the power plant. Generally speaking they are considerably heavier then a traditional engine.

Immediate second concern is how to keep it charged. With cars this is done when coasting and braking. Boats don't coast,,,

Large ships use wind mills to keep up the power or an external generator.

 

[richardpr]

The weight in batteries would be stupidly exaggerated

 

[Sportster-2001-951C-Stock]

Yes, what kind of battery do you intend on using? A craft such as you describe, would perhaps benefit greatly by using a displacement hull as opposed to a planing hull.

There must be some kind of stealth race in progress to pass boats off as PWC's, as if maybe nobody will notice? Boats are large and heavy as well.

 

[Blusky]

Hi, I think that the most important to start the design is to contact with pump and impeller manufacturers, in order to establish the power that is necessary for the electric motor, and so, to dimension the battery stacks. They could provide me more information about the power I would need, to optimize the design.

If I would propose a power of 35 kW, the pump manufacturer have to said me if it is enough, to achieve enough speed and power. Do you think is right?

 

[bigJake]

it's already been done so you don't have to reinvent the wheel. start by investigating what is already out there.

http://www.youtube.com/watch?v=6wK_R7ynkJU

 

[Blusky]

 Hi, I think that the most important is to think in the electric motor, its rpm, and so, to see what is the most optimal impeller.

On the other hand, probably it is interesting to installa a propeller in the PWC. I have not previous reference of a PWC with a propeller, do you know a model?

Thanks for your comments!

 

[Dr Honda]

We've talked about it here several times... and it's... well... a dumb project. (no disrespect)


The issues are:

1) Unlike an electric car... an electric boat needs all 50hp to maintain speed. The car, uses 50 HP to get up to speed, and then only needs 5~10 HP to maintain 60 mph. Because of that... the consumption is lower.


2) The weight of a 50hp motor, and the batteries to support it will COMPLETELY out weigh a fuel powered system.

3) Because of the weigh... you will need a bigger hull. In turn, adding weight, and reducing speed.

4) A jet pump is a HP HOG !!!! If you want to try this... you will be better off starting with a prop. You will burn less power at cruise.



And finally... a 50 hp ski won't achieve the speeds you are looking for. I would think... with it's weight... at best, you will be seeing 25~30 mph. And with the power usage... I would say, you can do that for 15 min or less. (and that's with good/expensive LiPo batteries)



I don't like to put a negative twist on anyone's experiments... but boats are power hungry, and you need a system that can be fed properly. But, good luck on the project.

 

[Blusky]

Dr Honda, thanks for your comment. It is true the challenge is quite high. Also, it is necessary an infraestructure to recharge batteries.

On the other hand, I think to improve efficiency to install a propeller. I have tryed to find previous references, but I am afraid that PWC with propeller are more dangerous and it could have problems, for example, when people would arrive to the beach, for example. So, probably it is not so interesting this option.

 

[Murph_13]

If you go forward with this project you may want to investigate cooling of your battery stacks. I've always wondered if and when electric powered boats/PWC would be developed. Always thought it would be dangerous to have a PWC that has the torque of an electric motor and no engine sound to make others on the water aware of the craft approaching...

Good luck!

 

[Sportster-2001-951C-Stock]

Since power in Watts is current in amps multiplied by volts and since my boat has a 100kW engine in it and assuming a 24volt power system the current requirement in Amps would need to be 100k/24 is 4,166 Amps, gonna need some big locomotive cable for that much current!

I don't know what can be done about the weight involved, perhaps filling the hull with helium might help some?

 

[69boss]

Just read an article about electric aircraft. Not drones but a people hauler. Basically they have the same issues with energy storage, weight, and recharge time, ect. Companies investigating have much deeper pockets than most of us. It currently isn't even close to feasible. There has to be some kind of breakthrough with batteries or solar panels.