Electric Wave runner Help

[rotzinger]

Hello fellow boaters

Look my project is to make an electric wave runner WITHOUT sacrificing performance, I’ve already resolved the electricity problem, and my problem now is to know what size of electric motor I need to make the wave perform the same as the gas one. This is a normal Yamaha 600, I just want it to be the same as the gas one or close.

Thanks for your help guys

[marshmat]

Hi rotzinger,
Such conversions have been discussed on here before. For example:
Electric Jet Ski Conversion
Electric Waverunner?
To summarize: A few people have built electric PWCs with comparable top speed to the gas version, but the endurance/range is very limited. Read the linked threads in detail.
It's impossible to make a reasonable suggestion regarding the motor without also knowing what the power source (batteries) will be, the intended weight of the system, and the design priorities (do you want range, top speed or acceleration / low-speed fun?)

[rotzinger]

The power source I am thinking of is 10 kg =) and it will, in theory, give me 1 h 30 min in a 6 kw motor at top speed. The thing is I need to know the motor size to calculate the power output I need.

[marshmat]

1h30 @ 6 kW = 9 kW.h = 32.4 MJ, excluding losses. Better than 3.2 MJ/kg energy density.... are you fiddling around with lithium-air or nanowire batteries, rotzinger?

If you want to match the gas powered PWC's top speed, the power-to-weight ratio of the electric boat should be similar to the gas one. 6 kW = 8 hp, you'd need at least four times that (possibly a fair bit more) to get a comparable power to weight ratio. 6 kW might be enough to get it to plow around at 10 mph with its bow in the air. You might be able to find a forklift motor from which you can coax 24 kW / 32 hp, which would be enough to get the PWC moving reasonably well.

If you care more about how it accelerates and how it performs at lower speeds, you can probably get by with a lower rated motor. Anything I suggest, though, would be a wild guess without a lot more information about the boat and the already-determined aspects of the proposed conversion- especially the mystery power source. (If the numbers you provided above are real, I suggest you give one of the big carmakers a call. Show them the working prototype and you should have ten million dollars in your pocket by the time you leave the office!)

[rotzinger]

no man its not a battery source jajajaja its waay better....... hydrogen fule cell muajajajajajaja at long last you know the truth jajajajaja its all in theory and it might not even be cost worthy to get such a big fule cell. my problem is to find the correct motor an then try to get the correct fule cell. the numbers i have are from a fuel cell airplane =)

[rotzinger]

soo you think i would need 35 hp to run like gas???? i have little experience in marine stuf. my hull is an old yamaha 700 or something like that

[marshmat]

Ahh, OK then.
A one-off 24 kW mobile fuel cell using current technology is roughly $75,000 USD. There's a good chance that could be brought down to $7500 or so if/when carmakers start mass producing them.
For the moment, if you want to pour $75k into rebuilding a PWC, that's your decision. It would not be mine.

[rotzinger]

yhea thats the point jajajaja i heard you can make the cells at home i might give it a try jajajajaja

[daiquiri]

What does "jajajajaja" mean?

Almost the same as "Gadagadagadagada", which would signify a joke. It's a Mexican thing (or maybe Latin American? - I know a Venezuelan that does it too). Why wife used to do it too to signify laughing in type. It seems nervous to me.
Hombre, are you on Tequesquitengo? You'll make a fortune in rentals if you can pull it off without electrocuting yourself! Where will you get the hydrogen?

[rotzinger]

well my friend it just happens to be that ive lived all my life in mexico so i kind a use latin expresions and it also happens to be that im a Praxair dealer so y can get hydrogen realy easely. and no, im not in tequesquitengo, im in cancun.

[CatBuilder]

Originally Posted by daiquiri

What does "jajajajaja" mean?

I see people from South/Central American who have Spanish as a primary language use it in place of "Ha ha ha ha"

It signifies laughter, but it's not English. It's Spanish (of American origin, I think).

Note that in Spanish, the word Jalepeno is actually pronounced "hallapeenio" The J's take on a H sound, so you can see the connection to "ha ha ha ha"