Very cool boat Damon.
I had to look up how long a competition slalom course is, it's about 850' or close to 1/6 of a mile. Given their stats of 28 runs on a single charge, that's about 4.6 miles at about 30kts. That doesn't include the other slower speed running while setting up or going back to the beginning of the course (I don't know if they ran the course both ways)
The other number that they give is 4.5 hours to recharge from 220VAC at 50A (or somewhere in that range). If we assume 10kW of charging, they could be using as much as 45kWh on a sigle charge. Alternatively, they say that a full charge casts about $3.00. I looked up Florida electric rates and they seem to be close to what I pay in Los Angeles, about $0.12/kWh. That works out to 25kWh for the full charge.
Going back to the slalom course. each run times out at about 40 seconds, but should include acceleration time too. So I would say that 28 runs would be about 30 minutes at full throttle. For the sake of our conversation, I'll say that 20kWh of the charge goes to the full throttle runs. If that is true, then the twin motors are pulling about 40kW. I would say that the range is about 90 minutes with 30 minutes of full throttle and an hour at about 5kW (displacement mode). Staying in displacement mode, the abatteries should last 5 hours.
The motors appear to be like the AC motors used in EV conversions, but they might be more high tech, I think that the drive provider has connections with big auto manufacturer vendors. Looking at what I could buy from conversion vendors, twin AC-20s would combine to 90hp and 220 ft/lbs of torque. Each motor could easily take the 20kW load, at 96V that's just over 200A. Considering that the regular Nautique ski boats come with 300-400hp ICE, this might be about right. Nautique chose a straight drive shaft with a PSS shaft seal rather than an outdrive.
The empty weight on the Nautique ski boats seems to start around 3000 lbs, not bad for a 20' power boat.
If I were to put one of these together, I would buy 750-800 lbs of LiFePO4 batteries (25kWh usable) - $14,000, and the twin AC-20 motors - about $7000, throw in $3000 for cabling, charger, drive connection and reduction. And the conversion should be around $25,000 after you buy the boat. I don't know if my version would perform as well as their boat, but it should end up fairly close. Without real specs from Nautique, my specs are just guesses, but it all seems reasonable. And the total weight will still be within the manufacturer's stated capacity.
Anyway, that's my quick analysis.
Fair winds and smooth seas,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "damonalane" <damon.andrew.lane@...> wrote:
>
> Jerry, there's an all-electric ski boat prototype that has been built and can do 28 ski runs before recharging (not sure what that is in miles or hours). I don't know if you'd be able to find the technical details on it, and they probably spent many tens of thousands on this proof of concept, but it can be done. There is plenty online about the electric Nautique.
>
> http://www.boatingmag.com/engines/alternate%20propulsion/amazing-electric-ski-boat
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> >
> > With a loaded daisplacement of 3500lbs, you're going to be hard pressed to provide enough power to get the boat to plane. With their small engine option being 135hp, I would say that you'll need a motor close to 50hp/38kW (maybe more) to achieve reasonable performance. Even with LiFePO4 batteries, 1000lbs ($18,000) will probably only give you 60 minutes of normal operation. You won't be able to pull a skier.
> >
> > Using the existing outdrive may also be an issue, I've heard of previous attempts to do so, and the outdrive absorbed a significant amount of the motors's output. Your outdrive might be better, I don't know if the outdrive manufacturers or anyone else has efficiency specs for those units.
> >
> > Limit your self to slow speeds like your Electrocraft and the project becomes more reasonable.
> >
> > Eric
> > 1964 Cheoy Lee Bemuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh LiFePO4 batteries.
> > Marina del Rey, CA
> >
> > --- In electricboats@yahoogroups.com, "Larry" <lmills187@> wrote:
> > >
> > > I would like to convert a boat, like a Four Winns H180, to electric power. I would remove the engine and couple an electric motor to the outdrive. Has anyone attempted to convert a non displacement hull boat to electric? What size electric motor would be required to get reasonable performance? I would use LiFe04 batteries.
> > > Any thoughts, other than that I am "crazy", would be appreciated.
> > >
> > > I currently have an ElectroCraft LS14 electric boat. Since it is a displacement type hull, it is limited to slow speeds. This conversion would be to get something that provides better performance.
> > >
> > > Regards,
> > >
> > > Larry
> > >
> >
>
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