Yep, much of the promotional hype can be misleading. Let's figure that they're using the Tesla type batteries and for 100 pounds, they get 4kWh usable. If their claim that their highly efficient pod pumps will drive the boat at 65mph with only 24hp is true, that is quite an accomplishment. But the math is still kind of wonky. 1hp = 750 watts so 24hp = 18000 watts, so it looks like about 12 minutes of maximum power would drain the 4,000 watts of usable battery. Alternatively, stretching the batteries out to 3 hours means that the average draw is 1333 watts or around 1 3/4 hp. That is certainly not high speed action in any way you can look at it. However, both of their claims can be technically true, the boat may be able to hit 65mph and one could operate it for 3 hours on a single charge.
This is not the first company to use this type of factual, yet easily misinterpreted, claim. A more accurate way to market electric drives is max speed of xxx and max duration (or range) of xxx at xxx speed. Unfortunately, that kind of detailed disclosure is rare, even in places like this (you should see some of the owners/builders claims on the DIY Electric Car board).
I do believe that the Silviera Group's ultra light weight PWC has reduced their HP requirements to 1/10 of a conventional 240-260hp jet ski, they are hitting 65mph with 65hp or about 4 to 1 efficiency increase while still using gas power. Throw in the ICE to electric conversion and 10 to 1 seems doable. So perhaps your performance with 90hp on a conventional jet ski (45mph top speed) could translate to 10hp on a Samba-like boat. Suddenly the 100 pound 4kWh pack can drive your for more than 30 minutes at full throttle. Of course, this is a very broad extrapolation of the limited data given; I'd believe it more with some proof of concept results. But it does serve as a good example of the potential opportunities of improving the efficiency of the boat and not just the drive.
So all you electric sailboat owners should keep your bottoms clean, it can make a difference... :)
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Rob McAfee <rob_mcafee@...> wrote:
>
> Eric,
>
> That's a good way of looking at it... I would definitely want the running
> capacity of 3 gallons of gas or more, since the tank currently holds a little
> over 4 gallons. I'll put this idea on the back burner until battery tech
> improves. :)
>
> Now I'm puzzled about the Samba specs. They claim the entire boat weighs only
> 200 lbs, but you're saying the battery pack itself would weigh that much. It
> doesn't add up... I won't be getting my hopes up for the Samba either!
>
> Rob
>
>
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