----- Original Message -----From: danbollingerSent: Saturday, November 07, 2009 5:44 PMSubject: [Electric Boats] Re: Emerging technology - hopefully lower costYeh, I saw they called it a jet drive, but then they can call it anything they like. :) I checked out their website before posting.
I have driven/repaired a jet drive boat and worked on a project with Goulds pumps where I learned impeller basics.
Here is a picture of a Berkely jet drive impeller. They've been around a long time, too. You'll notice they don't look anything like the propellers Marine Drive is using in their project.
http://www.berkeleyjet.com/images/ 150-L-05660. jpg
--- In electricboats@yahoogroups. , "Alycia & Kevin Miller-Lynch" <ak@...> wrote:com
>
> If you read the website they clearly state that it is a jet, and their goal
> is higher speed, not efficiency. Seeing as these folks have been in
> business for quite a while and build a variety of jets (check out the rest
> of the site), I'll argue they know a little bit about what they are doing..
> I'll keeping tuned to see what they come up with.
>
>
>
> Kevin
>
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>
>
> From: electricboats@yahoogroups. [mailto:electricboats@com yahoogroups. ]com
> On Behalf Of danbollinger
> Sent: Friday, November 06, 2009 8:19 AM
> To: electricboats@yahoogroups. com
> Subject: [Electric Boats] Re: Emerging technology - hopefully lower cost
>
>
>
>
>
> The website doesn't call it a Kort Nozzle, which is good, because it ain't!
> Kort nozzels have an airfoil-like cross section and the exhaust opens up in
> diameter, not restricts like this does.
>
> What this unit is doing is creating a semi-jet system. It isn't a true jet
> because they are using a truncated propeller (which a Kort nozzle uses, too)
> and not an axial impeller that true jet systems use.
>
> I would be surprised if this works. They are creating the jet exhause (high
> speed exhaust) under water. The friction between water to water is great and
> causes a lot of power-robbing turbulence. There is a reason jet systems
> exhaust above the water line. One under water jet system injects air all
> around the nozzle exit to help with this friction. And, it is going to be a
> fouling nightmare.
>
> Torqeedo has the right idea. Spin a larger prop slower for more efficiency.
>
> --- In electricboats@yahoogroups. com
> <mailto:electricboats%40yahoogroups .com> , "Alycia & Kevin Miller-Lynch"
> <ak@> wrote:
> >
> > I'm interested in small (12-18ft) electric boats for fishing, play etc,
> and
> > like the cost of trolling motors. I saw this today which is an interesting
> > improvement on the trolling motor concept.
> >
> > http://www.marinejet.com/view/ 67
> >
> >
> >
> > I'll be keeping my eye on it.
> >
> >
> >
> > Kevin
> >
>
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