T-Pain Is On A Boat: Re: [Electric Boats] Re: Emerging technology

Friday, November 6, 2009

Re: [Electric Boats] Re: Emerging technology - hopefully lower cost

In the never ending saga of the Florida Manatee, I have over the years seen all kinds of "solutions" proposed and none ever being actually used. From electric table fan type wire enclosures around the boat's propeller all the way up to the circular band around the outside of the propeller like the website 'marinejet" proposes. The drag and extra fuel consumption these added on devices generate virtually guarantees nobody will use them. The "jetski" type propulsion really works to protect the manatees but is difficult to maintain for a boat residing "in the water" all of its time. Mega-yachts do use the water-jet principle effectively to achieve truly impressive speeds but have "doors" that close off the jet tunnel and a flushing system when it is not in use to prevent fouling. On smaller boats this is wildly complicated and not cost effective. Also add in the engineering reports that Kort-type nozzles loose any advantages it has over conventional propellers as the boat speed increases. That is why they are used on tug boats and other slow moving vessels requiring power (traction) and not speed.

--- On Fri, 11/6/09, danbollinger <no_reply@yahoogroups.com> wrote:

From: danbollinger <no_reply@yahoogroups.com>
Subject: [Electric Boats] Re: Emerging technology - hopefully lower cost
To: electricboats@yahoogroups.com
Date: Friday, November 6, 2009, 8:18 AM

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, "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.marineje t.com/view/ 67
>
>
>
> I'll be keeping my eye on it.
>
>
>
> Kevin
>