Anyone hear of RipJet?

[Beausoleil]

I found a couple articles thru Google News referring to a company in Tallahassee, FL that has invented a electric marine "jet" drive. From EVWorld:

"Inventor Professor Hugh Nicholson, working in conjunction with Boston University, discovered new physical properties of water that separates a water and vapor stream within the drive and pushes out significantly greater thrust than it takes in. Independent tests from the University of Michigan’s Hydrodynamics Lab reports that a 15 lb. electric RipJet® can create a comparable thrust to a 175 lb. conventional gas motor."

Hmm, perhaps I may be able to install a bow thruster after all!

[Dockhead]

If you believe the materials on their site (http://www.ripjetdrive.com/index.php), it is a highly efficient jet drive, which is more efficient than regular propellers.

This phrase, however: " Inventor Hugh Nicholson found that the jet separates a water and vapor stream within the drive and pushes out significantly greater thrust than it takes in."

seems like patent nonsense to me. A propeller or jet drive doesn't "take in" thrust. It takes power from some kind of engine, and converts this to thrust. The efficiency of this conversion is what is at stake. If this device is really as efficient as it is claimed to be, then it could be a very significant development -- we might someday be giving up our propellers, and we might have much better outboards, and not just electric ones. IF the claims are true -- we'll see.

[GordMay]

"New" physical properties of water - wow!
More output than input - wow, free energy!
Nobel prize - FOR CERTAIN!!!

[Dockhead]

Originally Posted by GordMay

"New" physical properties of water - wow!
More output than input - wow, free energy!
Nobel prize - FOR CERTAIN!!!

The company is rather loose with words which imply a perpetual motion machine -- a very bad sign of the company's seriousness.

But if you read the data, the message is somewhat different.

It's not "thrust", which is put out in greater volumes than goes in (which is absurd). It's volume. That's because the device apparently creates water vapor on purpose, and this comes out the back of the machine to together with impelled water, so increasing the volume of the fluids coming out, compared to the plain seawater going in. Supposedly this creates a kind of ram-jet effect. Well, it could be.

If you look at the independent test they published, assuming it's not fake, the device represents an incremental improvement on efficient propellers -- maybe 20% better. The improvement over jet drives like those used in jet skis is much greater. This is not exactly a revolution, but if the tests are not fake, and if the device is practical in other aspects, then it might be something good for us.

But again, the hype is quite off-putting and makes me quite cautious.

[category4jay]

if it sounds too good to be true......

[James S]

I can see from the pictures that its a rim driven prop with an open center...this has been done in the past by several company's working on a quieter, more efficient, and less prone to fowling....this is one of many examples Van der Velden ® Marine Systems rudders manoeuvring systems steering gear

One of the things that seems to be different is the shape of the blades.
I can believe that this design would be more efficient at moving water than a conventional prop of certainly more efficient than a jet ski type propulsion system.
That's about as far as I can see....and I like it.

[avb3]

Originally Posted by Dockhead

...

But again, the hype is quite off-putting and makes me quite cautious.

Not to hijack a thread, but I think sailors have become more and more skeptical of products that live on hype, such as Rocna, detailed in this thread.

Claims must not only appear to be credible, they must stand the test of credibility.

If not, perhaps the products hocked are best done so in the "As Seen on TV" section in your local discount store.