Conytrapel Propulsion

[tom kane]

http://www.marinelink.com/news/contrapels-waterline348736.aspx
Has any one had a look at this propulsion.
What are your opinions about it.

 

[Mr Efficiency]

I couldn't find a diagramatic representation of this, or visualize how it actually works.

 

[CDK]

Quote from the Contrapel web page:

"The system is so advanced that it carries out all the functions of both propellers and water-jets with none of the drawbacks of either. "

That sounds too good to be true, so it probably isn't.

 

[Mr Efficiency]

My first thought was it has to lift all the water passing through the drive, which is an immediate penalty. Pix needed.

 

[Alumination]

This video has an animated GIF at the 1:30 point.

https://www.youtube.com/watch?v=oMQmPl42c9E#t=112

 

[gonzo]

It is amusing. Pseudoscience and sales hype at its best.

 

[DCockey]

Looks like a waterjet system designed for increased efficiency at lower speed operation. From the Contrapel website:

According to Contrapel’s own on-water tests, the higher efficiency of the new system provides the following improvements compared with boats that are equipped with traditional jet drive installations:

1) Vastly improved thrust at low and mid speeds
2) Better fuel economy at low and mid speeds due to vastly improved control.
3) Highly survivable and operable in extreme conditions, including brown and black-water environments.
4) Will lower global marine carbon footprint
5) Significantly lower noise and vibration levels

Interesting that the performance advantages compared to traditional jet drives are claimed for low and mid speeds only, and that no performance comparisons to conventional prop systems are made. My understanding of the conventional wisdom is traditional, unducted props are generally more efficient at low speeds.

Perhaps someone familiar with the fundamental principals of jet drive systems will comment.

 

[whitepointer23]

Its had a lot of money put into it looking at how well engineered it is. The kiwis are experts when it comes to jet boats so maybe there claims are not far fetched. Its good to see a working eexample instead of the usual computer renderings.

 

[Mr Efficiency]

This video has an animated GIF at the 1:30 point.

https://www.youtube.com/watch?v=oMQmPl42c9E#t=112

Thanks for posting that. It does give some limited idea of the set-up. I think it is trying to squeeze a bit more efficiency out of the jet drive principle by the CR, combined with the high volume & low speed angle. Doubt it is getting close to a conventional prop set-up in mpg terms. But it has the low draft and less chance of striking obstacles, and might be attractive for heavier slower boats needing to negotiate shallows.

 

[DCockey]

In some respects the ContraPel system might be considered as an extension of a tunnel drive with the bottom of the tunnel closed under the props.

 

[Mr Efficiency]

In some respects the ContraPel system might be considered as an extension of a tunnel drive with the bottom of the tunnel closed under the props.

I was thinking something similar.

 

[Alumination]

The key points I've picked up from the videos:

Hybrid propellers, not impellers.
Low pressure high mass/volume, the opposite of a jet.

A re-optimized jet?
Enclosed propeller?

Apparently after this launches he intends to introduce an even better "oscillating" version.

The proof will be in the performance of the final product.

 

[tom kane]

A simpler version of the same principle shown in previous thread.

 

[JSL]

Looks like a mixed breed between
DuoProp + Traktor Jet, + Surface drive = Controversy, ContraCompeller
Certainly a good conversation starter

ps: I went back and read the sales literature more carefully. Some valuable information .....which is essentially BBB.

 

[sharpii2]

This looks like an expen$ive version of tunnel drive.

It is probably more efficient at low to mid speed ranges, as they say, than a jet drive, but is probably less efficient than a plain prop.

Then, with its ocillations and bounter rotations, is probably much more expensive. Plus you have the friction of the fluid going past the tunnel walls.

My guess is that in a few applications all this expense might be worth it.

I wouldn't expect to see it on the everyday runabouts though.