Input on PWC powerplant as aux. power for sailboat.

[LP]

There are the obvious cautions to worry about with concern for the use of gasoline as with all gas powered boats.

It's probably just a hairbrained idea that won't leave the grey matter.

Aside from the gas issues, are there efficiency issues? Reliability issues?

Initial thinking makes me think that the jet propulsion system could be faired into the hull rather readily. It would eliminate prop drag when not in use. The power systems appear to be quite proven, though not neccessarily in this application. The components are readily available. I can just imagine the shallow draft capabilities.

But holy smokes! I just went to the SeaDoo web sight to check on HP ratings. 130HP on the two models I looked. I was figuring something in the 25-50 HP range. Do all PWC have such overgrown powerplants?

I figured in an aux. application, it could be run in the 25-50% power range and get 8-12 HP, at 130 HP, the efficiencies are just going to terrible.


I'm open for comments.

[jim lee]

How are you planning on solving the entire "reverse" issue running a built in jetpump?

-jim lee

[catsketcher]

Jet drives were tried on multihulls in the early 70s by Lock Crowther. They were removed because they do not work as auxiliaries.

An auxiliary is meant to move a boat slowly. It is more efficient to move twice as much water half the speed. Fast boats need to move water quickly - like Jet skis so their propulsion system will be geared to high speeds rather than low speed efficiency.

Always try to spin the biggest prop you can for motoring slowly but then the prop should be removed when sailing. This is why many cats have outboards - you can have a big prop that lifts up when you sail.

Not only will the jet ski motor be noisy and thirsty it will be very bad karma - a piece of jet ski on a sailing boat - sounds like going to the dark side.

cheers

Phil

[LP]

This is one of those "what if" discussions.

In all reality, if this idea made sense, it would probably been done already. I haven't really considered reverse. Some kind of calmshell device, similar to a kitchen rudder. More of a thrust reverser than a rudder. Now we are adding complexity to the equation, but maybe not so complex as a reversing gear.

My original line of thinking was that with the multitude of PWC's around, cost and availability might make it a viable auxillary power unit. I appreciate your interest.

Unfortunately, there has been a definite lack of interest in the idea and that may be an answer in itself.

Phil,
Thanks for the response. I didn't see your response until after writing the above. I understand your concern about bad karma. Anything that takes a PWC out of commission is good though right? A little dark side is OK. Your response makes total sense so that will help me to move on and deal with the phen shui issues in my latest design.

Happy sailing.