There's been a commercial running down here in florida (I dunno about elsewhere) that advertises a 2-seater turbo 4 stroke powered watercraft... and then it suddenly hit me!

A rotary watercraft! Wouldn't that be cool? I don't have the money or the knowledge to do it, but I figured I'd throw it out there so someone else can try.

 

I know they've been used in boat racing before, going up against big-block V8's and the like. One thing that's extremely important in boat racing is weight. The lower a boat sits in the water (ie: the more wetted area of the hull that's in contact with the water), the more horsepower required to overcome it.
Big V8's are HEAVY. Rotaries aren't, but can be made to produce comparable hp to the V8, without compromising durability (at least by racing standards), and without increasing weight by any substantial amount. During these races, low-end torque is not an issue as it would be in drag racing.
This means that even a less-powerful rotary can compete very well against V8-powered boats due to the reduced wetted area of the hull.

 

http://www.atkinsrotary.com/Klem.htm

Found lots others, just search "rotary engine boats", I use Google.

 

A peripheral port engine would be perfect in a boat.

 

My brother-in-law was at an auction about a year ago where they sold a little miniature boat hull that was powered by a small rotary engine. The thing had a long pole attached to it for the purpose of pulling a person on skis who holds on to the pole and controls the speed and direction. It sold for $500, wish I'd been there to see it!

 

http://www.rexxracing.com/

 

i wish there was a way to fit a pp 13b into a jetski, not a bad i dea for sure

 

There is a boat in Melbourne down here running a 20b with (IIRC) a TA51 ... sounds awesome

 

not bad at all..

 

about three years back there was a thread going on about a rotary jet ski cant remember where it was posted . had some pics too

 

its a tight fit, and with PP i'm not sure how beefy to make the drivertrain to the jet. i would be looking at 300-350 hp... i can't get it low enough to line up, will have to have a gearset.

 

* this is not my ad or engine* a new fully marinised 13b!
but for someone interested, i think this seems like an excellent deal mostly because the seller claims it as 'new from factory' and for only $6500(probably will take offers too) you can't go wrong
Rotary Marine Engine / Transmission Shaft drive