RotoBoat?
 

Just thinking creative off-the-wall stuff here, and I know that the rotary engine has received at least one certification for use in an aircraft, so why not?

It would seem possible to power a boat with a rotary engine, enjoying the same advantages the powerplant offers in a sports car, namely very compact size and light weight.

The problems might be the high operating temperature -- specifically the need for a water-cooled exhaust -- and, I suppose, our little fuel consumption issue. I don't know about the matter of a marine transmission and propellor at 9,000 RPM. :lol:

Any thoughts?

http://seabreacher.com/seabreacher-x

atkins rotary also had a marine division. but the site seems to be down

http://www.youtube.com/watch?v=jk1qFaaq4q4

http://www.youtube.com/watch?v=AzRmYud0HR4

http://www.youtube.com/watch?v=dOp9CsE2HMY

http://www.youtube.com/watch?v=nQv9N...eature=related

bottom line is, its been done

This is a 12 rotor engine for a drag boat

http://www.smith-power.com/yahoo_sit...0207_large.jpg

the Xboard powered surfboard

http://fastcache.gawkerassets.com/as..._jet_board.jpg

is powered by a 40 hp 400cc rotary. the board is capable of 45 mph

https://www.rx8club.com/attachment.p...1&d=1315690766

How about a rotary powered air plane? That would be awesome.

Here are two to try:

http://www.rotaryeng.net/

http://www.americanrotaryengine.com/

how about the more inclusive "aircraft"

http://www.flightglobal.com/assets/g...x?ItemID=23146

http://www.eetasia.com/ARTICLES/2007...1_CTRLD_NT.jpg

http://www.militaryfactory.com/aircr...-450-uav_2.jpg

http://www.jedsite.info/elgg1.2/pg/g...1285954971.jpg

http://www.aero-news.net/images/cont...E-POD-0707.JPG

http://images.ookaboo.com/photo/s/Cypher_UAV_s.jpg

I meant commercial plane...

Here's a link to a boating forum thread with discussion of rotary-powered boats, aircraft, motorcycles, jet skis, and lawnmowers:

http://www.boatdesign.net/forums/diy...ine-23824.html

That seabreacher is badass but did anyone else notice the water getting inside the cabin when it submerged.

There was a 16' 13B jet boat that was made about 8 yrs ago. I believe it was produced in TN.
The problem with a rotary in a boat is it's high RPM. It will cause the propeller (or impeller in a jet boat) to cavitate unless you use some sort of reduction. Boat's with gasoline piston engines run at about 2500 - 3000 RPM max. Diesel engines about half that.
Fuel consumption is high on a boat due to it's contact with the water. I had a 36' cruiser with twin Chrysler big blocks that were almost 300 hp each. It got around 1 (one) MPG at cruising speed. It had two 80 gal fuel tanks. Marine gas was priced at 25% higher than what you buy for the car. And car gas has road fuel taxes added.