Thread: Jet propulsion

Originally Posted by cjbfisher

I recently read an old Woodenboat magazine which featured a Lobster boat that was powered by a jet ski engine/jet drive. It got me thinking because I want to build an 18 foot (5.5m) sportfishing centre console, but my shed is only 6m deep and only just fits my 15 foot boat with outboard ( I had to cut about 100mm off the drawbar).
So I figured that if I had a jet drive, and a swing-away drawbar on the trailer, I could probably still fit it in the shed. The trailer would be no worries, as there are a few manufacturers that offer that option.
What are everyones thoughts/experiences with putting jet drives into wooden boats?
Cheers,
Chris

I have not done it, but i have seen a plan for a boat using the jet propulsion from a jet ski. Check out Glen-L for the plan.

Jet drives, like all decisions in yacht design, have their share of compromises to live with. The biggest is output. A 25 HP jet will not provide the same level of performance as a 25 HP outboard. Jets tend to be more expensive to setup, repair and operate then outboards and take up a chunk of cockpit real-estate too. On the other hand, they offer great shoal water operation options, just not available to outboards.

There aren't many plans for jet powered craft, just because they're more costly compared to I/O's and outboards, but there are some. Most all designs with any drive arrangement can accept a jet, so a retro fit on an existing design is possible.

Your question is like asking who likes Macintosh computers. Eveyone knows they are better, their sofware is superior yet everyone buys chop-shop made computers.

Jet drive are a compromise like propeller is a compromise, and unless you want to compare a jet drive with a variable pitch propeller I rather have a jet drive than a set of 4 different props a diving suit and a floating wrench.

Jet drive is big in N Z, and when earlier models had about 5% power loss compared with prop, with modern jet this is no longer the case. Price is a consideration but to compare you must compare apples with apples. If you say that a Nanni engine with a Chineese gearbox and a second hand prop is cheaper than a Steyr diesel / Hamilton HJ241 you are probably right.

As for overall lenght, remember you will still have a nozzle that sticks out the transom.

http://72.14.235.132/search?q=cache:...&hl=en&ct=clnk

http://www.scribd.com/doc/2531591/Je...loat-With-This

http://webbjet.www9.50megs.com/RJplans1.htm

http://www.glen-l.com/jetski/jetjon-index.html
http://www.glen-l.com/jetski/jetjon-notes.html

[ame="http://www.youtube.com/watch?v=xnJI0cKLh5E"]YouTube - home made jet boat[/ame]

http://www.akmining.com/boat/jetboats.htm

http://www.roguejet.com/history.asp