Any Jet Boat experts on the forum ?

[scottrods]

ok. I work for HamiltonJet and recently helped a friend rebuild a single stage Colorado with a Ford V6. Forget what brand is spinning the jet.

Your basic problem will be that the single stage Colorado is only good enough for about 100bhp. Even the coarsest single impellor is only capable of running without a lot of cavitation up to 130bhp. Here are some links to the user manual.

http://www.hamjet.co.nz/includes/fil...s%20Manual.pdf

http://www.hamjet.co.nz/includes/fil...s%20Manual.pdf

Page 4 in this one gives you impellor info versus bhp.

http://www.hamjet.co.nz/includes/fil...al%20Guide.pdf


It cavitates simply because you're spinning the impellor too quick to push water and the boat. The impellor is digging a hole in the water - it isn't pushing it. A bit like having 500bhp with the wrong differential and 10inch wheels on a car. Some options - make the jet a multiple stage, try a coarser impellor, change the engine to less BHP or just don't jump on the gas so much and let it take time to get on the plane.

Lightening the boat will change affect the planing speed but won't help with getting on the plane if the impellor doesn't match the bhp.

Plenty of good information over on the nzjetboating forum. nzjetboating.com Web Board. - Index

Jonathan