SeaDoo impellor as tunnel hull prop

any oppinions
having trouble finding a prop of the right diamiter
and this impellor beginning to look very good

 

Impellers are made to operate in a chamber with fairly tight fit. They don't work as propellers.

 

It could possibly work... but be prepared if it doesn't.
Several years ago (before Jet Ski s) I worked with a fellow who developed a 7' long remote control water ski tug (Ski Skipper) powered by a snowmobile engine. A propeller was not available so he used an impeller from a water-jet mounted in a full tunnel -top and 2 sides - like a jet with no bottom. It managed to launch a 200# man in a wet suit and tow around at about 25 mph. But, the whole project was dumped when new laws came in requiring an observer on the towing boat.
That said, this was a prototype and the 'fit' was not the best. I guess my friend got lucky.
Years later I worked with another company developing an autonomous, air dropped rescue boat. This was essentially a self-propelled life raft which could re-position itself so speed was not important - 4-6 knots was fine. Again, we used the tunnel but with a large blade prop. Things were moving along quite well and then 9/11 came along and the project got dropped.