Jet Propelled power 1

[boatboy]

I have an Australian designed 21foot half cabin fibreglass cruiser called a 'Savage Marlin' that is nearing completion & I have purchased a used 'Noen' jet with an 8inch impeller diameter which will be driven by a small block V8 350 chev engine. What advantages & disadvantages will I be running into?

 

[truck]

Jets tend to be a little indeterminate at low speed as the aggressiveness of output is a flow volume function. This can be a little problematic if you are working in an area with relatively stout currents (e.g., docking perpendicular to the flow in a river) where the physical space constraints prevent the throttle required to adjust position; an excellent answer to this is the addition (at a fairly substantial cost) of bow or/and stern thrusters.

If you can find one, the Hinckley picnic boat uses jets and thrusters with a joystick control and can literally walk sideways; I am told that bayliner has added a jet/joystick option to one of their boats.

Having replaced my fair share of props, I like the concept of a jet, but the low speed considerations can be overwhelming depending on where you boat.

 

[truck]

Forgot on the first posting to tell you that there is an Australian manufacturer of jet drives who markets as a Hamilton; they have an excellent engineering/installation guide which would be worth procuring. Truck

 

[dieselchief]

Jet drives can be temperamental, and need to maintain close clearances to perform well. Too much clearance between the impeller and tunnel will cause cavition. Sand can be a problem, causing wear. Make sure parts are available. I am in the process of replacing 3 P-Jet units do to corrosion around the stainless steel sleeve in the tunnel causing the sleeve to go out of round.