newbie needing help

[featherfanatic]

I have recently purchased a 40 hp short shaft tiller motor. The guy I bought it from said it was a long shaft and I didn't notice he was wrong. I put it on my boat which is a tall transom. It cavitates some but I still get good speed out of it and it pees plenty of water. Looks like the cav plate is inch or two from the keel. My question is if I buy or build a plate to set it back say 3 inches where it will get cleaner water will that fix my cavitation problem? The boat will run 33 mph now so the motor is close tto where it needs to be. I really don't want to cut the transom and don't have 500 bucks to spend on to make it a 20 in shaft. The boat is a 16 ft all welded grizzly btw

Any thoughts?

Thanks

 

[Pas Bon]

Re: newbie needing help

Setting your motor back allows you to raise it so I would assume it would help it

 

[steelespike]

Re: newbie needing help

You may be right but its highly unlikely it would perform anywhere normal if it was a short shaft
that would raise the prop 5" blades would comepletely break the surface.More than likely what you have is a slightly taller 20" transom combinded with a slightly short 20" motor.
There was a brand new boat on here w 20" transom and a new I think suzuki long shaft motor.
They had venting pronblems with anything but straight line running. The boat company soon revealed they had built the transom too tall and offered a number of solutions one of which was
a jack plate. Yes a setback should solve your problem If you build it like a jack plate you could fine tune the height for best performance.

 

[will941s]

Re: newbie needing help

Mine has a 20" transome...with a little 1-1 1/2 lip on the top of it where the fiberglass was pressed back together after they covered the transome material. So I guess you could say I have a 21 1/2" transome. I could just cut it down....but; the motor cavatation plate is like 1" about the keel, and it performs like a dream. The boat is a 14 1/2' BayRayder made by Bay Craft which made a little recessed ledge in the back, which in turn helps clean water reach the motor, much like a jackplate would do. Never had a problem with it. If you are having cavatation problems in turns or when hitting rough water, by all means just get a jackplate or set the motor back a few inches.....it helps.