Help on prop and shaft size/ placement

[adams3287]

I am needing some guidance on my prop and shaft position on my '64 Islander 32'. This boat has been an 8 year project that has revcently been left to me by my late father. The new shaft that had been purchased and installed passes through a composite cutlass bearing assemble before exiting the rear of the keel. Un fortunately the shaft is so short that the propeller butts up against the keel with only maybe an 1/8" clearance. My feeling is that the shaft should be about 2" longer which would place the prop safely away from the keel and fairly centered in the area between the modified full keel and the clamshell rudder. This would also give me additional clearance in a larger prop should ever be required, currently there may be a 1/4-1/2" between the top of the blade and bottom of the hull that goes over the propellor area because of its current close proximity to the keel.

Any direction and recommendations are greatly appreciated.

Fair winds and following seas!!

TJ

[Gene T]

Do you have room inside to add a flexible coupling. That would set the shaft back a bit.
R andDDrivesaver at WestMarineNew

Gene

[captbillc]

i don't know what you mean by a clamshell rudder. i am assuming it is not cutaway for the prop. i believe the clearance recommended between the prop & the hull is about 20% of the radius of the propellor. too close will cause vibration. you will get better steering under power if the prop is fairly close the the rudder.

[adams3287]

Originally Posted by captbillc

i don't know what you mean by a clamshell rudder. i am assuming it is not cutaway for the prop. i believe the clearance recommended between the prop & the hull is about 20% of the radius of the propellor. too close will cause vibration. you will get better steering under power if the prop is fairly close the the rudder.

There is a cutaway for the prop, the rudder is hinged to the rear of the keel as many of these old keels were. I agree that the spacing is less than adequate and have pretty well talked myself into finding a new shaft today.

Gene, I dont believe I have that kind of space, the engine in the boat was an aftermarket addition and somewhat larger than the original atomic four it was originally launched with.