prop shaft

[howard69]

Had to straighten a bent prop shaft on my Howard. I got it within 15 thousands. Does anyone know if this is straight enough. I dont want to put it back in and find out its not.

[Costello]

I'd reccomend buying a new one. If it's an Aquamet shaft, the material has "memory" to flex, twist, bend, etc. and then return to it's normal state. Any bends beyond that in my mind tell me it's spent. In addition, think of a driveshaft on your car..... it's balanced!!! Same deal with your propshaft, being straight is akin to being balanced. If it's bent it will probably have noticeable harmonics and wear out strut bushings prematurely at a minimum. Tom at Menkens at the top of the page can sell you a new one of proper length. Personally, that is just not an area of the boat that I want to be frugal with.

[howard69]

I dont know what type of shaft it is,as far as I know its the original 1969. I was under the understanding they could be straightened safely.
Originally posted by Costello:
I'd reccomend buying a new one. If it's an Aquamet shaft, the material has "memory" to flex, twist, bend, etc. and then return to it's normal state. Any bends beyond that in my mind tell me it's spent. In addition, think of a driveshaft on your car..... it's balanced!!! Same deal with your propshaft, being straight is akin to being balanced. If it's bent it will probably have noticeable harmonics and wear out strut bushings prematurely at a minimum. Tom at Menkens at the top of the page can sell you a new one of proper length. Personally, that is just not an area of the boat that I want to be frugal with.

[PGF545]

Replace the shaft.....don't try to mess with it as you will only start pulling your hair out. We had Tom Bently build us one earlier this year and he does excellent work. We replace ours about every two seasons and have never broke one.

[Stab-n-Steer]

H69,
I agree with the others and I would replace the shaft. The "memory" that Costello mentions relates to the ultimate strength of the material. Anytime metal is bent to a point that it does not return to it's original shape it goes beyond it's "yield point" which permantely compromises the ultimate strength. When you bend it back it yields again weaking it even further... Have you ever taken a piece of thin sheet metal and bent it in one direction and then bent it back and forth until it breaks? With every bend it gets easier and easier to bend it in the other direction until it finally breaks. Metal fatique over time will lower the ultimate strength of your shaft. If it's been in the boat 30 years I'm sure that has had an effect...
[This message has been edited by Stab-n-Steer (edited December 18, 2001).]

[howard69]

Thanks to all for your post. I'm definately going to replace it.

[pgf127rt]

Howard69, Good decision, the prop and shaft are the 2 major factors that can cause problems and much damage to your boat and your body.