Rudder shaft

[rognvald]

Originally Posted by Cheechako

Yeah, never been a fan of hollow shafts.

Cheechhako,
So, to awaken a sleeping dog . . . what would you use to fill a hollow shaft and why? Also, if the shaft is hollow at the bottom (inside the rudder), wouldn't moisture in the shaft eventually cause delamination of the rudder core and/or disintegration of the rudder cage?

[Adodero]

We are replacing it with a solid shaft, the weight difference is surprisingly minimal and I don't want to worry with it again.

[Cheechako]

Originally Posted by rognvald

Cheechhako,
So, to awaken a sleeping dog . . . what would you use to fill a hollow shaft and why? Also, if the shaft is hollow at the bottom (inside the rudder), wouldn't moisture in the shaft eventually cause delamination of the rudder core and/or disintegration of the rudder cage?

Personally I would not fill it. Any damp layer between t he filler and the SS will be a worse corrosion condition. Many shafts are solid SS. In theory a thick wall hollow tube is almost is strong as a solid shaft, so I suppose on paper engineers think it's good and saves weight... in reality it's a perfect place for corrosion to start and any small IGA attack doesn't have far to go for failure. JMHO! .

[rognvald]

Originally Posted by Cheechako

Personally I would not fill it. Any damp layer between t he filler and the SS will be a worse corrosion condition. Many shafts are solid SS. In theory a thick wall hollow tube is almost is strong as a solid shaft, so I suppose on paper engineers think it's good and saves weight... in reality it's a perfect place for corrosion to start and any small IGA attack doesn't have far to go for failure. JMHO! .

Cheechako,
And if the shaft is already partially filled with a mystery filler(pourable foam that has degraded over the years into a less than hard surface?) would it be helpful to seal with a layer of thickened epoxy?

[cal40john]

Originally Posted by crazyoldboatguy

The bend is deliberate - part of the shape of the shaft where it enters the prop aperture. I should have described it better. There is no way to know what technique was used to create the bend. I highly doubt it is 2 pieces brazed together. Probably was heated and then bent in a hydraulic brake press of some type. If not heated properly and bent too quickly, the internal structure at the bend could be too weak.

Naval bronze. That's the name. Probably what it was made of. I may rely on a surface test using penetrant and developer - I used enough of it as a welder in the ship yard I worked at in the 70s. I may remove some material and have it tested to see what alloy it is just to make sure it ain't brass. I had a prop shaft for my Pearson Triton made by a machinist. He wasn't familiar with nautical materials and decided I should have brass, not bronze. It was too close to launch time so I went with it. Replaced it the next year. Even in fresh water I would not want to depend on that soft material for long. I will definitely sand and check for the pink spots. That is certainly the easiest thing to do right off.

Thanks to both of you for responding.

Naval bronze is a misnomer, it is actually a brass with around 40% zinc. Seen it called both Naval bronze and Naval brass. Manganese bronze sometimes used to make propellers is also a brass. A blade fell off a friends prop, pink all the way through.

Cal Plastics and Metals

[Cheechako]

Originally Posted by rognvald

Cheechako,
And if the shaft is already partially filled with a mystery filler(pourable foam that has degraded over the years into a less than hard surface?) would it be helpful to seal with a layer of thickened epoxy?

Not sure... foam would be bad as it holds moisture. You can likely dissolve it with Gasoline or other petroleum stuff....? I'd get as much out of there first. I'm no expert.
How about remove the foam and put a SS rod in there just undersize held with structural Epoxy? !!