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Discussion Starter · #1 ·
I recently discovered a crack in my rudder shaft and will need to replace it. My boat is a 1984 Kirie-Elite 37 and the original shaft is (we think) 316 stainless x 32mm. My question is what type of stainless do modern boats use for rudder shafts. Is there a better material than 316 stainless for this shaft. The material will need to be welded to the paddles inside the rudder. It appears that the failure was the result of bending loads rather than torque loads.
 

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You might want to try one of the Aquamet alloys...which are often used for prop shafts. :) Aquamet 19 or 22 are probably better choices than Aquamet 17. :)
 

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Welding

Since you are welding to existing material whatever material you choose must be compatible. Probably the original material is best choice. Welding different materials togeather can be done but may require exotic rods and procedures.
 

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Ranes-

You shouldn't use aluminum in any situation where it is in close proximity to stainless steel, since it will get eaten away, since it is less noble than the stainless steel. The webbing in the rudder shouldn't be aluminum either.
 

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Discussion Starter · #7 ·
Rudder Shaft

Thanks to each of you for your input. In talking to the metalurgist at Western Branch Metals, we have decided to use Aqualoy 22 and increase the diameter of the shaft from 1 1/4 to 1 3/8. This will require honing out the nylon bearings in the rudder stock, but my local vendor see's no problem in performing this operation.

I had also found the information at the Jefa rudder site and had a extended conversation with Western Branch about the difference between Aqualoy 22 and Stainless 329 and 2025. They are very similar in composition, strength and corrosion resistant.

I'll post a picture of the break as soon as I get the shaft back from the vendor.
 
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