Trojan Boat Forum

I need to replace a bent rudder shaft and was wondering if it could be replaced with stainless and if not, why???

Thanks

yes it can, and much better. in my opinion.

wowzer52 wrote:yes it can, and much better. in my opinion.

Not so fast, quoting some experts in galvanic action:
"Generally, it is a bad idea to use stainless steel underwater, because it can pit. When it pits the "nobility" of the metal changes locally, and you end up with tiny galvanic couples that are made up of different parts of the same piece of metal and the pits grow deeper. One school of thought suggests that if you must use stainless steel underwater (e.g. you need its strength), then you should connect a nearby, immersed zinc to it; this protects the stainless steel from itself, reducing the rate of pitting. The electrochemistry of this assertion is compelling enough to recommend that you protect a stainless steel rudder shaft with a zinc. This may be done by mounting a zinc on the hull near the rudder shaft, and electrically connect it (inside the hull) to the stainless rudder shaft. For the reasons described above, ensure that your metal rudder shaft is not electrically connected to anything else. Your stainless steel propeller shaft will be protected from itself, by the same shaft zinc that protects the propeller from the stainless steel shaft. In both cases the pits, if they appear, will appear where the stainless steel is not exposed to the water. Trouble areas are in the cutlass bearing, inside the rudder bearing, and just inside the top of the rudder."
Reprinted from West Marine's West Advisors http://www.sailmail.com/grounds.htm

Just another viewpoint to think about... how often do we disassemble the rudder assembly to spot this potential pitting in the rudder bearing assembly?

I also think you would be better off with the stanless shaft many rudders are made wtih stanless shafts just like most boats have stanless prop shafts yes I have seen pitted shafts but I have seen proplems with broze shafts also ( and monel also) . its really no issue just keep good zincs on as you should no matter what you have .

you should have zincs on your rudders anyway

SS rudder shaft will be fine if you never run aground again. If you do you risk ripping the stuffing box out of the stern and leaving a 6 inch hole in the bottom. Rudder shafts are bronze because it bends easily.

excellent point that i didn't think of at all. i think i'll stick with bronze!!!