Corrosion to rudder stock

[Potcake boy]

Are any of you experiencing what might be considered excessive corrosion to the aluminum components of the rudder stock and gudgeons?

I'm in the process of annual rejuvenation of my 23 and decided to pursue the visible corrosion on the rudder stock so I removed all the components to refurbish and repaint. The pitting on the aluminum plate extending from the rudder was obvious and the surface corrosion on the cast piece that is hung from the gudgeons. The surprising find however was the extent of the corrosion of the gudgeons. Because of the steering on my pilot house, the gudgeon is in two pieces divided by the opening for the wheel steering link. The bottom was far more corroded than the top so I will reverse them to extend their useful service life. I recognized the bronze sleeves to be the galvanic corrosion culprit, but was surprised at the level of destruction. I'm no chemist, but it appears that the coefficient of galvanic corrosion is far greater between bronze and aluminum than that of stainless steel and aluminum.The corrosion was centered around the bushings and went about 20 percent of the depth. It was not visible until I dismounted he rudder. I am aware that earlier this year our marina had stray current from faulty wiring in someone's lift, but my prop shaft zinc was OK. The only time these components are submersed is when underway. I am wondering if having an inboard has contributed to this problem, as I don't remember having the same problem on my Com-Pacs with an outboard. I may contact Gerry at Hutchins and raise the question of using some plastic material like Delrin for the bushings. I have used plastic milk jugs to provide rudder bearings on several boats, and never saw any wear out.

I would appreciate feed back of personal experience of this nature to share with all the members.

P.S. If you haven't already, it may be a good time to inspect your boat, as a rudder failure on open water is not anything to take lightly.

[Bristol14]

I rehabbed my rudder on my '87 23 MK II two years ago.  It had a stock rudder and I replaced it with a foil rudder from Hutchins. The rudder housing had some pitting but I didn't think it was excessive given the age. I replaced the bronze bushings with stock bushings from Hutchins too. Neither the old bushings but the seats the bushings sit in were pitted. Instead, the old bushings were worn. I did think it was odd that the bushings were bronze. Seems like stainless steel would have been a better choice.

Also, my rudder has a zinc strip attached to the bolt that secures rudder foil to the housing.

[brackish]

I did mine a year ago.  I only found significant pitting on the part of the blade that the foiled rudder is attached too, filled it with thickened epoxy and repainted with zinc chromate then a finish coat.  I had bought all the parts for rebuilding the pivot points, bushings and bolts, but found no play so I just assembled with the old stuff.

finished below, I can't find the in process pics.

[Potcake boy]

Backish,

Thanks for the feed back. A couple questions if you would:
1. Are you in salt or "brackish" water, or fresh?
2. Did you find there to be no corrosion around the bronze bushings?

I was thinking of doing the same process of a coat of epoxy, then painting the lower part of the rudder stock connected to the rudder. I would also overlap the top of the rudder because I found there to be some water intrusion, which can't be a good thing.

[Gus]

I can't get the bolt out that attaches the rudder to the housing. I left it soaking overnight with WD-40, but that think is seized in place.

[Bob23]

Gus:
  PB Blaster is much better than WD. And don't be afraid to heat with a propane torch. Heat, soak, repeat, try to turn it a little..it will eventually loosen but it will fight you. I've been through this. Now everything gets coated with Never Seize on assembly.
  And Potcake: Zincs, zincs and more zincs. I think I have a total of 8! 1 on each end of each bolt. One near each tab  of the gudgeon although the lower tab is what really gets eaten up in the salt water I sail in. One on the rudder blade itself and one on the body of the housing. This is just from memory....I might even have more! They will work...just don't paint 'em or apply them over a painted surface.
That is all men, at ease!

[brackish]

Backish,

Thanks for the feed back. A couple questions if you would:
1. Are you in salt or "brackish" water, or fresh?
2. Did you find there to be no corrosion around the bronze bushings?

I was thinking of doing the same process of a coat of epoxy, then painting the lower part of the rudder stock connected to the rudder. I would also overlap the top of the rudder because I found there to be some water intrusion, which can't be a good thing.

Ron, I'm in fresh water most of the time, but have towed to the Gulf on three occasions and have been in the salt for several weeks at a time.  I do lift my rudder when at dock, but the leading edge stays in the water about an inch.  I did have a crack around the top of the fiberglass rudder stock where the aluminum blade exits.  When I did the refurb I used a sealant in that crack to try to keep the water intrusion to a minimum, can't really say how it has worked but there is nothing seeping out of there when I lift the rudder parallel.   I used some compound I had left from building my fuel locker cover to seal the teak strips which I'm sure is similar to Boatlife polysulfide.

while the area around the bronze bushings was powdery I found no significant pitting.  I painted all components of the system with zinc chromate, then a top coat of an auto paint used for aluminum.  Looked good when I finished, too early to tell about longevity or protection.  I think it is something that will have to be done every five years or so in the life of these boats.

here is a link to a pic of the rudder damage and some discussion about it.

http://cpyoa.geekworkshosting.com/forum/index.php?topic=10346.0

[Gus]

Gus:
  PB Blaster is much better than WD. And don't be afraid to heat with a propane torch. Heat, soak, repeat, try to turn it a little..it will eventually loosen but it will fight you. I've been through this. Now everything gets coated with Never Seize on assembly.
  And Potcake: Zincs, zincs and more zincs. I think I have a total of 8! 1 on each end of each bolt. One near each tab  of the gudgeon although the lower tab is what really gets eaten up in the salt water I sail in. One on the rudder blade itself and one on the body of the housing. This is just from memory....I might even have more! They will work...just don't paint 'em or apply them over a painted surface.
That is all men, at ease!

Bob, thanks for the tips, I didn't think about heating the bolt out.

[Potcake boy]

Thanks to all that contributed accounts of their experiences. I am concluding from this conversation that correcting this corrosion problem will be an on going maintenance items as long as I continue to sail in salt water.
I really like the idea of the Rudder Craft rudder which has a stainless stock and allows the rudder to swing all the way up, but I don't think there would be a way of connecting the wheel steering link to the rudder stock.
I suppose a part of the lure of boat ownership is the promise of something to fiddle with for the period of ownership. It's a good set up for a cold beer.