H-26 Rudder Head Corrosion

[BrianW]

I was recently sailing in my 1994 H-26 when the lower portion of my rudder completely seperated from the lower pintle mounting. The rudder head, the pair of large aluminum plates holding the rudder, completely corroded through where the stainless steel bolts attach the rudder head to the pintle (see attached photo). I suspect two possible causes. The first possible suspected cause was because the previous owner used bottom paint on part of the aluminum rudder head. Even though I removed the bottom paint, the area painted was visibly pitted. Another suspected cause is from galvanic corrosion (dis-similar metals) from the stainless steel mounting bolts in contact with the aluminum rudder head. In both possible causes, the corrosion occurred only at or below the water line. I sail in salt water. I'd very much appreciate your ideas, especially H26, 23.5 and 19 owners with similar rudder designs. Causes? Prevention? Should I buy a replacement rudder head from Hunter or fabricate one locally? Thanks! BrianW

 

[Rick Webb]

What Kind of Bottom Paint?

Copper based bottom paint on aluminium in salt water is asking for corrosion. I added weight to the front of mine to balance it out better it brought the lip up out of the water.

 

[BrianW]

Bottom Paint

Rick, the bottom paint was Interlux Micron CSC. Loaded with copper. Thanks for the weight balancing tip. BrianW

 

[david king]

Zinc

Brian, I sail my 1997 h26 in salt water also. In 1998, the first year I owned her, I hauled out for inspection prior to the sale and discovered metal damage to the s.s. centerbord pivot assembly, the ballast tank valve, and to metal parts of the rudder that were in contact with the water while at the pier. This in only one year! I had it all fixed and then wired everything together. I ran a wire from the mast support pole (which is in contact with the rudder assembly) to the tank valve - all this inside the boat - and continued the wire outside the companionway hatch, over the side and attached a small zinc. That was 1998. I've gone through a few zincs and have had no problems since. Oh yes, I switched to an 8 h.p. 2 stroke motor that is light enough that the metal parts of the rudder are no longer in the water at the pier. Molly has been in the water all the time for the last 8 years. Last haulout was a month ago. Everything was fine. David King "Molly"

 

[Rick Webb]

Weight Up Forward

Took about #100 pounds additional plus moving the batteries. Moving #10end for end is the same as adding 20 if there are things in the aft end that you can move forward.

 

[alan]

Do u have shore power?

I've heard that could in part do it. My rudder has sat in salt/brackish water for the past seven years. Very little corrosion. I "rebuilt" it a few years ago and used nylon washers to isolate the stainless bolts from the aluminum but there was only a little corrosion without those. alan

 

[BrianW]

Shore Power

Yes Alan, I have shore power. Are you thinking stray current? BrianW

 

[MABell]

Some pitting on mine

My first thought was stray power leakage (shore power), but on a boat like the H26, nothing is connected (grounded) together. The pintles for the rudder are bolted through the fiberglass.I was thinking about mounting some zinc right on the edge of the rudder – but that wouldn’t do anything for the pivot mount of the center board, as pointed out above.Lastly, the electrical problem may not be your boat, but someone near by.It’s enough to make you want to obey the no swimming rules around a dock.

 

[Fred]

It's not the stainless

Stainless and aluminium are pretty compatible if they're marine alloys. The fellow who wired everything together and used a "fish" (zinc over the side) proved it works, because he's losing zinc.If you have shore power, especially if you keep a battery charger connected, ther is potential (pun intended) for stray current.A good source for zinc for your fish is discarded zincs in the boat yard. A zinc off a fish boat that's half gone still weighs a couple of pounds.I watched a guy leave the dock with his "fish" still over the side with the wire wrapped around his propellor shaft once, but that's not electrolysis damage, exactly.

 

[BrianW]

Stainless Rudder Head?

Would there be any benefit in replacing the aluminum rudder head with a locally fabricated stainless steel one? To save on the extra weight if SS is used, could thinner plate be used? Would the extra weight even be enough to worry about or easily corrected by bow ballast? Just looking at all of the possibilities. Thanks, great responses! BrianW