Rudder Post Electrolysis

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Tom
Posts: 23
Joined: Sun Jan 18, 2009 7:43 am

Rudder Post Electrolysis

Post by Tom »

Help,

I just put my newly acquired PH 39 on the hard and found what appears to be electrical corrosion around the rudder shaft at the top of the rudder. The corrosion appears to be about 3/16 to almost 1/4 inch deep, does any anyone know the thickness of the rudder shaft on this boat or anywhere I can find this info.

Thanks,

Tom

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Michel
Posts: 546
Joined: Sun Dec 07, 2008 5:48 am
Location: Zaanstad, the Netherlands, EU

Re: Rudder Post Electrolysis

Post by Michel »

Tom,
I had the same problem on my 1981 F44 #4, the corrosion was all around the shaft at the entry point of the hull. In my case, it was not as deep as you describe. On the F44 the shaft goes all through the hull and exits in a well in the cockpit where the quadrant is, so you can have a good look on top of the shaft. The upper part of the shaft is hollow, and the foot as well. From memory I'd say the wall thickness of the hollow part is about 1/2" or maybe a bit less. I have no idea if the shaft is hollow all the way; I always have some water standing in it, but there is a floor half a foot down the shaft. It may be solid further down, but it also may be filled with resin or something else. If the shaft is hollow, your shaft may be gone halfway! The area just above the rudder is the part with the greatest torsional forces, so you might have a problem there.

I don't know about the F39, but the F44 has a full skeg. I removed the shoe at the bottom of the skeg and took out the rudder to check the shaft. You can have a look at how it all looks down there at http://www.flickr.com/photos/alabama_queen/ You have to go back a bit in the set of photos to find the rudder stuff. I also found that the bottom of the skeg had very little glass in it and mostly resin, something Marno of F39 'Attitudes' also found. You can consult him about the rudder, he did a lot of work on it. He also has a good set of photos of the rudder work on his website.

I mounted an anode on the rudder with a screw connected to the rudder shaft to prevent further corrosion.

Hope this helps you a bit further.
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

marno
Posts: 53
Joined: Sat Dec 06, 2008 6:21 pm

Re: Rudder Post Electrolysis

Post by marno »

This is mostly about the skeg repairs I did, although I did drill some test holes in the bottom of my rudder to see if it was wet (it was a little). I may have some shots of the exposed shoe, if you want them let me know and I'll go hunting.

http://www.yachtattitudes.com/skeg_repairs.htm
Marno

F39 Express

Tom
Posts: 23
Joined: Sun Jan 18, 2009 7:43 am

Re: Rudder Post Electrolysis

Post by Tom »

Gentlemen,

I had intended to add a wire from the bolt attaching the quadrant to the rudder shaft and attach the other end of the wire to a large anode. When I checked for current flow from the lower portion of the rudder shaft inside the hull up to the quadrant bolt, there was no current flow. The rudder post inside the hull looked like carbon fiber and the outside portion above the rudder looked and was metal, I thought bronze but today learned stainless. Based on this, I decided to attach a small anode on the rudder directly to the rudder shaft. I drilled a hole about two inches down from the top and two inches aft of the leading edge and expected to hit metal, went all the way into the shaft and water started running out of the hole, no metal.

I called Paul Dennis, who worked at Freedom during the time my boat was made and he told me that Freedom used a stainless sleeve around the carbon fiber shaft on the top of the rudder as a surface for the bearing to ride on. He said that the corrosion I had would not be a problem. Also, the water in the rudder should not be of concern since there is no metal inside, to corrode and as long as I am not in an area where the rudder might freeze, no problem.

What could have been a very expensive or long term personal repair turned out well.

Thanks for your input.


Tom

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