New trailer

[moonlight]

Potcake, in this case, a picture would be worth a 1,000 words.

The rudder stock is unlikely to be bonded in any fashion; AND unless you're in the water AND bonded AND connected to shore power (grounded to the electrical system, providing a faster path to ground than going around you), stray current would not be the issue.  IF you have any dissimilar metals, in an electrolyte (salt or brackish water), that alone makes an electrochemical cell.  Stainless Steel and Aluminum commonly interfere with each other, and in that case the aluminum loses.  Like a stainless bolt through an aluminum rudder?  Aluminum loses.  Overdrill it, if not done already, and put a nylon or delrin bushing.  Always bed stainless hardware going into aluminum, if not with a nylon spacer, at least with blue Loctite, which creates a barrier.

Are you inboard, for the propeller shaft zinc?  Or is that on an outboard?  If an inboard, that ANODE protects the bronze prop from the stainless shaft; lose it, and all the zinc leaves the bronze prop, rendering it a bright red copper prop, which is infinitely more maleable (soft, brittle) than the hardened bronze (which is why they added the zinc to the copper in the first place)...

[Gus]

On a side note, I ordered some parts from Hutchins last Thursday, and I've got the box in the mail yesterday. The new mast step is a bit different, I'll post a picture when I can.

[Potcake boy]

Moonlight,

I use Lanacoat to isolate dis-similar metals. I would be happy to see Com-Pac eliminate aluminum all together in their rudder stock. I really like the Ruddercraft  setup, because it is all stainless, and it raises 180 degrees. Some of the worst corrosion was in the gudgeons especially the bottom. I was going to replace the bronze bushings with nylon, but they were pressed in and the corrosion made them fast. When I re-installed them, I packed them with Lanacoat. Hopefully they will last a while. I do believe the only proper solution is the eliminate the aluminum and go with stainless. My pilothouse has wheel steering from within the cabin so there is a stainless piece connected about midway on the rudder stock casting that transfers the torque to turn the rudder. I would probably need to do some custom work to fit that to the Ruddercraft rudder stock. For now I did my best to provide a reasonable repair and hopefully get a few more years before I have to again confront this problem.

The zinc on the propeller shaft is fine. I understand why there is corrosion around the rudder stock, it's galvanic, I sail the boat in saltwater and the rudder stock is partially submerged. There is no bonding system, the through hulls are plastic, and I almost never use the shore power. I have a solar panel that keeps the batteries topped up when at the dock. I have been raising the rudder when docked, but the pitting was over areas that were not submerged when the rudder is up. Considering the prop shaft zinc hasn't shown accelerated deterioration, I can't suspect stray current in the marina.

Thank you for your observations, I'm happy when fellow sailors share their knowledge with the community.

[Potcake boy]

Back to the trailer topic:
My trailer is a 2013 Magic Tilt, and has a keel bunk with a plastic slide pad covering it. The bunk is wooden, probably a 2"X 8" and is supported only by the three crossbar supports. Problem is that the front and back supports are spaced too far apart and aren't under the keel. As a consequence the wooden bunk is bending severely especially the front because there is no support under it at that point. In fact, the bunk board is not splintering. Has anyone else experienced this problem?

[ruffwind]

Regarding copper anti fouling paint on aluminum.  5 years ago, I used Interlux 2000 barrier coat on my whole boat and the aluminum rudder blade.  I have painted the rudder blade every year with VC17 bottom paint.  I keep the boat in the water on Lake Michigan for 5 months a year.  I don't show any electrolysis to the rudder.  Is this because of fresh water?

[Potcake boy]

I would think the barrier coat is to credit as it prevents contact between the aluminum rudder and the copper in the paint. I have the foil rudder, but epoxy coated the aluminum stock and bottom painted. Haven't had it back in the water yet, so we'll see. Hope I have the same result as you.