- Dec 30, 2009
- 680
When rebedding my chainplates,there are approx, 2"x3" back plates underneath. They are 1/4" ss, would it be a problem installing 6x6" aluminum plates first, then the ss. Will the difference of metals be a problem? Red
chainplate backing
- Thread starter redhead78
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Yes, there will be a problem between the metals.
But, more importantly, why are you even considering it?
But, more importantly, why are you even considering it?
Putting the two metals together connected by a bolt immersed in seawater would be a problem. Keeping them dry (inside the hull) should not be as much of an issue. Make the hole in the aluminum plate larger than the bolt (so it can be filled with an insulator like 4200 and place an insulating gasket (like a piece of thin neoprene or non permeable plastic) between the aluminum and the SS plate. No current can flow and it is dry inside the hull, so it should be fine.
I would advise against it. It sounds like you want it on the topside of the deck, like others have said that would be a bad idea because of the different metals and the amount of moisture that it would exposed to. The more moisture exposed to two metal contacting each other just speeds up the process of the "irritation" of the two metals.
I wouldn't worry to much about reinforcing the topside of your chainplates but focus more on the inside. Those aluminum plates should be great for adding alot of strength to the chainplates, from the inside of course.
I wouldn't worry to much about reinforcing the topside of your chainplates but focus more on the inside. Those aluminum plates should be great for adding alot of strength to the chainplates, from the inside of course.
If you want to distribute the loading over a wider area than your 3x4 backing plates provide, a substantial plate of either durable wood like white oak or one of thick fiberglass would serve as well as the aluminum you were considering without the dissimilar metals problem.
You can use the butyl tape in between the two plates and it will not be a problem. Make a sandwich as it were, just be sure that the bolts don't touch the aluminim. Its a good way to spread the load over more area.
Plan B ?
Rather than get into the whole issue of bi-metalic corrosion, why not fab your a backing plate out of G10/FR4 fiberglass plating. Comes in oodles of thicknesses and is not a conductor.
Check out McMaster Carr, on line, or your local plastics dealer if you are near a metro area.
LB
Rather than get into the whole issue of bi-metalic corrosion, why not fab your a backing plate out of G10/FR4 fiberglass plating. Comes in oodles of thicknesses and is not a conductor.
Check out McMaster Carr, on line, or your local plastics dealer if you are near a metro area.
LB
I've read some blogs where people put a layer of electrical tape to the backside of S.S. before securing it to aluminum masts. Cheap and easy!!
I second the fiberglass suggestion. I have done just that and it works great. Not real pretty but functional. If you want pretty try the wood mentioned above. SC
I am about to do the same thing as you, but i am going to use plywood. My chain platies are secured only by the deck, and are stainless plates, only thing holding them down is the deck, i am going to cut larger sheets of plywood, attach them under the deck, then cut the slots for the chain plates to go through, then attach the chain plates to the glassed in plywood.
Since you already have the aluminum, you could have it powdercoated..or just use lanolin as an isolator. Spread it liberally between the plates. I have aluminum chain plates, and stainless bolts. I replaced the 30 year old bolts 8 years ago, powder coated the original chain plates, and have had no issues.
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