Material for galvanic insulation

[Kenneth K]

I just pulled the boom vang plate from the bottom of my mast. Was just going to just reseat the 8 SS screws in Tefgel or DuraLac, but after seeing the state of corrosion, I'm thinking about doing more. Seems I've read of others installing an insulating fabric or membrane between AL and SS parts. What did you use for this?


The grayish flakes in the second pic are the back-side of the black anodization that peeled off the mast and stuck to the plate. The white flakes are clumps of oxidized aluminum "powder." The mating area on the mast is full of this "bubbled" aluminum powder.

 

[Christian Williams]

Well, I don't know why a membrane would be better than Tef-gel on the screws. But since I have some 1/8th nitrile lying around, I'd probably use that.

 

[Kenneth K]

Yes, a liquid treatment for the screws, but it seems a "sheet" would be better for the large, flat surfaces of the plate.

Where can I get small amounts of nitrile?

 

[toddster]

3M Scotchrap. Comes in 3-inch wide tape rolls, among other shapes. Also handy between aluminum mast base and stainless steel mast organizer. etc.
(Catalina Direct lists a delrin membrane in their catalog, but when I ordered a piece of this very expensive stuff, it was only a piece of ordinary vinyl Scotchrap. Guess what? No returns accepted from non-Catalina owners.) For that matter, you can order a sheet of 1/16" delrin - I have some for making shims...

 

[Kenneth K]

3M Scotchrap.

Perfect, thanks. Says its 10 mil thick which equates to less than 1/64th inch. Probably about right--not looking to "float" the fitting, just insulate it.
By any chance, would you know if this stuff is similar to Preservation Tape (something else that's been on my Amazon shopping list)?

And, where'd you get the 1/16th delrin sheet?

 

[toddster]

IDK and... I think it was probably Grainger.

 

[bigd14]

McMaster-Carr

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McMaster-Carr is my go to for all manner of esoteric stuff!

 

[Parrothead]

McMaster-Carr silicone gasket material #8525T577
I used it for all of my foot mounted mast hardware and winches, NOALOX on all machine screw threads and absolutely no sheet metal screws.