bronze with aluminum - bad?

[imported_Jimmy]

I seem to remember that bronze and aluminum don't mix well. I have a cast aluminum masthead fitting that is attached to stainless steel wire with bronze plates and stainless steel bolts and pins. It seems like previouis owners have got away with this so far, but there is some corrosions in the aluminum. Can I somehow separate/isolate these parts or should I just replace the bronze with stainless steel (or is it OK since it is so far away from the salt water)?

[Buddy Sharpton]

Rigging is the ONE place where people's threshold of galvanic corrosion prevention methods and no-no metal combinations get swishy. Stainless wire and terminal fittings get pinned to bronze turnbuckles for good reason of fear of crevice corrosion even though S.S. turnbuckles are available, and to all manner of bronze straps and tangs fastened to the hull with bronze bolts, but using S.S. clevis pins and shackles as often as not as with bronze ones. All pass muster as good practice. The aluminum is the odd man out here's why- worse to capture water in the mating surfaces of the mast and boom end fittings with a dissimilar metal one and let all that corrosion and gall be hidden and mess up an expensive extrusion. Use a stainless pin or shackle to bear on the aluminum after coating with an anti corrosion spray like Boeshield and you've done your practical best.

[Buddy Sharpton]

SQUISHY not swishy. My apologies.

[Ian McColgin]

Stainless to aluminum works ok up there. Stainless to bronze is fine at deck level as well. I'd not attach bronze to aluminum anywhere.

[imported_Jimmy]

The spot I'm worried about has small bronze plates held to the aluminum masthead fitting with a stainless steel pin or bolt. Would putting a plastic washer of some sort between them help or would they still be too close?

[Ian McColgin]

Insulating is a very good idea. That's why winch bases attached to aluminum masts are commonly insulated.
Check Brion Toss's web site, esp some recent 'spar talk' threads for mounting goops to prevent corrosion at any bolt holes.