correct bolts to use on an aluminum mast plate?

[laHolland]

When our mast was unstepped last fall we found that the aluminum mast plate is in good condition, but the the two bolts holding it down (deck stepped) were completely rusted away down to the plate base. There was some sort of black gooey cap over the bolt heads (what was left of them) that I guess was supposed to be a sealant, but clearly it didn't work. But to be fair, this is a 37 year old boat.

So obviously the bolts need to be replaced. It was a pain to get out the rusted remains, and we had to fill in the holes slightly (over-drilled by 1/4") with thickened epoxy.. Hopefully this will not be an issue? I wouldn't think so.

So the question is - what kind of bolts are the best to use next to the aluminum plate? And should we cover the new bolts with some sort of goo, like the old ones were?

[mitiempo]

Use stainless and coat mating surfaces with Tef-Gel to isolate them.

[SVPrairieRose]

Yup

[laHolland]

Thanks for the answer! I love it when there is a simple solution to a problem.

[brak]

For coating you can also use a polyurethane sealant like Sikaflex or 3M (I prefer 4200), as long as it creates a non-permeable membrane between the bolt and the aluminum. Since you probably will use sealant anyway.