For bonding to alu, I got the advice to prepare the alu to be glued (sanding etc.), but the last thing to do, was to wet-sand the surfaces to be bonded with epoxy instead of water. I have not tried it yet, but it sounds like a very good idea. The guy who came up with this was trying to repair an alu track that had pulled off a carbon mast..
The problem with bonding anything to aluminum is that it 'corrodes' practically immediately when in contact with air. This tiny corrosion layer actually helps protect the internal aluminum (I'm NOT talking about anodizing) but it doesn't bond with anything well. SOoooo...if you can abrade the surface while keeping it from coming in contact with air (i.e. using epoxy?) then you might have something. I've never heard of using epoxy between the sandpaper and the aluminum before the idea certainly has merit. The sanding 'dust' might be considered a problem in the epoxy - but as long as it's minimal it shouldn't be much of a problem. Besides, if you add aluminum powder to epoxy, it helps it resist abrasion.
I recommend at the hound add a wear plate using 18 guage stainless. Attach with 4 small rivets and bed with 4200. 18 guage can be form bent by hand to fit the mast. the suggestion about using a pigtail is good but the wear plate will protect the mast and remedy the current problem. The black marks are the result of how the boat was trailered in the past. Clean up the best you can and live with it.
Damn. I was hoping no-one said to drill into the mast..... I HATE to drill into the mast. For any reason. And what is 4200? Sounds like a 3M product?
The nice part about being a pessimist is that you are constantly being either proven right or pleasantly surprised. - George Will "It's not that liberals aren't smart, it's just that so much of what they know isn't so" -Ronald Reagan
It's a 3m product. 4200 is 5200's younger brother. 4200 is not quite as permanent as 5200 and is prescribed for bonding to plastics to anything else. 5200 is not prescribed for plastics but works great between gelcoat, fiberglass, and metal.