Comments about 3M 3M Super Duty Compound:
Bought a 1979 Oday sailboat for my wife and the hull and top decks were badly oxidized. Did the hull first and went over the hull twice and still could have done more.
On the top decks that have baked in the sun for 29 years I wet sanded first with 150 grit wet-n-dry sand paper, then with the 3M Super Duty Compound. May go back to the hull with wet sanding and polish again after seeing how much the sanding helped.
In other words it is a "super duty" comppound, but wet sanding first can save a lot of polishing if you have bad oxidation. Be carfulwith the sanding. There is only so much gelcoat.