Renovating a 1975 20' Sceptre

[kiwi]

I'm a rookie at posting here and also at boat renovation. I have a 20' Sceptre with dings, some keel delamination, a crapped out old 175 Johnson, etc. so I decided to strip everything off the hull, sand and paint it, remotor, rehelm, new guages, the works. I've just started sanding off the bottom paint, and found that whoever worked on this before me did a hack job. There are thousands of sanding scratches imbedded with bottom paint, requiring me to sand off quite a bit of gelcoat to remove them. Many are deep enough that I have to sand down to the glass. I did rough sanding with a soft pad on an angle grinder and 50 grit. I smoothed it with 80 grit on an orbital. But the radius in the chines is trouble..lots of gouges in these. Anyone have any tips on how to sand in the chine radius? I was planning on using the end of a belt sander....dumb idea?