Brown spots on sanded hull

Jul 31, 2019
9
Hunter Hunter 31 Southport NC
I am looking at a Capri 22 for sale that has had its bottom partially sanded. I am a newbie to bottom sanding, but there are multiple brown spots about the size of a quarte and a bit larger. Is this a serous gelcoat issue or is a good application of bottom paint all that is needed ? See the attached images.
 

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Feb 16, 2017
164
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They are previously blister(s). They were dremeled out and they filled with what appears to be West Systems epoxy and micro balloons.
Are those grinding scars all over the boat bottom?