gunnels on my big boat need some love. Looking for advice wet sanding. Ive done auto body , shower/tub repairs. Rough fiberglasser, great sander. I ve got electric and air sanders. Scared of the power sanders on fiberglass, sand thru factor. Anyone got a rough idea how thick gel coat is. Has to be thicker than a tub surround ,rite ?boat too big to do by hand ( i’m too old to fight ,too slow to run) All advice welcome. 18yr old H/S 22’ lts tunnel thx. Anyone use rejex , by corrosion X?