In the last 2 weeks we have have had -15C weather, a wedding,  a chest infection and a boat show but still managed to start sanding off the anti skid from the deck.  I know that the deck had been painted with house latex paint so knew it had to be removed.  Only after I started did I see how thin the gel coat was, before I sanded to the bottom of the diamond pattern the under layer of resin began to show.

This image is of the coach roof after sanding , the dark area's is resin .  The next one is a close up of same area.  Not much to look at but does show the diamond pattern in gel coat.

Have to start the deck but before I will identify wet areas that have to be removed ,no point in sanding these parts.  I have also started to sand off the old Cetol from the teak trim pieces and cupboard/door frames.