On My Wheel House Roof Is Painted With A Very Rough Paint And Needs Redoing, Im Told That Masonary Paint Is Used For These Areas! The Local Chandery Has No Idea, Does Any One Know?
Might well be masonry paint. Some of the marine paint mfrs do 'deck paint' which is loaded with fine aggregate for a non-slip finish. My preferred technique is to mask out the areas you want to make non-slip, paint with you chosen topcoat, then sieve on dried silver sand. Once dried and after another couple of coats of paint you'll have neat non-slip areas for minimal cost.
International do an oil based deck paint branded as Interdeck which I used for several years.
However, I have just taken the plunge and painted the decks with Sandtex from B&Q which is a water based acrylic. A five litre can costs about the same as a 1 litre of Interdeck. Unfortunately they only do the textured stuff in 5 litre cans while the smooth is in 2.5 litres which would have been enough.
The Sandtex goes on far better than Interdeck with a roller and brush and dries more quickly. Abrade the old coating well with a belt or random orbital sander. If you try and paint over contaminated and UV affected paint, even textured, the new stuff will come away in sheets.
Trust me. I write from experience.