Hi splax:
Is the photo showing the tan non-skid your boat? Or another's that you are showing for reference? I can't tell because you mention you want to do light blue. And the second picture is of a boat with only white on the deck ... inferering that your project hasn't started yet?
If the tan photo is your boat, then disregard my following comment. You are all ready well under way with the project. And you are asking the forum for opinions about the color scheme.
If it's another boat in your marina and you haven't started doing anything yet, my opinion is that painting over OEM non-skid gelcoat should be avoided unless the OEM has become worn, or damaged, or is stained so bad that no cleaners or oxylic acid products (for removing tanin and rust stains) will restore to an acceptable appearance. I suggest this because one-part paint only lasts for so long before chaulking, wearing down or flaking off. Once painted, if you are particular about appearance, then you might need to do all over again every 3-5 years or so. And every new coat doesn't look as great as the first.
In my case, for my 1980 Hunter, by 2009 the physical integrety of the OEM non-skid was still fine. But appearance was bad and also I was concerned that in not too many seasons, it would begin to degrade as my smooth cabin top gelcoat already had. I painted my non-skid with Interlux's Perfection 2-part polyurethane mixed their flattening agent (to reduce gloss) and anti-skid granuals. The OEM color was off white. I opted change to a extremely subtle tan/grey hue because it's best that the new color not be too different than the underlying one. Being 2-part, the paint has held up excellennt even after 6 years. Still looks much like the day I painted it. I don't think one-part paints will do as well over time.
