Just a quick overview. Re position of islands no bother to me. As far as that goes you have answered your own question. Unless it is part of the plot or historically correct avoid islands in the middle of the mat. I would say the game surface is OK if you bare in mind for small ship actions a smaller mat will keep them in contact better and speed up the game rather than have them wandering off all over a large area.
Now the wind. In one the wind favours red, In 5 the wind favours yellow and they should get to the island choke point in time to dictate the action. Eight gives yellow the wind but should no influence things too much. In thirteen the wind favours yellow strongly. If I were playing these scenarios, I would give your less experienced player the wind advantage.
I am sure that better sailors than I will come along to offer their expertise, and Raffer J Larwood can tell you all about the dangers of running onto islands.

Rob.