I actually did some historical research for these too! The Royal Navy itself has a page on uniforms throughout the ages. They appear to be a mix of a couple of periods, so I stayed with the colours that looked pretty standard - white trousers and cross belts and red coats. Did you know e redcoats weren't because they didn't show the blood, as popular myth would have it, but because red was the cheapest material available at the time? And that's straight from the horses mouth too.
The officer gets a natty blue coat to help his stand out.
These chaps may face off against my pirates at some point if I run a game, but don't hold your breath!