The "black" paint during the Nelson period seems to have been a pretty honest-to-goodness black. My personal approach is never to use pure black on a ship model; in this case I'd probably tone it down with a little blue and a little grey. The yellow on the stripes seems to have been a rather dark yellow ochre, which probably faded (i.e., lightened) over time.
Model Shipways (available through Model Expo, at <www.modelexpo-online.com>) sells the only broad range of paints intended for sailing ships that I'm familiar with. I've used quite a few of their colors, with mixed results. Some of them work fine - about like PolyScale, which is my current favorite. Others (the blues seem to be especially problematic) don't work so well for me; they have a thin, waxy consistency that doesn't cover well. But in terms of color I think they're pretty trustworthy. I believe the website includes color chips - not a hundred percent reliable when they're rendered by your printer, of course, but a reasonable place to start.
Painting a sailing ship model is a good bit different from painting an aircraft or tank - or car for that matter. There are no hard rules about colors - no government-sanctified mixes, etc. You're largely on your own, and there's plenty of room for personal judgment and taste.
Hope this helps a little. Good luck.
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