At that scale we can pretty much ignore a lot of the finer details.
Let's face it, SB Scale is right on the edge of workability for the old sailing ships. We're talking most rigging that should be 1/2 pixel wide or finer. Ditto on decorative woodwork details.
I sit back and focus on the highlights and deep tones first, trace where I can. Were aiming for "verisimilitude".
the appearance of being true or real.
Once I'm reasonably satisfied I then play with shadowing to enhance definition, create depth, etc. In actuality we end up with with a lot of semi-defined noise if one zooms in to 800x (in MS Paint as a universal example). The shadowing is always color tones related to the important part, be it highlight or background body shape.
It helps to know the structures you're looking at but not critical. One can get a pretty decent understanding of the shapes and how they fit together by burning an evening Googling images of these ships. Look for period artwork, ship model galleries, etc. since there aren't too many of these ships around.
See if these help:
http://step.polymtl.ca/~coyote/drawingsd/drawing07.jpg
http://step.polymtl.ca/~coyote/drawingsd/drawing05.jpg
http://step.polymtl.ca/~coyote/drawingsd/drawing03.jpg
http://www.the-blueprints.com/blueprint ... tory-3.png
CraigH