I did a ton of that kind of research for my naval campaign a few years back.
Generally, I found the following rules of thumb:
a ship is 2-6 times as long, as it is wide (there are exceptions, but it is close enough)
A ship's draft is about 1.5 times the width. If I recall, Draft was the amount of ship below water. i used the term to mean the total height from the main deck, to the below decks. What was really after was how many decks was the ship, assuming 10 feet (2 squares) per deck.
a ship's sails had a logical height limit. I think I used the ship's length as an approximation of that.
I also guesstimated that the number of masts would be limited by the length, something like 1 per 15 feet.
I'd have to hunt down my actual notes, which were a bit more mathematically sound.
I had made a spreadsheet of a ton of known sailing ships, and their height, width, draft, # decks, masts, mast height and then eyeballed that into my own "ship construction" guidelines.
I also packed on a lot more weaponry than most published books have. After seeing Master and Commander, and realizing that navy warships were about packing on the guns, it made sense that in fantasy, even with ballistae and catapults, they'd be packed in as best as they could. Given than most published D&D ship designs had maybe 4 or 5 weapons, that was a huge change.
