robertsconley
Hero
Theron said:"The Pilot's Almanac" for HarnMaster is one of, if not the best RPG books on the subject of medieval maritime trade. Most of the book is not system-specific. I don't see it on the Columbia Games website, but it's not too hard to find online.
EDIT: Sorry, I didn't notice the "free" part.
The Pilot's Almanac is indeed the best gaming reference for maritime trade. Fairly simple to use but feel realistic. Plus you get shipbuilding rules to boot. It can still be purchased here
http://www.columbiagames.com/cgi-bin/query/cfg/allharnitems.cfg
info is here
http://www.columbiagames.com/cgi-bin/query/cfg/zoom.cfg?product_id=4002