Ya I wasn't sure if I've heard of this before but I keep running into it and it sounds really helpful for traveling long distance in a ship.
Here is another link:
http://guide.uo.com/skill_12.html"Hint: Cartography can be a handy skill for boat owners. Plot your course using a "sea chart" map, and then give the map to the boat's tillerman. Say "Start" and your tillerman steers the boat on the course you have plotted. "