Compass

#Equipment
First developed in China and later introduced to the Near East and Europe, a compass has a magnetic needle that points to magnetic north (or, in China, magnetic south). There are two versions:

• Magnetized needle to float in water (requires a bowl or dish of water). Allows unmodified Navigation rolls. $5, neg.
• Magnetized needle on a pivot. Gives +1 to Navigation rolls. $25, 1 lb.
  It’s possible to judge headings astronomically without a compass, if the sky is visible: -1 to Navigation to steer by the pole star, or -2 by other stars or by the sun.

Source: GURPS 4th - Low-Tech, page 54