Leeway is the lateral movement of a ship to the leeward of her course; drift. Just as a vessel's course is affected by the current of the water (set and drift), her course is also altered by wind. Vessels with greater surface area on the beam experience more leeway than ones with less.

A navigator on a vessel must adjust his ordered course to compensate for this alteration. A good rule of thumb for adjusting ordered course is to alter your course by six degrees for every knot of drift on the beam. For example, if a navigator wants to make course 090 good, but there is one knot of drift to the south, the adjusted course should be 084. Failure to make these adjustments during a voyage is negligent and will yield poor navigational results.