When at sea or on a large body of water, steering is done by compass. But steering by compass is an art unto itself. Most newcomers to compass steering end up all over the place.

Say you are trying to maintain a course of 200 degrees. You want to keep the lubber line (which is 1-degree in width) right on 200 degrees on the compass rose. But, suppose you get off course and steering 195 degrees. The helmsman must swing the boat’s head with right rudder to bring the lubber line back to 200 degrees.

Think of the lubber line as the bow of the boat. The compass card actually stands still, while the lubber line swings around it. And magnetic compasses do not react quickly as do digital and gyro compasses. There is a delay and even a reverse movement of direction of the compass. In our case above, you turn right to get the lubber line back to 200, but initially the compass will appear as if going to the left, rather than the right. And once you get to 200, the compass may keep on going to the right before coming back and finally settling down to its actual heading.

For the novice helmsman this can really drive you nuts. Often you will see a novice helmsman making a zig-zag course, yawing from side to side, trying to catch the compass. A straight course is the goal. To do this you make only slight movements and straighten the helm. Small changes in headings do not cause the radical reaction by the compass.

Even experienced skippers find ways to make it easier. Once on a heading, find an object to steer toward and use the compass as a reference. If no land is in sight, you can use a cloud temporarily, or at night a star.

Source: americanboating.org