Steering a boat is different from steering a car; moreover, it differs in three distinct and important ways. In a car, the front changes direction and the back follows the front around the curve. In a boat, the rudder kicks the back to one side or the other and the craft basically skids around the curve. The pivot point for a car is at the center of the front bumper. The pivot point for a boat might be well forward of the bow, if it is a powerful planing hull, or well aft of the bow for a sailboat.
Steerage Way
Like the steering in a car, a boat rudder has no effect if the boat is standing still. Unlike a car, however, the rudder has little effect at low speed and becomes increasingly effective as the boat moves faster. This speed, which allows the rudder to steer the boat, is called steerage way.Prop Walk
When in reverse, as the propeller moves the boat backward by pushing water forward, it also moves the stern somewhat sideways. This motion, called prop walk, tends to kick the stern to the left if the prop is right-handed, and therefore rotates clockwise as seen from astern, or to the right in the much less common case of a left-handed prop. It is most evident at high engine RPM when the boat has no steerage way on and is standing still or barely moving.Prop walk can be useful for turning the boat. This works only in reverse, however, and only when pivoting in the direction of the prop walk. On an unfamiliar boat, test for prop walk by revving the engine briefly in reverse, perhaps while still tied up at dock, and watching to see which way the stern moves. When prop walk is not wanted, reduce it by keeping engine RPM low, in reverse, until you have steerage way on.
Wheel
Steering
Wheel steering allows a helmsman to turn the rudder by rotating a wheel in the cockpit. It gives mechanical advantage, making a large rudder easier to control than it would be with a direct tiller. Turning the wheel moves a sprocket and chain inside the pedestal. The chain pulls cables routed through sheaves to a quadrant or radial wheel attached to the rudderstock. That quadrant rotates the rudderstock and rudder. The steering wheel is therefore only the visible control. The important parts of the steering system lie inside the pedestal and below the cockpit, where they must translate small movements at the helm into reliable control of a heavily loaded rudder.Usually controlled by a knob on the pedestal, a wheel brake uses friction to hold the wheel still temporarily. When applied while docked or at anchor, it keeps the rudder from swaying in wind or current. It is useful while motoring or briefly adjusting a sail, but it is not an autopilot and should not be used to compensate for poor sail balance.
A properly balanced sailboat needs only modest steering pressure. Wheel steering can hide heavy weather helm because of its mechanical advantage. Persistent force on the wheel is usually a sail-balance problem, not something to overcome with more muscle. Reducing heel by easing or reefing the mainsail and balancing the headsail can greatly reduce rudder load.
Autopilot
An autopilot can steer the boat—effortlessly, without much attention and better than any helmsman—on a straight course or even along a chain of waypoints. It can take over for a brief time, while the helmsman attends to something, or for hours while traversing a channel or canal. On a long passage inland, such as down the ICW, an autopilot is almost essential.Some autopilots attach to the steering wheel by means of a notched belt. Others attach to an arm on the rudder post by means of a hydraulic cylinder. Rudder post autopilots are much stronger, which means they can be used in heavier air, and they can also substitute for an emergency tiller. Autopilots that attach to the steering wheel take less power and are more suitable for smaller boats sailed mainly close to shore.
Many autopilots have buttons for making course changes of 10 degrees and one degree. When using the 1-degree button, click it always three times because three degrees is the least that you can discern while at the helm. There might also be a responsiveness setting that determines how sensitive the unit is to course changes. A high response setting makes the unit “steer small” by making frequent changes that can waste battery power. The lowest response setting is often the best, for sailboats, even when motoring.