By: Captain Bill Jennings
Road vehicles steer with the two front wheels. When you go around a corner, you are aware that the back of the vehicle follows a path on the inside of the curve. In other words, if you steer around a corner with the front wheels close to the curb, your back wheels will run over the curb. Because boats steer differently than cars, most first time boaters have a little difficulty catching on to close quarter steering.
Power boats with stern steering have what is called a "pivot point." This point is usually located one third aft of the total boat length, measured from the bow. Because the steering action is applied at the stern of the boat (unlike the front wheels on a car), the propeller initiates the turn by pushing the stern out and in the opposite direction of the turn you are making. But at the same time your new heading points in the direction you desire, so the turn is accomplished and your stern follows around in the new direction. You need to be aware of this pivot point in boats when turning. With the pivot point located where it is, when you turn your boat left, your stern will swing right, outside the turning circle made by the pivot point and you are in danger of having the stern of your boat clip an object on your right. Vice-versa when you turn right. In summary, on a car, your rear end follows inside the arc you steer but on a boat, the rear end follow to the outside of the arc you steer. Therefore, when maneuvering in close quarters it is important to leave sufficient space on the outside of your turn to make the turn safely. Remembering that your pivot point is one third aft from the bow will help you anticipate your turning radius and maneuver accordingly.
There is one more thing you should know about the pivot point in your power boat. When you are backing up, the pivot point moves aft to one third of the boat length from the stern. So when backing out of a slip, be careful not to turn too soon, or your bow that will be swinging outside your pivot point could strike the dock.
Understanding your "pivot point" can eliminate much grief around other boats and when docking.