What Is the Scag on a Boat For?

A skeg or skag on a boat refers to the fixed extension of the sternward keel. In some boats, like kayaks, a keel may be retractable. In other boats, a skag may also refer to the motor itself. Skags are used on a variety of boats, including warships, kayaks and yachts.

  1. Steering Ability

    • Use of a skag improves the ability to steer the boat. The design of the skag strengthens the keel line to facilitate steering in windy conditions, especially on kayaks. The skag design focuses water flow over the hull and propellers, facilitating easier steering in turbulent waters.

    Improve Stability

    • On smaller vessels, waves breaking against the boat can render the vessel directionally unstable. The skag provides a stabilizing force by providing some resistance to the flow of water breaking on either the starboard (right) or port (left) sides of the boat. This allows the boat to maintain a forward direction rather than constantly moving sideways.

    Protect the Propeller and Shaft

    • On warships, the skag can deflect the blast from a torpedo downwards to protect the shaft. Use of skag on large vessels, such as tankers and aircraft carriers, protects the shaft from bending under the force of the water during high-speed turns. On all boats, the skag helps to protect the shaft, gear case and propellers from damage when crossing a stump, log, submerged rock or sandbar.

    Engine

    • For boats with external motors, the engine may be called the skag. The skag, in this case, is made of a single-unit engine and propeller. Below the propeller, a traditional skag may be part of the design to protect the propeller, but this is not always the case. The engine skag powers the propellers to drive the boat forward in the water.