What is the primary use of the keel in ship design?

The primary use of the keel in ship design is to ensure stability. The keel serves as the backbone of the ship, extending along the bottom from the bow to the stern, providing structural support and helping to distribute weight evenly. By lowering the center of gravity and increasing the waterplane area, the keel plays a crucial role in preventing excessive rolling and capsizing in rough waters. This stability is essential for maintaining balance and operational safety, particularly in turbulent conditions.

While the other aspects mentioned—lift, speed, and maneuvering—are important considerations in overall ship performance, they do not capture the primary function of the keel. The keel does contribute to lift in certain designs, particularly in sailing vessels, but its most critical role remains that of maintaining stability.