A sailboat’s keel keeps the boat from being blown sideways, converting lateral forces of the wind to forward thrust. Weighted keels also provide ballast low in the water to resist the heeling force of wind sideways on the sails. Different sailboats have different kinds of keels.
The length of the keel (in a fore-aft direction) varies considerably among different types of sailboats. On one extreme is the traditional full keel, running much of the waterline length of the hull. At the other extreme is the contemporary narrow fin keel, swing keel, or centerboard.
Advantages of Full Keel Sailboats
A sailboat with a full keel tracks more easily through the water, moving forward with less swinging off course due to wind gusts and wave action. A full-keel boat generally also has a more sea-kindly motion.
Disadvantages of Full Keel Sailboats
Full-keel boats are slower to turn when the rudder is moved and may be difficult to tack (turn across the eye of the wind) in light wind. Because the larger surface area below the waterline causes more drag, full-keel boats are also usually somewhat slower than boats of the same size with a fin keel.