Busan Regional Office of Oceans & Fisheries
Different types of the bottom structure include leeboard keel, centerboard keel, fin keel, bulb keel, heavy keel, twin keel and long keel. Leeboard keel is a yacht type with leeboards (resisting boards) installed at both sides of the yacht in order to resist leaning to the transverse direction due to external forces such as the tidal current or the wind. Centerboard keel is a yacht type with a centerboard that can be moved up and down by penetrating a keel (a bar stretched along the bottom of a yacht) in the middle of the hull. Fin keel is a type of yacht equipped with fixed heavy material of metal in a shape of a fin instead of a centerboard at the bottom of the hull. Heavy keel is a type of yacht with fixed heavy material in steel at the bottom of the yacht as a part of the hull. Generally, it is used for a large size yacht. Bulb keel is a transformed type of fin keel. The fin in the shape of thin plate makes up the ballast, and under the plate, a bulb in the shape of a bomb is attached on a bulb keel yacht. Twin keel is a type of yacht with two shortened fins installed obliquely toward the lower part of both sides in the middle of the hull. So, it can be approached to the land closely. Long keel is a type of yacht that the keel itself makes up a resisting body. It belongs to the typical kind of Western sailing boat.
Yachts classified by different types of the sail, i.e. mast, include cat, sloop, cutter, schooner, ketch and yawl. Cat yacht is a type with a relatively large sail with a single mast mounted near the bow. It is easy to operate and can sail in a fast speed so that this small-sized yacht is used for racing. It is also suitable for beginners learning how to sail. Sloop yacht is the most common type equipped with a jib (a triangular sail equipped in front of the mast) and main sail. The number of sails in the sloop yacht can be varied from two to more than five sails. The heights also can be different ranging from 3 to 30 meters. Cutter yacht is a type of sloop yacht equipped with gaff-topsail, jib-topsail, forestay, jib or main sail. Along with the sloop type, it represents the basic format of the modern yachts. Schooner yacht has more than two masts and this type is common among large-sized yachts. Yawl yacht is a type which places a higher priority on operation than speed and has a large hull with two masts. One feature of yawl type is that the rear mast is at the back of the rudder. Ketch yacht is a type which picked strong points of the yawl yacht. However, the rear mast is bigger compared to the yawl and is situated forward of the rudder.
In order to prevent the cross current leaning to the side when a yacht proceeds with the wind blowing from the side, a protruded device is installed at the bottom of the yacht. According to the types of these devices, yachts are classified as lee board, center board, dagger board, pivot board, fin keel and deep keel.