consumption with increased engine power: Full-displacement hulls move the water up and out of the way of the vessel, making a wave. They are limited in speed by the square root of the waterline length multiplied by a factor, depending on the units used. Added horsepower cannot increase the maximum speed, only the size of the waves produced. Semi-displacement hulls allow speeds that are faster than the hull speed of a displacement vessel because they rise somewhat out of the water and create smaller waves. They also provide greater comfort than planing hulls. Planing hulls require sufficient power for the boat to slide up onto the surface, which avoids the need to use power to lift water out of the way of the vessel. Such vessels have flat surfaces on the undersides. A typical semi-displacement yacht has a wedge-shaped bow, which promotes penetrating waves, that transitions to flatter, wider surfaces aft, which promotes lifting the vessel out of the water—the "deep vee" hull, designed by Ray Hunt, found in approximately 75% of modern power boats. Cruising motor yachts are available in a range of styles as two-engine , ranging in length from with top speeds ranging from . Engines Motor yachts typically have one or more diesel engines. Gasoline-powered motors and engines are the provenance of outboard motors and racing boats, due to their power-to-weight ratios. Two engines adds expense, but provides reliability and maneuverability over a single engine. Motor yachts in the range might have the following hull, horsepower, cruise speed, and hourly fuel consumption characteristics: – two diesels to cruise at , consuming . – two diesels to cruise at , consuming . – two diesels to cruise at , consuming . Superyachts may employ multiple diesels or a combination of diesels and gas turbines with a combined . See also World Sailing List of keelboat classes designed before 1970 List of large sailing yachts List of motor yachts by length List of sailing boat types List of sailboat designers and manufacturers Model yachting Superyacht Yacht broker Yacht charter Yacht racing Yacht transport Yacht tender Yacht support vessel Yachting References External links Yachts Dutch inventions Ship designs of the Dutch Republic