Whether it's monohull, catamaran or trimaran basically categorized in 3 based on the type of hull form below the surface of the water line, yaitu Displacement hull, semi displacement hull/semi planning dan planning hull.
Displacement hull boat is moving on the surface of the water itself weighing boat (weight of water displaced as heavy boat), then to get the maximum speed of the submerged hull forms in the water from the front to the back is a streamlined, and the cross-section at the bottom of the water was made round. It is intended to reduce frictional resistance and wave resistance at the surface of the water speeding boats.
There is 2 macam tipe displacement hull, namely :
Heavy displacement : boats that are used for heavy work on the stern boat, like a tug boat and a boat deep sea trawlers.
Medium displacement : these boats are commonly used for this type of displacement hull or not to work pull heavy loads, seperti pleasure boats, fishing boats, sail boat, yachts and other.
Type displacement hull boats allocated to a low speed (froude number < 1.4).
Excellence Displacement hull is small engine power, so that fuel consumption is much lower. Small engines means the cost of buying and maintaining a lighter, besides these boats tend to be stable and comfortable while anchored to relax by the sea.
Type of planning hull boats are moving on the surface of the water at high speed so that the water displaced is not heavy boat body itself due in part to the front of the hull lifted, so the barrier below the surface of the water into a small.
With a high-speed course requires a large power, Great power requires great fuel consumption too, so the type of boat is arguably very expensive. In Indonesia, most types of boats are owned by the government and military for patrol needs, inspections and the like, As for the personal usually for the purposes of recreation and beach sports such as fishing boat, pleasure boat dan power boat.
Type of planning is that from year to year changes and significant progress for the world maritime.
A generic term for the type of planing we know is: Moderate V dan Deep V . Moderate V, at the transom deadrise angle ranges 15 degrees to 19 derajat. While Deep V, at the transom deadrise angle of 20 to 24 derajatdegree
Semi displacement hull/ Semi Planing
In the semi displacement / semi-planning hull with a maximum speed of the front can be lifted up, This depends on the value of Froude and hull shape itself.
To get a good speed / maximum with good stability usually in the V-shaped boat bow and at the stern shaped somewhat flat and there is also a rather round-shaped.
Sari three types mentioned above which have the best stability is the type of planning hull, because it has a point value of GM or large metacentric. But in terms of comfort of displacement type hull which has particularly best comfort.
Speed / length ratio or Froude number is known as one of the parameters that can be used as a consideration in choosing the type of hull that is appropriate for the needs of :
Length is the length of the waterline boat (Lwl)
For those who want to buy a motor boat there are a few tips that will make you not disappointed. Because the motor boats right (blend of speed comfort and stability) very expensive, while very difficult to resell.