Chine
Knickspant is called the shape of a boat hull. If the formers do not have a round shape, as in the case of the round chine , but at least one kink, one speaks of a knickspanter. There are single chine, double or multi chine, such as B. the Waarship .
Sailing boats
Some chine boats have a flat bottom, such as the Optimist . Others have a pointed floor, like the OK dinghy . The round construction (round frame shape) is more common and more suitable for modern plastic construction.
In principle, the hard chine construction with a lower material thickness allows sufficient strength of the hull to be achieved. Furthermore, in the case of the chine, the kinks can take over the tasks of the longitudinal ribs, which leads to weight savings. The construction methods with GRP or with form-glued wood veneer have generally pushed the Knickspanter somewhat into the background, because the difficulties of the hull construction are no longer so decisive. Due to the kinks in the outer skin, knuckle chine has hydrodynamic disadvantages compared to other hull shapes. The hard chine construction was mainly based on the use of undeformed panels as building material (e.g. plywood or steel panels) and in some boat classes such as B. the optimist's desire to enable simple self-construction and thus to achieve wide distribution.
Other frame shapes common in sailing boats are various round frame or S-frame shapes.
Motor boats
In the case of fast motorboats, a kink usually results from the transition from the flat sliding surface on the bottom of the boat to the sides of the boat. With the help of the flattened bottom, the boat lifts out of the water at high speed and glides on the surface of the water. Straight surfaces are advantageous here, since they have less wetted surfaces than curved surfaces and thus reduce friction. Considerably higher speeds can be achieved in planing because of the reduced flow resistance, or lower drive power is required.
The disadvantage of such planing boats is the poor seaworthiness. If the speed is too high, there is an increased risk of the boat being damaged ( slamming ) due to the hard impact of the flat bottom on the waves . Rough seas or changes in direction too quickly can capsize the boat relatively easily.
In order to increase the seaworthiness of hard chine motor boats, a deep V is usually implemented in the bow area. This means that hard-chine inserts into the wave much more smoothly when the waves are rough. This also increases the seaworthiness because the boat goes more smoothly through the waves.
Examples of sailing boat classes with a hard chine construction
Cadet , Fireball , Kielzugvogel , OK-dinghy , Optimist , Pirate , Swordzugvogel , Starboot , Sunfish , Waarship .