Hull (watercraft)

The shape is chosen to strike a balance between cost, hydrostatic considerations (accommodation, load carrying, and stability), hydrodynamics (speed, power requirements, and motion and behavior in a seaway) and special considerations for the ship's role, such as the rounded bow of an icebreaker or the flat bottom of a landing craft.

In a typical modern steel ship, the hull will have watertight decks, and major transverse members called bulkheads.

In fiberglass or composite hulls, the structure may resemble wooden or steel vessels to some extent, or be of a monocoque arrangement.

In many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb, or other material.

Instead, its contours are interrupted by sharp angles where predominantly longitudinal panels of the hull meet.

Benefits of this type of hull include potentially lower production cost and a (usually) fairly flat bottom, making the boat faster at planing.

To counter the high drag, hull forms are narrow and sometimes severely tapered at bow and stern.

This produced maximum lift and a smooth, fast ride in flat water, but this hull form is easily unsettled in waves.

The flatter shape of a 6-degree hull will plane with less wind or a lower-horsepower engine but will pound more in waves.

They require more powerful engines to lift the boat onto the plane but give a faster, smoother ride in waves.

The advantage of the semi-round is that it is a nice middle between the S-bottom[clarification needed] and chined hull.

Typical examples of a semi-round bilge hull can be found in the Centaur and Laser sailing dinghies.

Since the early 1990s, a variety of commercial and freeware software packages specialized for naval architecture have been developed that provide 3D drafting capabilities combined with calculation modules for hydrostatics and hydrodynamics.