This glossary describes the key words and abbreviations used in this manual.

The angle measured in the plane of the water plane, between the hull and the centreline.

The wetted area of appendages, used to calculate appendage drag. Set this to zero to ignore appendage resistance.

A nominal length used to calculate the Reynolds Number of the appendages and hence the appropriate skin friction coefficient

A factor for estimating the resistance due to the drag on appendages. Expected values range from 1.0 to 3.0.

The maximum submerged width of the hull.

The distance from the keel line, to the transverse centre of area of the bulb section on the waterline at the stem.

The transverse sectional area of the bulb (if any) measured on the waterline at the stem.

A factor for accounting for variations between model tests and full-scale trials.

The angle measured in the section plane between the hull and the horizontal, as measured at midships.

The air density, at the appropriate ambient temperature. The default value is 1.293 kg/m^3 for air at 15°C.

The sea density, at the appropriate ambient temperature and salinity. The ITTC 1967 value, for salt water (3.5% salinity) at 15°C., of 1025.9 kg/m^3 is given as the default.

The volume of seawater displaced by the hull.

The maximum submerged depth of the hull. Sometimes also referred to as “draught”.

The draft at the fore perpendicular. This value can be left at zero, whereupon Hullspeed will assume it is the same as the value for the ‘draft’ item.

The coefficient of drag for calculation of wind resistance. Expected values would be in the range of 0.8 - 1.2.

The efficiency used to calculate the ship’s power from its resistance.

The area of the vessel above the waterline, when viewed from the front. Set to zero to ignore wind resistance.

A dimensionless speed measurement:

Length, L, is typically used, but may be inappropriate for some measurements, such as for a planing hull, where the waterline length varies with speed. In such circumstances, beam may be substituted for length, as may draft etc.

The kinematic viscosity of sea water. The ITTC 1967 value, for salt water (3.5% salinity) at 15°C., of 1.18831x10^-6 m^2/s is given as the default.

The distance to the longitudinal centre of gravity, measured from midships. Note that this distance is positive forward. That is, an LCG 1.5m aft of midships will be entered as -1.5.

The length of the hull, measured on the waterline.

The largest submerged sectional area of the hull, measured when the vessel is at rest.

A measure of the extent to which the submerged volume of a hull fills the prism defined by the submerged length, multiplied by the area of the largest transverse section.

The submerged sectional area of the transom, measured when the vessel is at rest.

The maximum submerged width of the transom.

The maximum submerged depth of the transom.

A measure of the extent to which the area of the water plane fills the rectangle defined by the length * beam.

The submerged surface area of the hull. For the slender body method, the wetted area is used to calculate the Friction and Viscous resistance coefficients only; the wave resistance is calculated directly from the surface model.

The wetted area is also used to calculate the resistance coefficients displayed in the Graph window.

A dimensionless speed measurement based on the cube-root of the displaced volume.