VelocityVelocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector quantity, meaning that both magnitude and direction are needed to define it (velocity vector).
Relative velocityThe relative velocity of an object B with respect to an observer A, denoted vB∣A{\displaystyle \mathbf {v} _{B\mid A}} (also vBA{\displaystyle \mathbf {v} _{BA}} or vBrelA{\displaystyle \mathbf {v} _{B\operatorname {rel} A}}), is the velocityvector of B measured in the rest frame of A. The relative speed is the vector norm of the relative velocity, vB∣A=‖vB∣A‖{\displaystyle v_{B\mid A}=\|\mathbf {v} _{B\mid A}\|}.
Point of sailA point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. For many sailing craft 45° on either side of the wind is a no-go zone, where a sail is unable to mobilize power from the wind.
AnemometerIn meteorology, an anemometer (from Ancient Greek (ánemos)'wind' and (métron)'measure') is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti (1404–1472) in 1450. HistoryThe anemometer has changed little since its development in the 15th century. Alberti is said to have invented it around 1450.
SailingPropulsion of a vehicle by wind powerSailing craft and their rigsSloops racing with fore-and-aft sailsThree-masted barque with square sailsSailing hydrofoilcatamaran with wingsailDN classice boatClass 3 competition land yachtSailing employs the wind—acting on sails, wing sails or kites—to propel a craft on the surface of the water (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ice (iceboat) or on land (land yacht) over a chosen course, which is often part of a larger plan of navigation.
Degree (angle)A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a unit of measurement of a planeangle in which one full rotation is assigned the value of 360 degrees. The unit of angular measure in the International System of Units (SI) is the radian, and one degree is equivalent to π/180 radians. HistoryThe original motivation for choosing the degree as a unit of rotations and angles is unknown.
Knot (unit)The knot () is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s). The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization (ICAO). The knot is a non-SI unit.
Additive inverseIn mathematics, the additive inverse of an elementx, denoted −x, is the element that when added to x, yields the additive identity. This additive identity is often the number 0 (zero), but it can also refer to a more generalized zero element. In elementary mathematics, the additive inverse is often referred to as the opposite number, or the negative of a number.
MultihullA multihull is a boat or ship with more than one hull, whereas a vessel with a single hull is a monohull. The most common multihulls are catamarans (with two hulls), and trimarans (with three hulls). There are other types, with four or more hulls, but such examples are very rare and tend to be specialised for particular functions.
WindWind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hours, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The study of wind is known as anemology.
Euclidean vectorGeometric object that has length and directionA vector a→{\textstyle {\stackrel { ightarrow }{a}}} pointing from point A to point BIn mathematics, physics, and engineering, a Euclidean vector or simply a vector (sometimes called a geometric vector or spatial vector) is a geometric object that has magnitude (or length) and direction. Euclidean vectors can be added and scaled to form a vector space.Glossary of nautical terms (A–L)This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".*As an Amazon Associate I earn from qualifying purchases.