Disambiguation

A weir /wɪər/, or low-head dam is a barrier across the width of a body of water that alters the flow characteristics of water and usually results in a change in the height of the water level. Weirs are used to control the flow of water for rivers, outlets of lakes, ponds, and reservoirs, industrial discharge, and drainage control structures. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. Weirs pose a serious danger to boaters and have been involved in several fatal drownings. Commonly, weirs are used to prevent flooding, measure water discharge,[3] and help render rivers more navigable by boat.



A body of water, such as a canal, lake, reservoirs, or river, is navigable if it is calm, deep, and wide enough for a watercraft (e.g. boats) to pass safely. Navigability is also referred to in the broader context of a body of water having sufficient under keel clearance for a vessel.[1]

In seafaring, under keel clearance (UKC) is the vertical distance between seabed and the keel or hull of a ship.[1][2][3]

Seamanship is the art, competence, and knowledge of operating a ship, boat or other craft on water.[1] The Oxford Dictionary states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea."[2]

Watchkeeping or watchstanding is the assignment of sailors to specific roles on a ship to operate it continuously.

A role (also rôle or social role) is a set of connected behaviors, rights, obligations, beliefs, and norms as conceptualized by people in a social situation. Competency is the state or quality of being adequately or well qualified, possessing the ability to perform a specific, measurable job. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning. In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading (or direction or course), and elapsed time.