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Nautical mile: Length: Rhumb: Angle: The angle between two successive points of the thirty-two point compass (11 degrees 15 minutes) (rare) [1] Shackle: Length: Before 1949, 12.5 fathoms; later 15 fathoms. [2] Toise: Length: Toise was also used for measures of area and volume Twenty-foot equivalent unit or TEU: Volume: Used in connection with ...
A nautical chart will always explicitly indicate the units of depth used. [17] To measure the depth of shallow waters, boatmen used a sounding line containing fathom points, some marked and others in between, called deeps, unmarked but estimated by the user. [18]
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography. Soundings were traditionally shown on nautical charts in fathoms and
Used mainly to determine the minimum water depth for safe passage of a vessel and to calculate the vessel's displacement (obtained from ship's stability tables) so as to determine the mass of cargo on board. Draft, Air – Air Draft/Draught is the distance from the water line to the highest point on a ship (including antennas) while it is ...
UKC = Charted Depth − Draft-/+ Height of Tide. Ship masters and deck officers can obtain the depth of water from Electronic navigational charts. [5] More dynamic or advanced calculations include safety margins for manoeuvring effects and squat. [7] Computer systems and software can be used to manage and calculate UKC for ships and ports.
Today electronic computers or calculators are used. Other traditional aids used included tables (trigonometric, logarithms, etc.) and slide rules. Dividers used for measuring lengths of lines and approximate lengths of non-linear paths on a chart. Nautical almanac used to determine the position in the sky of a celestial body after a sight has ...
Tide tables give the height of the tide above a chart datum making it feasible to calculate the depth of water at a given point and at a given time by adding the charted depth to the height of the tide. One may calculate whether an area that dries is under water by subtracting the drying height from the [given] height calculated from the tide ...
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water . It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; the resulting time of flight , along with knowledge of the speed of sound in water, allows determining the distance ...