English

The thin wavy line of fine SAND, mica scales, bits of SEAWEED, etc., left by the UPRUSH when it recedes from its upward limit of movement on the BEACH.

Any of a number of systems which are capable of obtaining a strip or lane of ELEVATIONs or SOUNDINGs from a single SURVEY PLATFORMS’s TRACK.  In HYDROGRAPHY, systems that fall into this category are MULTI BEAM ECHO SOUNDERs (MBES), INTERFEROMETRIC ECHO SOUNDERs and LIDAR.

(v.t. & i.). To tow a line or object below the surface, to determine the least depth in an area or to insure that a given area is free from navigational dangers to a certain depth; or the removal of such dangers.

The process of towing a line or object below the surface, to determine whether an area is free from isolated submerged dangers to vessels and to determine the position of any dangers that exist, or to determi­ne the least depth of an area.

Ocean waves which have travelled out of their generating area. Swell characteristically exhibits a more regular and longer PERIOD and has flatter CRESTS than WAVES within their FETCH. Rising of the water of a RIVER above its usual LEVEL. Gently rising GROUND or a rounded HILL above the surrounding GROUND.

The process of placing a vessel on various HEADINGS and compar­ing MAGNETIC COMPASS rea­dings with the corresponding magnetic DIRECTIONS, to determine DEVIATION. This usually follows COMPASS COMPENSATION (or ADJUSTMENT), and is done to obtain information for making a DEVIATION TABLE. Also called compass calibration, or calibration of compass. See COMPENSATION OF MAGNETIC COMPASS.

A CHARACTER, letter, or similar graphic repre­sen­tation used on a CHART, MAP, HYDROGRAPHIC SURVEY SHEET, or DIAGRAM to represent some object, quantity, charac­teristic, etc.

The interval of time between any planetary configuration of a CELESTIAL BODY, with respect to the SUN, and the next successive same configuration of that body, as from INFERIOR CONJUNCTION to INFERIOR CONJUNCTION.