DICTIONARY OF

Green Flash 157 Grounding
Green Flash. Momentary flash of green light occasionally seen in horizon just after sunset,
or before sunrise, in clear atmosphere. Due to refraction of Sun's light.
Green Sea. Sea that sweeps over a vessel without breaking.
Greenwich Date. Time and date at Greenwich corresponding to an instant of time at another
position.
Greenwich Hour Angle. Intercepted arc of Equinoctial between hour circle at Greenwich
and hour circle at a given place, measured westerly.
Greenwich Mean Time. Time based on hour angle of point of definition of mean time as
measured at Greenwich.
Greenwich Meridian. Adopted as the prime, or International, meridian, largely because its
antemeridian - the Date Line - passes through no important land masses.
Gregale. N.E. gale in vicinity of Malta during winter. Name is also given to similar wind in
Tyrrhenian Sea and off S. Coast of France.
Gregorian Calendar. Reformed calendar introduced by Pope Gregory XIII in 1582.
Previous (Julian) calendar assumed year to be 365 ¼ days, which was 0.0065 of a day in
excess. Gregorian calendar will be in error by one day in A.D. 5442.
Gridiron. Horizontal, grated framework on to which a small vessel can be hauled for
examination and repair of bottom; grating being hauled up inclined ways until clear of water.
Gripe. The forward deadwood. Flat surface in way of forefoot of a sailing vessel. Designed
to make her more sensitive to helm, particularly when wearing, and to reduce leeway. 2.
Sennit strips by which a boat is prevented from swinging when suspended from davits at sea.
Also, length of wire or chain having a claw that fits over gunwale of boat and prevents
movement in the crutches when stowed inboard. 3. Resistance set up by gripe of forefoot,
causing vessel to lie closer to wind.
Griping. Coming too close to wind when under sail.
Grog. Mixture of rum and water. Named after Admiral Vernon, who first issued watered
rum. He was in the habit of wearing grogram breeches, and was nicknamed 'Old Grog'.
Grommet. Ring made of rope strand laid up around its own part.
Grooving. In a steel plate, is the formation of a narrow groove by corrosion.
Gross Pressure. Total pressure as differentiated from pressure that ignores atmospheric
pressure. Steam gauges of boilers indicate pressure in excess of atmospheric pressure.
Gross Tonnage. Measurement of total internal volume of a vessel and includes all under
deck tonnage and all enclosed spaces above tonnage deck; 100 cubic feet of space being
considered as one ton.
Groundage. Money paid by a vessel for occupying space in a port.
Grounding. Bringing vessel's keel into contact with the bottom so that she ceases to be
completely waterborne.