SOUNDING DATUM - The plane to which vsoundings are referred o See also 

 DATUM, CHART, 



SOUNDING IINE - A line^ wire, or cord used in sounding. It is weighted 

 at one end with a plummet (sounding lead) « Also LEADLINE, 



SPILLING BREAKER - See under BREAKER c 



SPIT - A small point of land or submerged ridge running into a body of 

 water from the shore o (See Figure A-9) • 



SPRIN.G TIDE - A tide that occurs at or near the time of new and full 



moon and which rises highest and falls lowest from the mean level. 



STAND OF TIDE - An interval at high or low water .when there is no sensible 

 change in the height of the tideo The water level is stationary at 

 high and low water for only an instant, but the change in level near 

 these times is so slow that it is not usually perceptible. See 

 TIDE, SLACK. 



STANDING WAVE - A type of wave in which the surface of the water 



oscillates vertically between fixfed points, called nodes, without 

 progression. The points of maximum vertical rise and fall are called 

 antinodes or loops. At the nodes, the underlying water particles 

 exhibit no vertical motion but maximum horizontal motion. At the 

 antinodes the underlying water particles have no horizontal motion 

 and maximum vertical motion. They may be the result of two equal 

 progressive wave trains travelling through each other in opposite 

 directions,, Sometimes called STATIONARY WAVE. 



STATIONARY WAVE - A wave of essentially stable form which does not 



move with respect to a selected reference point| a fixed swelling. 

 Sometimes called STANDING WAVE. 



STILL WATER LEVEL - The elevation of the surface of the water if all wave 

 action were to cease. (See Figure A-3) 



STONE - (l) Rock or rocklike matter used as a material for building^ 

 (2) A small piece of rock or a specific piece of rock, 



STONE, ^DERRICK - Stone of a sufficient size as to require handling in 

 individual pieces by mechanical means, generally 1 ton up, 



STORM TIDE - The rise of water accompanying a storm caused by wind 

 stresses on the water surface. See also SET-UP, WIND. 



STRAIT - A relatively narrow waterway between two larger bodies of water. 

 See also SOUND (noun). 



A-33 



