BAY ICE . Young, flat ice of sufficient thickness 



to impede navigation. In the antarctic this term 



also has been used at times for heavy LAND FLOES. 

 (25) 



BAYOU . A minor, sluggish waterway or estuarial 

 creek, generally tidal or with a slow or impercep- 

 tible current, and with its course generally 

 through lowlands or swamps, tributary to or connect- 

 ing with other bodies of water. Various specific 

 meanings have been implied in different parts of 

 the southern United States. Sometimes called 

 slough. (17) 



BB . U. S. Navy designation for a Battleship. 



BCF . Bureau of Commercial Fisheries. 



BDHI . Bearing Distance Heading Indicator. 



BDI . Bearing Deviation Indicator (on ASW gear) . 



BEACH . (1) The zone of unconsolidated material 

 that extends landward from the low water line to 

 the place where there is marked change in material 

 or physiographic form. . . or to the line of perma- 

 nent vegetation (usually the effective limit of 

 storm waves). The seaward limit of the beach - 

 unless otherwise specified - is the mean low water 

 line. A beach includes FORESHORE and BACKSHORE. 

 (2) Sometimes, the material which is more or less 

 in active transport, alongshore or on-and-off 

 shore, rather than the zone. (11) 



BEACH BERM . A nearly horizontal portion of the 

 beach or backshore formed by the deposit of mate- 

 rial by wave action. Some beaches have no berms, 

 others have one or several, (10) 



BEACHCOMBER . A long, curling wave. Also called 

 comber. (17) 



BEACH CUSP . See CUSP. 



BEACH EROSION BOARD STEP-RESISTANCE GAUGE . This is 

 a fixed wave gauge which utilizes a 25-foot length 

 of sealed pipe housing a series of electrical con- 

 tact points spaced at intervals of 0.2 foot. The 

 contact points (made from spark plugs) are connected 

 to a resistance circuit within the pipe. The gauge 

 is mounted vertically on a supporting structure, 

 such as a pier, and the bottom of gauge is set 

 below the lowest expected wave trough. (The top of 

 the gauge must be above the highest expected wave 

 crest.) The exposed tips of the plugs are covered 

 with lead to reduce corrosion effects. In order 

 to overcome the short-circuiting effects of the 

 sea water film which adheres after a wave passes, 

 the gauge pipe and the bases of the spark plugs are 

 covered with neoprene. (35) 



BEACH FACE . The section of the beach normally 

 exposed to the action of the wave uprush. The 

 FORESHORE zone of a BEACH. (10) 



BEACH, FEEDER . An artificially widened beach serv- 

 ing to nourish downdrift beaches by natural littoral 

 currents or forces. (11) 



BEACH PROFILE . The intersection of the ground sur- 

 face with a vertical plane; may extend from the top 

 of the dune line to the seaward limit of sand move- 

 ment. (11) 



BEACH RIDGE . An essentially continuous mound of 

 beach material behind the beach that has been 

 heaped up by wave or other action. Ridges may oc- 

 cur singly or as a series of approximately parallel 

 deposits. In England they are called fulls. (11) 



BEACH SCARF . An almost vertical slope along the 

 beach caused by erosion by wave action. It may 

 vary in height from a few inches to several feet. 



depending on wave action and the nature and composi- 

 tion of the beach. (11) 



BEACH WIDTH . The horizontal dimension of the beach 

 as measured normal to the shore line. (11) 



BEAM PATTERN . See DIRECTIONAL RESPONSE PATTERN. 



BEAM SEA . Waves moving in a direction approximately 

 90" from the heading. Those moving in a direction 

 approximately opposite to the heading are called 

 HEAD SEA, those moving in the general direction of 

 the heading are called FOLLOWING SEA, and those 

 moving in a direction approximately 45 from the 

 heading (striking the quarter) are called QUARTERING 

 SEA. See CROSS SEA. (17) 



BEAM TIDE . A tidal current setting in a direction 

 approximately 90° from the heading of a vessel. 

 One setting in a direction approximately 90° from 

 the course is called a cross tide. In common usage 

 these two expressions are usually used synonymously. 

 One setting in a direction approximately opposite 

 to the heading is called a head tide. One setting 

 in such a direction as to increase the speed of a 

 vessel is called a fair tide. (17) 



BEAM WIDTH . The beam width of a directional 

 transducer at a given frequency in a given plane 

 including the beam axis, is the angle included 

 between the two directions, one to the left and 

 the other to the right of the axis , at which the 

 angular deviation loss has a specified value. 

 Typical values that are used in the specification 

 ai'e losses of 3, 6, or 10 decibels. (9) 



BEARING RATE . Rate of change of bearing. (7) 



BEATS. Beats are periodic variations that result 

 from the superposition of two simple harmonic 

 quantities of different frequencies. They involve 

 a periodic increase and decrease of amplitude at 

 the beat frequency which is equal to the difference 

 in the frequencies of the two parent signals. Thus, 

 if two pure tones having frequencies of 300 and 

 400 cycles per second are heard by a listener, 

 then he will also sense a frequency equal to the 

 difference, namely 100 cycles per second. This is 

 a beat frequency. (9) 



BEAUFORT WIND SCALE . A system of estimating and 

 reporting wind speeds. Invented in the early nine- 

 teenth century by Admiral Beaufort of the British 

 Navy. It was originally based on the. effects of 

 various wind speeds on the amount of canvas that a 

 full-rigged frigate of the period could carry, but 

 has since been modified and modernized. In its 

 present form for international meteorological use 

 it equates (a) Beaufort force (or Beaufort number) , 

 (b) wind speed, (c) descriptive term, and (d) 

 visible effects upon land object or sea surface. 

 (24) 



"BEAVER". A manned submersible vehicle (US). 



BED. The ground upon which a body of water rests. 

 The term is usually used with a modifier to indi- 

 cate the type of water body, as river bed. (17) 



BEL . The bel is a unit of level when the base of 

 the logarithm is 10. Use of the bel is restricted 

 to level of quantities proportional to power. (1) 



BELAT . A strong land wind from the north or north- 

 west which sometimes blows across the southeastern 

 coast of Arabia, and is accompanied by a hazy at- 

 mosphere due to sand blown from the interior desert. 

 (17) 



BELL BUOY . A buoy equipped with a bell. In United 



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