FIRTH . A long, narrow arm of the sea. Also called 

 frith. (17) 



FISH LEAD . A type of sounding lead used without 

 removal from the water between soundings. (17) 



FISH NET BUOY . A buoy marking the limit of a fish 

 net area. (17) 



FISSION . 1. The division of a unicellular organ- 

 ism into two equal daughter cells. (18) 



2. The disintegration of an atomic 

 nucleus which may happen from spontaneous causes 

 or more commonly when the nucleus itself is struck 

 by sub-nuclear particles, such as a neutron. As 

 the nucleus of an atom of uranium 235 is struck by 

 a neutron it may be absorbed, then immediately or 

 shortly after, the nucleus becomes unstable and 

 breaks, usually into two fragments. This fission 

 causes the release of other neutrons and of energy 

 in the form of radiation and heat. (39) 



FIXED ACOUSTIC BUOY (FAB) . The Fixed Acoustic Buoy 

 is a deep sea instrumentation device which measures 

 acoustic data at a depth of 14,000 feet. It is 

 controlled and powered from shore via a cable and 

 has numerous modes of operation. Signal processing 

 is accomplished in the deep sea unit to allow use 

 of a single coaxial cable. 



In FAB almost all of the signal processing is 

 accomplished electronically in the deep sea portion. 

 This results in a considerable cost saving because 

 it allows use of a single coaxial cable with medium 

 bandwidth requirements instead of 21 pair medium 

 bandwidth cable or one high bandwidth coaxial cable 

 with 21 channel multiplexing. (35) 



FIXED TIDE STAFF. See TIDE STAFF. 



FJORD (FIORD) . A long narrow arm of the sea be- 

 tween highlands . (11) 



FLAGELLUM . A long lash or threadlike extension 

 capable of vibration; on flagellate protozoans and 

 on collar cells of sponges. (19) 



FLAT ROPE. See WIRE ROPE, 



FLEXURAL MODULUS OF ELASTICITY . The Modulus of 



Elasticity of a material in the Flexure Test. It 



may be calculated from a Load-Deflection Diagram 



as follows: 



L /PV 

 Ef = V /— 1 (for rectangular specimen) 



(^\ (for round specimen) 



FLIPPERS. 



See SWIM FINS. 



0.425 l3 /p\ 



d4 

 where Ep = Flexural Modulus of Elasticity, psi 



Z = slope of initial straightline portion of 



curve on Load-Deflection Diagram, 

 lb/in. 

 Span, in. 

 Specimen width, in. (41) 



FLIP . A manned spar buoy, used free-floating with 

 long axis vertical, but also capable of a horizon- 

 tal, shallow-draft position used for berthing and 

 towing to and from station. The general purpose of 

 the structure is to provide a stable, acoustically 

 quiet platform to support hydrophones and other 

 instruments for making measurements under the sea 

 surface, and at the same time to enable measure- 

 ments at or above the surface. 



The total length of the structure is 355 ft, 

 of which 300 ft is normally submerged . 



The circular cross -section has a maximum 

 diameter of 20 ft, which diminishes to 12.5 ft in 

 the range from 75 ft depth to 15 ft above the water- 

 line, where the hull joins a superstructure having 

 a further height of 40 ft. (35) 



FLOATING ACCELEROMETER . This instrument for measur- 

 ing waves in the open sea utilizes an accelerometer 

 placed on a small raft which is connected with a 

 ship by a conducting cable. The accelerometer sup- 

 plies a signal which corresponds essentially to the 

 vertical acceleration of the sea surface. This sig- 

 nal is integrated twice, and the integrated record- 

 ing is made aboard ship. The frequency response 

 is constant to periods as small as 1.5 seconds. 

 The recorder has some of the disadvantages of the 

 WAVE STAFF in that it is a floating instrument and 

 thus tends to float away with the current. (35) 



FLOATING DOCK . See DOCK. 



FLOATING ICE . See FAST ICE. 



FLOCCULENT DEPOSIT . An aggregate or precipitate 

 of small lumps formed by precipitation. (27) 



FLOE . Sea ice, either 

 many individual pieces, 

 A small floe is 30 feet 

 medium floe, 600 feet t 

 floe, 3,000 feet to 5 m 

 more than 5 miles acros 

 posed of HUMMOCKED ICE 

 ice which has broken ad 

 a floe strong enough to 

 called sludge floe. Se' 



a single unbroken piece or 

 covering an area of water, 

 to 600 feet across; a 

 o 3,000 feet across; a giant 

 iles across; an ice field, 

 s. A huramocky floe is com- 

 A land floe is thick fast 

 rift. Sludge hardened into 



bear the weight of a man is 

 e GLACON. (17) 



FLOEBERG . A mass of thick, heavily-hummocked SEA 

 ICE resembling an ICEBERG in appearance. 



Floebergs may be from several feet to more 

 than fifty feet in height. An iceberg in its last 

 stages of disintegration may be mistaken for a 

 floeberg. (25) 



FLOOD CURRENT . The movement of a tidal current 

 toward the shore or up a tidal stream. In the 

 semidiurnal type of reversing current, the terms 

 greater flood and lesser flood are applied respec- 

 tively to the flood currents of greater and lesser 

 velocity of each day. The terms maximum flood and 

 minimum flood, are applied to the maximum and mini- 

 mum velocities of a flood current the velocity of 

 which alternately increases and decreases without 

 coming to a slack or reversing. (14) 



FLOOD INTERVAL . The interval between the transit 

 of the moon over the meridian of a place and the 

 time of the following strength of flood. (14) 



FLOOR (OCEAN FLOOR) . Used by some authors to 

 designate the bottoms of the deeper parts of the 

 oceans only, beyond the continental slope. Other 

 authors use it to refer to any part of the ocean 

 bottom. (27) 



FLORESCENCE . The rapid reproduction of plankton. 

 See PLANKTON BLOOM. (15) 



FLORIDA CURRENT . All of the northward -moving 

 water from the Straits of Florida to a point off 

 Cape Hatteras where the current ceases to follow 

 the continental slope. It is one of the swiftest 

 of ocean currents (flowing at a rate of 2 to 5 

 knots) . 



The Florida current can be traced directly 

 back to the Yucatan Channel because the greater 

 part of the water flowing through that channel 

 continues on the shortest route to the Straits of 

 Florida and only a small amount sweeps into the 

 Gulf of Mexico, later to join the Florida current. 

 After passing the Straits of Florida the current 

 is reinforced by the Antilles current, but the 

 name Florida Current is retained as far as Cape 

 Hatteras . 



The Florida current is part of the Gulf Stream 

 system. (24) 



FLOTSAM. See JETTISON. 



1*7 



