FRAM (FLERT REHABILITATION AND MODERNIZATION 

 PROGRAM . The purpose of the FRAM has been to 

 arrest the downward trend of material readiness 

 of the fleet, and to extend the life of certain 

 Navy ships . 



FRAUTSCHY BOTTLES . This water sampling device is 

 messenger actuated. It is designed to allow free 

 flow while in the cocked position on the downward 

 traverse. VJhen the desired sampling point has 

 been reached, the closures are messenger actuated, 

 resulting in isolation of the sample on the return 

 traverse. Frautschy Bottles may be attached to 

 the hydrographic wire at intervals and in such a 

 manner that release of a single messenger from the 

 surface will actuate the entire series. In this 

 way samples from several depths may be obtained in 

 a single operation. (30) 



FRB. 



Fisheries Research Board. 



a ship, the distance from the water line to main 

 deck or gunwale. (11) 



FREQUENCY . The frequency of a periodic function is 

 the reciprocal of the period. This is usually 

 given in cycles per second, but not always. For 

 example, the frequency of rotation of a propeller 

 shaft is often given in revolutions per minute. (9) 



FREQUENCY BAND . Those components of a complex 

 wave, the frequencies of which are included between 

 two points on a frequency scale. Such a limited 

 group of components is said to occupy a frequency 

 band. (4) 



FRINGING REEF . A reef attached to an insular or 

 continental shore. (11) 



FRONT OF THE FETCH . In wave forecasting it is that 

 end of the generating area toward which the wind is 

 blowing. (11) 



FREE ASCENT . When a diver or swimmer's air supply 

 fails or runs out, an emergency ascent becomes 

 necessary. The ideal method for making an emergency 

 ascent is accomplished by floating to the surface 

 by means of natural buoyancy or assisted buoyancy 

 from a lifejacket. While ascending with no life- 

 jacket, air is exhaled continuously at such a rate 

 that buoyancy is maintained, but the exhalation is 

 sufficient to prevent overexpansion of the lungs. 

 Free ascent, as this procedure is termed, is diffi- 

 cult for the untrained individual. 



Ascent assisted by an external source of 

 buoyancy (now termed BUOYANT ASCENT) requires a 

 slightly different technique. A fully inflated 

 lifejacket will cause a much more rapid ascent 

 through the water. The rate of ascent may be as 

 much as 400 feet per minute. With this method, 

 exhalation should start before ascent begins and 

 must be rapid and continuous in order to prevent 

 overexpansion of the lungs. (37) 



FREE ADMITTANCE . The free admittance of a trans- 

 ducer is the reciprocal of its blocked impedance. 

 (4) 



FREE FIELD . (See FREE SOUND FIELD) . 



FREE FIELD VOLTAGE RESPONSE . (See AS) . 



FREE IMPEDANCE . The free impedance of a transducer 

 is its input impedance when its load terminals are 

 short-circuited. (4) 



FREE INSTRUMENTS . A catagory of instruments that 

 are designed to initially sink to the bottom, re- 

 lease their heavy ballast weights, and then float 

 back to the surface where they can be retrieved 

 with their acquired payload (e.g. a sediment core). 



FREE PROGRESSIVE WAVE (FREE WAVE) . A free progres- 

 sive wave is a wave in a medium free from boundary 

 effects. That is, there are no reflections from 

 any nearby surfaces. A free wave can only be ap- 

 proximated in practice. (9) 



FREE-SOUM) FIELD . A free-sound field is a field 

 in a homogeneous, isotropic medium free from 

 boundaries. In practice it is a field in which 

 the effects of the boundaries are negligible over 

 the region of interest. (1) 



FREE WAVE . A wave representing one of the possible 

 oscillations of a body of water if this body is 

 set in motion by a sudden impulse. The period of 

 a free wave depends on the dimensions of the basin 

 and on the effect of friction. 



FREEBOARD . The additional height of a structure 

 above design high water level to prevent overflow. 

 Also, at a given time the vertical distance between 

 the water level and the top of the structure. On 



FROST SMOKE . A thick fog rising from the sea sur- 

 face when relatively warm water is exposed to an 

 air temperature much below freezing. Frost smoke 

 frequently appears over newly-formed CRACKS and 

 LEADS. If, however, the cold air moves across the 

 sea surface with a rush - that is, as a strong 

 wind - no fog is produced, as the vapor is distri- 

 buted by the accompanying turbulence through too 

 large a volume to produce saturation. (25) 



FRUSTULE . (1) The siliceous shell of a diatom com- 

 posed of two valves that overlap. (2) The sili- 

 ceous shell of a diatom together with the proto- 

 plast. (20) 



FRV. 



Fisheries Research Vessel. 



FSK . Frequency Shift Keyed. 



FUCOXANTHIN ■ A brown crystalline carotenoid pig- 

 ment C^Q HgQ Og occurring especially in the ova 

 of brown algae. (20) 



FUCUS (ROCKWEED) . Any of a genus of olive-green 

 or brown algae. Fucus grows attached to rocks; 

 hence, the name rockweed. (16) 



FULLS. See BEACH RIDGE. 



FULLY-DEVELOPED SEA (FULLY-ARISEN SEA) . The maxi- 

 mum ocean waves that can be produced by a given 

 wind force blowing over sufficient fetch, regard- 

 less of DURATION. All possible wave components 

 in the energy spectrum between f = and f = oo 

 are present with their maximum amount of spectral 

 energy. (12) 



FUMULUS . A very thin cloud veil at any level so 

 delicate that it may be almost invisible. (17) 



FUNDAMENTAL FREQUENCY . (1) The fundamental fre- 

 quency of a periodic quantity is the frequency of 

 a sinusoidal quantity which has the same period as 

 the periodic quantity. (2) The fundamental fre- 

 quency of an oscillating system is the lowest 

 natural frequency. The normal mode of vibration 

 associated with this frequency is known as the fun- 

 damental mode. (2) 



FUNDAMENTAL MODE OF VIBRATION . The fundamental mode 

 of vibration of a system is that mode having the 

 lowest natural frequency. (9) 



FURROW . A fissure which penetrates into a conti- 

 nental or insular shelf in a direction more or less 

 perpendicular to a coast line. (17) 



FWS . Fish and Wildlife Service (Department of 

 Interior) . 



FY. Fiscal year. 



1*9 



