CURRENT TABLES 



HOURS 

 2 4 6 8 10 12 U 16 18 20 22 24 



§0 



St 



I M I M M I M M M M M M M 



-3- 



T \ 



f 



!l I I I ^ ' ^TT 



w - 



2 



1. Flood strength; 2. Ebb strength; 3. Slock water; 

 4. Greater ebb; 5. Greoter flood; 6. Lesser ebb; 

 7. Lesser flood 



CURRENT CURVE 



phase of the current at a reference station for 

 Avhich predictions are given in current tables. 

 (50) 



current direction — The direction toward which 

 a current is flowing, called the set of the current. 

 (68) 



current ellipse — A graphic representation of a 

 rotary current in which the speed and direction 

 of the cui-rent at different hours of the tide cycle 

 are represented by radius vectors and vectorial 

 angles. A line joining the extremities of the 

 radiiis vectore will fonn a curve roughly ap- 

 proximating an ellipse. 



current gradient — The rate of increase or de- 

 crease in the speed of a current relative to a given 

 distance or period of time. The gradient is 

 generally reiDresented by a curve. 



current hour — The mean interval between the 

 transit of the moon over a reference meridian 

 (usually Greenwich) and the time of the 

 strength of flood current modified by the times 

 of slack water and strength of ebb current. 



current meter — Any one of numerous devices for 

 the measurement of either speed alone or of both 

 direction and speed (set and drift) in flowing 

 water. (5) 



current pattern — The horizontal distribution of 

 the surface or subsurface currents at various 

 levels in a specified area. 



current pole — A pole used in measuring surface 

 water current, especially from an anchoi-ed ship 

 such as a lightship. The drift of the pole is 

 timed as it is allowed to carry out a graduated 



line, the azimuth and speed of the line gives the 

 current velocity. (5) 



current profile — A graphic presentation of cur- 

 rent flow from tlie surface to a specified depth. 

 Tlie speed of tlie current is generally represented 

 by the abscissa and the depth by the ordinate 

 which increases from the surface (zero) down- 

 ward. See current cross section. 



current rips — Small waves formed on the sea 

 surface by the meeting of opposing currents. 



current rose — A graphic presentation of currents 

 for specified areas, utilizing arrows at the cardi- 

 nal and intercardinal compass points to show 

 the direction toward which the prevailing cur- 

 rent flows and the percent frequency of set for 

 a given period of time. The arrows on some 

 presentations may be further subdivided (by 

 thickness or pattern) to designate categories of 

 current speeds. 



current speed — The rate at which the water moves 

 either horizontally or vertically ; usually ex- 

 pressed in knots, miles per day, feet per second, 

 or centimeters per second. See current 

 velocity. 



current tables — Tables which give daily predic- 

 tions of the times, speeds, and directions of the 

 currents. These predictions are usually supple- 

 mented by current differences and constants 

 by means of which additional predictions can be 

 obtained for numerous other places. (50) 



NORTH 



n 



L + 3 

 L + 2 ^ 0-~. 



/ 



/ 

 L + 1 O 



/\ 

 / 



^H-2 

 / \ 



/ b-", 



/ 





/ 



l6 

 / 



L-1 



L-2'c/ 



c3h + 



QH 



.^/ 



/ 

 / 



OH + 2 



— o— - 



H + 3 



I I I 1 I I 



0.0 0.2 0.4 0.6 8 1.0 

 SCALE (KNOTS) 



CURRENT ELLIPSE 



207-109 O— 66- 



43 



