56 
MANUAL OF CURRENT OBSERVATIONS 
Form 451 
Rev. Sept., 1931 
DEPARTMENT OF COMMERCE 
U. S. COAST AND GEODETIC SURVEY 
CURRENTS: FLOOD, EBB, AND SLACK 
Lat, 41° 23.4!N 
Station: Edgartown Harbor (0.3 mi, S 77° E of Church Tower), Masse Long.70° 30.5°W 
Acc. No. __T=2114 _ Party of E. Fe Hicks, Jre Plotted on Chart No. 1209 _ Station No. 19 
Times referred top Tides at Boston (Commonwealth Piers), Masse Time Meridians: (This Sta.) 75° W 
Velocities corrected for eee cane at Boston, Masse f = 9.40/11.33 = 0.83 2 “ (Ref. Stas) ae oe 
DATE TIME OF— | CURRENT INTERVALS Sak Ok FORK 2A OE ZARB 
Year | HW., LW. [cua Suensth | ci | Suen | Steck | Suengih | Gree | Strensth | Direct | Yociy | Dims | Vetoci 
193. Betmere | ot fiee | Beloit | oetsbe | Deterefe | ciiteed . | oeiahie |heg. Truc al be pe Uy 
mo. d h. Msp ee | INS | ae h. he eae knots | kfote | knots 
(1st) |(min.)(2na) (1st) | | (1st) (min,)| (2nd 
Lw Lood |Period eA MeL ees 
4 | --- | (7.2)|10.1 | 12.0] --- | 108 | 40.7 | 6.6 | 258 0.0 | 0,8 
17.9 |18.2 |19.6 | 22.2 | ---| 0.3 | 1-7 | 403 | --- | 244 | 1.5|-0.1 | --- 
25 | 602 6e8 | 8.0 |10.2 | 0.3] O38 | 168 | 4.0 | 6.4 | 244 | 1.6/-0.2 | 0.8 
[18.7 |19.1 | 20.5 | 2525 | 1205] 0.4 | 126 | 4.8 | 6.3 | 251 | 1.4 |-0,1 | 0.9 
Pole 26 | 7.0 | 7.2 | 868 |11.5| 10| 0.2 | 1.8 | 405 | 6.3 | 253 | 1.4 l-o2 | on 
Average |19,5 POL abe ee aa a aa 
pesos 27 [oa 8.0 | --- | 0.5 | 2.0] 0.3 | --- | 5,0 | 6.5 | --- | -..|- 
. Sums 10.5 (27.2 |38.6 |1508 | 8.7|-0.7 | 5.1 
Divisors 6 6 6 6 6 6 | 6 A 
| | Means 0.23 | 1675 | 4.55 | 6.43| 257 [1.45 |-0.72 | o.85. 
Greenwith LW i terval, reference 9.94 | 9,94 | 9,94 | 9,94 
Greenwith intervals, |this station 10.27 111.69 114,49 116,37 1.2\cl-0.1@) 0.7]e 
2.07 
EW Ebb Period a le (elie 
Septe24 11.7 1 
w-- 11265 113.5 | 14205 | 1601] 0.8 | 1.8 | 268 | 404 87 | 1200] 004 | 102 
25] 0.2 1,0 | 1.7 | 3.2 0.8 | 1.5 | 3.0 | 4,2 84_| 0.8] 0.2 | 0.9 
125 |1323 |14.2 | 15e1| 168] 0-8 | 1.7 | 206 | 4.3 78_' 1.0} 0.4 | 1.4 
AL NO) 1.6 | 2.6 | 4.0 0.6 | 106 | 3.0 | 405 TM | 0,8] 0,0 | 0.7 
13.2 114.0 |15.0 | 16.1! 18.1} 0.8 | 1.8 | 29 |.4.9 76! 1.0}0,.4 | 1.0 
27) 108 2e7 | 304 | 520! 640] 0,9 | 166 _| 32 | 402 80 | 0.8 |-022 | 0.8 
Sums _| 4,7 (10.0 26.5 | 476 | 5.4] 1.2 | 6.0 
Divisors qe @ Jee a eas 
(eee | Means 0.78; 1067! 2.02| 4.42| 79 |0.90| 0.201 1.00 
Greenwi| 3.77) 3077 d 
Greenwibh intefvals,| this [station 4.55 | 6044 | 6069| 68019 10.75] Ool6c| O83e 
Velocity reduction 
Best known mean range of tide at reference stationeccscscecccecccccces 9040 feet 
Range for observational period at reference stationescscccessccscccee lledd " 
Reduction factor for tidal currentecccecccccecccccccce f = 9e40/11l.35=. 0.83 
Floodecccccccccccce EbDeccccocvccccccccce 
Observed velocitiesecceccscseccses ledS 0.12 0.85 =-0.90 =0.20 =-1.00 
Mean of above, nontidal current 0.01 0.01 0.01 0.01 0.91 0.91 
Observed tidal currenteccecoocee 144 -0.15 0.84 -0.91 0.21 -1.01 
Reduction factoreeccescscccccee 085 0.83 0.835 0.83 0.83 0.83: 
Corrected tidal currentecsecsssce 1e50 <=O5oll 0670 0.76 -O.17 O84 
Nontidal currenteccocceoscexcv0ce 0.01 0.01 0.01 0.91 0.01 0.01 
Corrected velocitieseccsscescece le2zic =-O5el0c O-.71co -0.75c¢ -—Oel6c <=0-83c 
FIGURE 29.—Form 451, Flood, ebb, and slack for double phases 
