Speed of Current At Any Time
NOTE: Use table A for all places except those listed below for table B. Use Table B for Cape Code
Canal, Hell Gate, Chesapeake and Delaware Canal, and all stations in table 2 which are referred to
them.
TABLE A
Interval between slack and maximum current
h:m 1:20 1:40 2:00 2:20 2:40 3:00 3:20 3:40 4:00 4:20 4:40 5:00 5:20 5:40
0:20 0.5 0.4 0.4 0.3 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.2 0.2
0:40 0.8 0.7 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3
1:00 0.9 0.8 0.8 0.7 0.7 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.4
1:20 1.0 1.0 0.9 0.8 0.8 0.7 0.7 0.6 0.6 0.6 0.5 0.5 0.5 0.5
1:40 - 1.0 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.7 0.6 0.6 0.6 0.6
2:00 --1.0 1.0 0.9 0.9 0.9 0.8 0.8 0.7 0.7 0.7 0.7 0.6
2:20 --- 1.0 1.0 1.0 0.9 0.9 0.8 0.8 0.8 0.7 0.7 0.7
2:40 ----1.0 1.0 1.0 0.9 0.9 0.9 0.8 0.8 0.8 0.7
3:00 ----- 1.0 1.0 1.0 0.9 0.9 0.9 0.9 0.8 0.8
3:20 --- ---1.0 1.0 1.0 1.0 0.9 0.9 0.9 0.9
3:40 --- ---- 1.0 1.0 1.0 1.0 0.9 0.9 0.9
4:00 --- -----1.0 1.0 1.0 1.0 0.9 0.9
4:20 --- ------ 1.0 1.0 1.0 1.0 0.9
4:40 --- -------1.0 1.0 1.0 1.0
5:00 --- ------- - 1.0 1.0 1.0
Interval between slack and desired time
5:20 --- ------- --1.0 1.0
5:40 --- ------- --- 1.0
s
TABLE B
Interval between slack and maximum current
r
e
nt
h:m 1:20 1:40 2:00 2:20 2:40 3:00 3:20 3:40 4:00 4:20 4:40 5:00 5:20 5:40
u
r
0:20 0.4 0.3 0.3 0.2 0.2 0.2 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1
C
0:40 0.7 0.6 0.5 0.4 0.4 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.2
1:00 0.9 0.8 0.7 0.6 0.6 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.3
1:20 1.0 1.0 0.9 0.8 0.7 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.4
1:40 - 1.0 1.0 0.9 0.8 0.8 0.7 0.7 0.6 0.6 0.5 0.5 0.5 0.4
2:00 --1.0 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.6 0.6 0.6 0.5
2:20 --- 1.0 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.7 0.6 0.6
2:40 -----1.0 1.0 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.7 u
r
r
e
n
t
3:00 ----- 1.0 1.0 1.0 0.9 0.9 0.8 0.8 0.8 0.7
3:20 --- ---1.0 1.0 1.0 0.9 0.9 0.9 0.8 0.8
f C
3:40 --- ---- 1.0 1.0 1.0 0.9 0.9 0.9 0.9
4:00 --- -----1.0 1.0 1.0 1.0 0.9 0.9
4:20 --- ------ 1.0 1.0 1.0 1.0 0.9
peed o
4:40 --- -------1.0 1.0 1.0 1.0
Interval between slack and desired time
5:00 --- ------- - 1.0 1.0 1.0 s/S
5:20 --- ------- --1.0 1.0
c
e
5:40 --- ------- --- 1.0
o
ti
INSTRUCTIONS
1. From predictions find the time of slack water and the time and velocity of maximum current
o
n/N
(flood or ebb), one of which is immediately before and the other after the time for which the veloc-
ity is desired.
2. Find the interval of time between the above slack and maximum current, and enter the top of
u
c
ti
table A or B with the interval which most nearly agrees with this value.
od
3. Find the interval of time between the above slack and the time desired, and enter the side of
table A or B with the interval which most nearly agrees with this value.
I
n
tr
4. Find, in the table, the factor corresponding to the above two intervals, and multiply the maxi-
mum velocity by this factor. The result will be the approximate velocity at the time desired.
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