BA, Secondary Port
Capt. Yusuf ZORBA
1
BA, Secondary Port
• You learned that how can you calculate tide times and heights for a
specific port.
• Also, you learned that how can you calculate tide times and heights
for secondary ports by US Tide Table’s.
• Our aime for this pratice;
– Using Tide Tables for Secondary Port in British Admiralty
– Finding HW and LW times for Secondary Port
– Finding HW and LW heights for Secondary Port
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BA, Secondary Port
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BA, Secondary Port
• The method of finding the time and heights of HW and LW at any
Secondary Port given in the Admiralty Tide Tables is by means of
simple differences in times and heights from predictions for the
Standart Port indicated, which is the most suitable, Standart Port.
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BA, Secondary Port
• Example 1: Find the times and heights of HW and LW at
Richborough for the PM rising tide on March, 02, 2001.
1. Find the secondary port in the Geographical Index at the back of
ATT (Adm. Tide Table). Note its number.
Richborough : 99
2. Find the Standart Port names and numbers in ATT, Part I
Dover : 89
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BA, Secondary Port
3. Find the HW and LW times and heights at the Standart Port for
the required day. Enter in tables (called NP 204), boxes 1 to 4 and
calculate the range for box 5.
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BA, Secondary Port
3. Find the HW and LW times and heights at the Standart Port for
the required day. Enter in tables (called NP 204), boxes 1 to 4 and
calculate the range for box 5.
Standart Port
Seasonal
Change
HW
LW
1511
1013
Std. Port
HW
LW
6.0
1.5
-
-
RANGE
4.5
Differences
Seasonal
Change
Sec. Port
Secondary Port
Duration
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BA, Secondary Port
4. “Seasonal Change in Mean Level” table from Part II , using its
number and month find the Standart Port’s Seasonal Change.
Seasonal Changes In Mean Level for number 89 and 99 is same;
“ -0,1 ” We change its signed, because of Standart Port heights include
the Seasonal Standart Port
HW
LW
HW
LW
RANGE
1
2
3
4
5
Change.
1511
Seasonal
Change
Differences
Seasonal
Change
Secondary Port
Duration
1013
Std. Port
7
8
Sec. Port
12
13
6.0
6
1.5
4.5
6
0.1
0.1
9
10
11
11
14
15
16
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BA, Secondary Port
5. Note the time and height differences for the secondary port and the
related reference times and reference heights at the Standart Port.
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BA, Secondary Port
6. Interpolate between Secondary Port time differences and height
differences.
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BA, Secondary Port
6. Interpolate between Secondary Port time differences and height
differences.
Interpolation methods:
1. Using graph paper
2. Using mathematical methods
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6.1. Using graph paper for interpolation;
+70
+60
+50
+40
+30
+30
+20+15 +10
1300
1800
1013
1511
0700
1200
12
6.1. Using graph paper for interpolation;
+70
+60
+50
+40
+30
+30
+20+15 +10
1300
1800
1013
1511
6.0 m
1200
0700
4.0 m
2.0 m
0.0 m
-4
-3
-2
-1
0.0
+1
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6.1. Using graph paper for interpolation;
Standart Port
Seasonal
Change
Differences
Seasonal
Change
Secondary Port
Duration
HW
LW
1
1511
2
1013
Std. Port
7
8
Sec. Port
12
13
HW
LW
3
6.0
4 1.5
6
0.1
6
RANGE
5
4.5
0.1
9
10
11
11
14
15
16
14
6.1. Using graph paper for interpolation;
+70
For 6.1
+60
+50
+40
+30
+30
+20+15 +10
1300
1800
1013
1511
6.0 m
1200
0700
4.0 m
2.0 m
For 1.6
0.0 m
-4
-3
-3.1
-2
-1
-1.3
0.0
+1
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BA, Secondary Port
And we complete in boxes 7, and 8, 9, 10.
Standart Port
Seasonal
Change
Differences
Seasonal
Change
Secondary Port
Duration
HW
LW
1
1511
2
1013
Std. Port
7
00:15
8
00:30
Sec. Port
12
13
HW
LW
3
6.0
4 1.5
6
0.1
6
9
-3.1
RANGE
5
4.5
0.1
10
-1.3
11
11
14
15
16
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6.2. Using mathematical methods
We will make a interpolation for secondary port differences.
For times;
12:00 to 18:00
if +00:15 to +00:15
And our HW time is 15:11 we can say that is same (+00:15)
07:00 to 13:00
if +00:30 to +00:30
And our LW time is 10:13 we can say that is same (+00:30)
And we enter this results into boxes #7 and #8.
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6.2. Using mathematical methods
We will make a interpolation for secondary port differences.
For heights;
For HW
5.3 to 6.8
if – 2.6 to – 3.4
and our height is
6.1
= (0.8 x 0.8)/1.5 = 0.46
so, our differences for HW
For LW
And our height is
0.8 to 2.1
1.6
And our differences for HW
(-2.6)+(-0.46)= ~ -3.1
if – 0.7 to – 1.7
= (0.8 x 1.0)/1.3 = 0.62
(-0.7)+(-0.62)= ~ -1.3
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And we complete in boxes 7, and 8, 9, 10.
7. Using Secondary Port number to locate the right line, find and enter
the Secondary Port’s Seasonal Change for the month in boxes 11.
Richborough : 99
8. Apply
Standart Port
HW
LW
HW
LW
RANGE
1
3 6.0
4 1.5
5 4.5
differences to
1511 21013
6
6
Standart Port
Seasonal
0.1
0.1
Std. Port
Change
times and heights
7
8
9
10
Differences
00:15 00:30 - 3.1
- 1.3
to find times at
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11
Seasonal
Sec. Port
- 0.1
- 0.1
Change
the Secondary
12
13
14
15
Secondary
Port
15:26 10:43
2.9
0.2
Port
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Duration
----(boxes 12-15)
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BA, Secondary Port
• Example 1: Find the times and heights of HW and LW at
Richborough for the PM rising tide on March, 02, 2001.
• Richborough March, 02, 2001
Time
10:43
15:26
Height
0.2
2.9
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