BA, Secondary Port

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BA, Secondary Port

• Capt. Yusuf ZORBA

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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
  Tables.
• 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.
1511
1013
6.0
1.5
4.5
- -
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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 Ports 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 Change.
1511 1013 6.0 1.5 4.5
0.1 0.1
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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. Interpolatio
n methods 1. Using graph paper 2. Using
mathematical methods
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6.1. Using graph paper for interpolation
30
15
20
30
40
50
60
70
10
1800
1300
1511
1013
1200
0700
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6.1. Using graph paper for interpolation
30
15
20
30
40
50
60
70
10
1800
1300
1511
1013
6.0 m
1200
0700
4.0 m
2.0 m
0.0 m
- 3
- 2
- 1
0.0
1
- 4
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6.1. Using graph paper for interpolation
1511 1013 6.0 1.5 4.5
0.1 0.1
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6.1. Using graph paper for interpolation
30
15
20
30
40
50
60
70
10
1800
1300
1511
1013
For 6.1
6.0 m
1200
0700
4.0 m
2.0 m
For 1.6
0.0 m
- 3
- 2
- 1
0.0
1
- 4
-3.1
-1.3
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BA, Secondary Port
And we complete in boxes 7, and 8, 9, 10.
1511 1013 6.0 1.5 4.5
0.1 0.1
0015 0030 -3.1 -1.3
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6.2. Using mathematical methods
We will make a interpolation for secondary port
differences. For times 1200 to 1800 if 0015
to 0015 And our HW time is 1511 we can say
that is same (0015) 0700 to 1300 if 0030
to 0030 And our LW time is 1013 we can say
that is same (0030) 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
(-2.6)(-0.46) -3.1 For LW 0.8 to 2.1
if 0.7 to 1.7 And our height is 1.6 ?
(0.8 x 1.0)/1.3 0.62 And our differences for HW
(-0.7)(-0.62) -1.3
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BA, Secondary Port
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 Ports
Seasonal Change for the month in boxes
11. Richborough 99 8. Apply differences to
Standart Port times and heights to find times
at the Secondary Port (boxes 12-15)
1511 1013 6.0 1.5 4.5
0.1 0.1
0015 0030 - 3.1 - 1.3
- 0.1 - 0.1
1526 1043 2.9 0.2
- - - - -
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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 Height
• 1043 0.2
• 1526 2.9