Tides & astro consolidation lrg

Grunt Productions 2007

Tides & Astro Tides & Astro ConsolidationConsolidation

A series of miscellaneous A series of miscellaneous examplesexamples

A brief by Lance GrindleyA brief by Lance Grindley


Example 1Example 1

Your ship will be entering PLYMOUTH Your ship will be entering PLYMOUTH when the predicted height of tide is when the predicted height of tide is 4.5 metres. If the draught of your 4.5 metres. If the draught of your vessel is 7.2 metres, at what depth vessel is 7.2 metres, at what depth should the limiting danger line (LDL) should the limiting danger line (LDL) be drawn?be drawn?


Example 1 (Answer)Example 1 (Answer)

7.2m

2.0m

Chart Datum 4.5m

7.2m + 2.0m - 4.5m = 4.7m

Charted Depth


Example 2Example 2

Lying alongside in GREENOCK, if Lying alongside in GREENOCK, if your maindeck is at a height 3.6 your maindeck is at a height 3.6 metres above the waterline, what metres above the waterline, what height of tide would be required to height of tide would be required to make the deck level with the jetty, make the deck level with the jetty, having a charted height of 2.5 metres?having a charted height of 2.5 metres?



Jetty Deck

3.6m

Chart DatumChart Datum

Height Height of Tideof Tide

MHWSMHWS2.5m

3.4m3.4m

2.5m + 3.4m - 3.6m = 2.3m


Example 3Example 3

What is the predicted height of tide in What is the predicted height of tide in PORTSMOUTH at 1200A on Wednesday PORTSMOUTH at 1200A on Wednesday 5 August, 1998?5 August, 1998?

HWHW LWLW HWHW LWLW RangeRange09090909 14361436 4.1m4.1m 1.6m1.6m 2.5m2.5mHW 1009AHW 1009A 30%sp30%sp



HW +1 +2 +3 +4 +5-1-2-3-4-5-6

0 2 43 51

0 21 3

MEAN RANGESSprings 3.9mNeaps 1.9m

PORTSMOUTH

1009A

HW 4.1m

1200ALW 1.6m

3.7m


Example 4Example 4

What time will the predicted height of What time will the predicted height of tide rise to 7.0 metres during the tide rise to 7.0 metres during the morning on Tuesday 23 June, 1998, in morning on Tuesday 23 June, 1998, in BRISTOL (AVONMOUTH)?BRISTOL (AVONMOUTH)?

HWHW LWLW HWHW LWLW RangeRange06100610 12581258 12.9m12.9m 1.0m1.0m 11.9m11.9mHW 0710AHW 0710A 95%sp95%sp



+1 +2 +3 +4 +5 +6HW-1-2-3-4-5

0 4 862

0 42 6


AVONMOUTH10 12 14

0710A0410A


Example 5Example 5

What is the predicted height of tide in What is the predicted height of tide in SAINT JOHN, NB at 0900(+3) on SAINT JOHN, NB at 0900(+3) on Tuesday 22 September, 1998?Tuesday 22 September, 1998?

HWHW LWLW HWHW LWLW RangeRange12451245 06400640 7.6m7.6m 1.0m1.0m 6.6m6.6m6hr 05min 6hr 05min



+1 +2 +3 +4 +5 +6HW-1-2-3-4-5

00

42

84

63

21

00

24

12

36

+7-6-7

105

126

147

1345(+3)1.8m


Example 6Example 6

What time will the predicted height of What time will the predicted height of tide fall to 2.0 metres during the tide fall to 2.0 metres during the afternoon of Thursday 29 January, afternoon of Thursday 29 January, 1998, in KARACHI? Give your answer 1998, in KARACHI? Give your answer in legal time.in legal time.

HWHW LWLW HWHW LWLW RangeRange11141114 17271727 2.6m2.6m -0.2m-0.2m 2.8m2.8m6hr 13min 6hr 13min



+1 +2 +3 +4 +5 +6HW-1-2-3-4-5

00

42

84

63

21

00

24

12

36

+7-6-7

105

126

147

1114(-5)1315(-5)


Example 7Example 7

What is the predicted height of tide in What is the predicted height of tide in CARDIFF(514) at 1600A on Thursday CARDIFF(514) at 1600A on Thursday 18 June, 1998?18 June, 1998?


Example 7 - Tidal Example 7 - Tidal Prediction FormPrediction Form

STANDARD PORT……………………TIME/HEIGHT REQUIRED…………

SECONDARY PORT…………………..DATE…..……….TIME ZONE……...

STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Cardiff

Avonmouth 1600

18 Jun A

1311 11.0m1931 2.9m 8.1m

34%Sp-0015 -0033 -0.7m +0.1m

1256 1858 10.3m 3.0m

HW 1356A



+1 +2 +3 +4 +5 +6HW-1-2-3-4-5

0 4 862

0 42 6


AVONMOUTH10 12 14

1356A

8.0m


Example 8Example 8

What time should you sail from What time should you sail from PORTSMOUTH to arrive in HALIFAX, PORTSMOUTH to arrive in HALIFAX, Nova Scotia, at 0900(+3) on Friday 26 Nova Scotia, at 0900(+3) on Friday 26 June, if the overall distance is June, if the overall distance is 2,562nm using an overall passage 2,562nm using an overall passage speed of 14 knots. Give your ETD in speed of 14 knots. Give your ETD in local time and allow time in hand (TIH) local time and allow time in hand (TIH) of one hour per day or part of a day.of one hour per day or part of a day.



Distance 2562 at 14 knots = 183h = 7 days 15 hoursTime in hand 8 hours

Total time on passage 7 days 23 hours

ETA Halifax 260900(+3)261200Z

Passage Time 072300ETD Portsmouth 181300Z JUN DST Zone (-1) +0100

ETD Portsmouth 181400(-1) JUN


Example 9Example 9

Ship’s time is zone (+3). How should Ship’s time is zone (+3). How should you adjust your clocks to legal time you adjust your clocks to legal time before entering ST JOHNS, before entering ST JOHNS, Newfoundland, when DST is not being Newfoundland, when DST is not being kept?kept?

Clocks initially 3 hours behind UTClocks initially 3 hours behind UT Newfoundland (+3½) or 3½ behind UTNewfoundland (+3½) or 3½ behind UT Therefore Therefore retardretard clocks by 30 minutes clocks by 30 minutes


Rising & SettingRising & Setting

Example 10.Example 10. What time will sunset What time will sunset occur on 5 February, 1997, in position occur on 5 February, 1997, in position 47º 00’N, 041º 15’W? Give your 47º 00’N, 041º 15’W? Give your answer in Zone Time (+3).answer in Zone Time (+3).

Example 11.Example 11. What time is evening What time is evening nautical twilight (ENT) on 6 February, nautical twilight (ENT) on 6 February, 1997, in position 42º 00’S, 031º 30’E? 1997, in position 42º 00’S, 031º 30’E? Give your answer in Zone Time (-2).Give your answer in Zone Time (-2).


Example 10Example 10Port……..……… Date…………..DR Lat…..….. DR Long…….... Zone....

Higher Lat.

Lower Lat.

Latitude Increment

Daily Change/Long Corrn

Local Mean Time (LMT)

Arc to Time (Longitude)

Universal Time (UT/GMT)

Zone ( )(Change sign)

Zone Time

Diff.

Daily Change

Time Diff.

5 Feb 8747o00N 41o15W +3

50oN

45oN

1659

1712-13

-0005 1716 +4/3

+0001

1708

+0245

1953

-0300

1653


Example 11Example 11Port……..……… Date…………..DR Lat…..….. DR Long…….... Zone....

Higher Lat.

Lower Lat.

Latitude Increment

Daily Change/Long Corrn

Local Mean Time (LMT)

Arc to Time (Longitude)

Universal Time (UT/GMT)

Zone ( )(Change sign)

Zone Time

Diff.

Daily Change

Time Diff.

6 Feb 8742o00S 31o30E -2

45oS

40oS

2034

2016+18

+0007 2020 +4/3

+0001

2024

-0206

1818

+0200

2018


Example 12Example 12

You carry out a gyro check at about You carry out a gyro check at about 1710(+2) just before sunset, when the 1710(+2) just before sunset, when the sun’s lower limb appears to lie a semi-sun’s lower limb appears to lie a semi-diameter above the visible horizon diameter above the visible horizon (True Sunset) on 6 February, 1997. (True Sunset) on 6 February, 1997. Your DR position is 47º 00’N, 035º Your DR position is 47º 00’N, 035º 00’W and the gyro bearing was 248º. 00’W and the gyro bearing was 248º. What was the gyro error?What was the gyro error?



Time 1710(+2) is 1910Z

Declination at 1900Z S15º 25.3’ or 15.4º

Latitude 47º

Amplitude 22.9º or W23ºS

True bearing 270º - 23º = 247º

Gyro bearing 248º Error is 1º HIGH


Questions??Questions????

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Tides & astro consolidation lrg