Tides and tidal streams 1 lrg

Grunt Productions 2006

Tides and Tidal Tides and Tidal StreamsStreams

Using Admiralty Tidal Using Admiralty Tidal PublicationsPublications

A brief by Lance GrindleyA brief by Lance Grindley


“Everyone can just put down their loot and plunder - Sven here has something to say to us all!”


NWC AssessmentNWC Assessment

Award of MCA certification is subject to Award of MCA certification is subject to successful completion of written successful completion of written examination in “Tides and Times”.examination in “Tides and Times”.

Criteria for evaluating competence - Criteria for evaluating competence - “Calculations and measurement of “Calculations and measurement of navigational information are accurate.”navigational information are accurate.”

Use Tide Tables to work out height of Use Tide Tables to work out height of tide at any place or time a chosen tide at any place or time a chosen height is achieved.height is achieved.


Range of LessonRange of Lesson

Calculating heights and depths from Calculating heights and depths from levels and datums.levels and datums.

Calculating predicted heights for any Calculating predicted heights for any Standard Port (European and Non-Standard Port (European and Non-European)European)

Calculating predicted heights for Calculating predicted heights for European and Non-European Secondary European and Non-European Secondary Ports (including Solent)Ports (including Solent)

Calculating tidal streams using tidal Calculating tidal streams using tidal diamonds and Tidal Stream Atlasesdiamonds and Tidal Stream Atlases


IntroductionIntroduction

Basic principles of tides.Basic principles of tides.

The tide raising forces of The tide raising forces of the Moon and the Sun.the Moon and the Sun.


The Earth-Moon SystemThe Earth-Moon System

Moon

Earth

Gravitational Attraction

Barycentre


Daily Tidal PeriodDaily Tidal Period

Moon

Earth

Start - HW

+ 6 hours

+ 12 hours

+ 18 hours

+ 24 hours

+ 25 hours


Tidal PeriodTidal Period

The Lunar Day lasts just under 25 The Lunar Day lasts just under 25 hours.hours.

In each period of 24 hours there will be In each period of 24 hours there will be two HW and two LW.two HW and two LW.

Each HW and LW will occur Each HW and LW will occur approximately 6 hours 10 minutes after approximately 6 hours 10 minutes after each other.each other.

The predicted times of HW and LW get The predicted times of HW and LW get progressively later each day by about progressively later each day by about one hour.one hour.


The Sun-Moon SystemThe Sun-Moon SystemNew MoonNew Moon

Moon

Earth

Lunar Tide

Solar Tide


The Sun-Moon SystemThe Sun-Moon SystemFull MoonFull Moon

Moon

Earth


The Sun-Moon SystemThe Sun-Moon SystemFirst/Last QuarterFirst/Last Quarter

Moon

Earth

Moon


Spring and Neap TidesSpring and Neap Tides

In each Lunar Month there will be a New In each Lunar Month there will be a New Moon and a Full Moon.Moon and a Full Moon.

At this period the range will be a At this period the range will be a maximum range which is called a Spring maximum range which is called a Spring Tide.Tide.

The Moon will also pass two period of The Moon will also pass two period of quadrature and the range will be a quadrature and the range will be a minimum which is called a Neap Tide.minimum which is called a Neap Tide.

Tides of this pattern are called Semi-Tides of this pattern are called Semi-Diurnal Tides and occur throughout the Diurnal Tides and occur throughout the Atlantic region. Atlantic region.


Tidal PredictionTidal Prediction

Admiralty Tide Tables (4 volumes)Admiralty Tide Tables (4 volumes) Volume 1 UK and Channel CoastVolume 1 UK and Channel Coast Volume 2 European and Atlantic Volume 2 European and Atlantic WatersWaters

Volume 3 Indian OceanVolume 3 Indian Ocean Volume 4 Pacific Ocean.Volume 4 Pacific Ocean.


Limits of Tide TablesLimits of Tide Tables


Heights and DatumsHeights and Datums

All depths and drying heights are All depths and drying heights are measured from the Chart Datum.measured from the Chart Datum.

Chart Datum is usually set at LATChart Datum is usually set at LAT Tidal levels LAT, MLWS, MLWN, MSL, Tidal levels LAT, MLWS, MLWN, MSL,

MHWN, MHWS and HAT are given as MHWN, MHWS and HAT are given as heights above Chart Datum.heights above Chart Datum.

All heights are measured from MHWS.All heights are measured from MHWS.


Tidal Tidal Levels Levels

and and DatumsDatums

DATUM FOR HEIGHTS

DATUM FOR DEPTHS

LAND LEVELLING DATUM


Tidal DatumsTidal Datums

MHWS

Chart Datum

MLWS

MHWN

MLWN

HAT

LAT

MSL


Mean Spring RangeMean Spring Range

MHWS

Chart Datum

MLWSMean Spring Range


Charted HeightCharted Height

MHWS

Chart Datum

Charted Height

Height above

waterline

Height of TideHeight of TideHeight of MHWS Height of MHWS above Chart above Chart DatumDatum


Underkeel ClearanceUnderkeel Clearance

DraughtDraughtHeight Height of Tideof Tide

Charted DepthCharted DepthTide + Depth - DraughtTide + Depth - Draught

Chart DatumChart Datum


Minimum Clearance 2mMinimum Clearance 2m

DraughtDraughtMinimum Minimum Height of TideHeight of Tide

Charted DepthCharted Depth 2m minimum2m minimumChart DatumChart Datum


Masthead ClearanceMasthead Clearance

Maximum Maximum Height of TideHeight of Tide

MHWS

Charted HeightCharted HeightMasthead ClearanceMasthead Clearance

Chart DatumChart Datum

Masthead Masthead HeightHeight


ExampleExample

Port of MILFORD HAVENPort of MILFORD HAVEN Power cable with charted height 24mPower cable with charted height 24m Minimum charted depth 4mMinimum charted depth 4m Vessel details: Vessel details: - masthead height - masthead height

22m22m - draught 6m.- draught 6m. Clearances:Clearances: - masthead 3m- masthead 3m - underkeel 2m- underkeel 2m


DiagramDiagram

Cable

Seabed

22m

6m Chart Datum4mHoT

MHWS7m

24m

3m

2m

4m6m


Max/min height of tideMax/min height of tide

Minimum HoT Minimum HoT = 6m+2m-4m = = 6m+2m-4m = 4 4 metresmetres

Maximum HoT Maximum HoT = 24m+7m-= 24m+7m-(22m+3m)(22m+3m)

31m - 25m = 31m - 25m = 6 6 metresmetres

Height of tide must lie between 4 and Height of tide must lie between 4 and 6 metres 6 metres


The Tidal CurveThe Tidal Curve

Time

Height of Tide

Chart Datum

HW

Predicted Height

LW

Range of Tide

Duration

Rise of Tide

LW

Interval

Height of Tide


Express Range as PercentageExpress Range as Percentage Difference between the Mean Neap Range Difference between the Mean Neap Range

and the Mean Spring Range is 100%.and the Mean Spring Range is 100%. Any range can be expressed as a Any range can be expressed as a

percentage increase from the MNR.percentage increase from the MNR. Example (Portsmouth) MSR 3.9m MNR Example (Portsmouth) MSR 3.9m MNR

1.9m1.9m Difference of 2.0m represents 100% Difference of 2.0m represents 100%

SpringsSprings Range of 3.0m is 3.0-1.9/2.0 =Range of 3.0m is 3.0-1.9/2.0 = 1.1/2.0 = 1.1/2.0 =

55%55%


Hourly PredictionsHourly Predictions

Found in ATT Volume 1 Part 1aFound in ATT Volume 1 Part 1a Eight ports are included:Eight ports are included: Plymouth; Poole Harbour; Plymouth; Poole Harbour;

Southampton; Portsmouth; Southampton; Portsmouth; Rosyth; Liverpool; Avonmouth; Rosyth; Liverpool; Avonmouth; St. HelierSt. Helier


European PortsEuropean Ports


PublicationsPublications

Admiralty Tide Tables Volume 1 Admiralty Tide Tables Volume 1 (United Kingdom and Ireland) (United Kingdom and Ireland) (Including European Channel Ports).(Including European Channel Ports).

Admiralty Tides Tables Volume 2 Admiralty Tides Tables Volume 2 (Europe excluding United Kingdom (Europe excluding United Kingdom and Ireland) Mediterranean Sea and and Ireland) Mediterranean Sea and Atlantic Ocean.Atlantic Ocean.

Admiralty List of Radio Signals Admiralty List of Radio Signals Volume 2 (Radio Time Signals).Volume 2 (Radio Time Signals).


Standard PortsStandard Ports

List of ports inside front cover of ATT.List of ports inside front cover of ATT. Predictions are given in the Predictions are given in the OfficialOfficial

Standard Time Standard Time for the country. (This for the country. (This happens to be Universal Time in the United happens to be Universal Time in the United Kingdom.)Kingdom.)

If necessary times must be adjusted for If necessary times must be adjusted for Daylight Saving Time (DST) usually one Daylight Saving Time (DST) usually one hour ahead of standard time.hour ahead of standard time.

First page of standard port predictions will First page of standard port predictions will be the tidal curve unique to that port.be the tidal curve unique to that port.


Tidal Curve - DoverTidal Curve - Dover

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

0 4 862

0 42 6

MEAN RANGESSprings 6.0mNeaps 3.2m

DOVER


Tidal Curve - SouthamptonTidal Curve - Southampton

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

0 2 431

0 21 3


SOUTHAMPTON


Tidal Prediction FormTidal Prediction 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 +


Portsmouth PredictionsPortsmouth PredictionsENGLAND - PORTSMOUTH

Lat 50 48’N Long 1 07’WTIME ZONE UT (GMT) TIMES AND HEIGHTS OF HIGH AND LOW WATERS YEAR 1998

JUNE JULYTime m Time m Time m Time m0338 4.1 0301 4.3 0458 0.8 0435 0.91 0911 1.4 16 0838 1.1 1 1144 4.8 16 1119 4.61819 4.1 1543 4.4 1723 0.6 1657 0.7M2140 1.7

F2109 1.3

M TU 2347 4.7

0427 3.9 0356 4.2 0015 4.8 0515 0.82 1008 1.6 17 0937 1.3 2 0539 0.8 17 1200 4.61715 4.0 1641 4.3 1227 4.7 1738 0.6TU2244 1.8

SA2213 1.4

TU1803 0.6

W

0527 3.7 0459 4.1 0056 4.7 0027 4.73 1114 1.8 18 1044 1.3 3 0618 0.8 18 0555 0.61819 3.9 1747 4.3 1306 4.7 1242 4.7W2354 1.9

SU2324 1.5

W1840 0.7

TH1817 0.5

0638 3.7 0609 4.1 0133 4.7 0108 4.84 1221 1.8 19 1157 1.3 4 0654 0.9 19 0635 0.61924 4.0 1857 4.3 1343 4.5 1324 4.7TH M TH

1914 0.8F

1857 0.5

0058 1.8 0037 1.4 0208 4.6 0150 4.85 0746 3.8 20 0722 4.2 5 0728 1.1 20 0716 0.61320 1.7 1307 1.2 1419 4.4 1407 4.7F2019 4.1

SA2003 4.5

F1946 1.0

SA1939 0.6

0151 1.6 0144 1.2 0243 4.5 0233 4.76 0841 3.9 21 0830 4.3 6 0802 1.3 21 0800 0.81408 1.5 1409 1.1 1455 4.2 1452 4.5TU2105 4.2

SU2103 4.6

SA2019 1.2

SU2023 0.8





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Portsmouth

5 June

1100

A

0746 3.8m1320 1.7m 2.1m

0846A

10% Sp


Tidal Curve - PortsmouthTidal Curve - Portsmouth

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

0 2 43 51

0 21 3


PORTSMOUTH

0846A

HW 3.8m

1100ALW 1.7m

3.3m


Secondary PortsSecondary Ports

Times and heights are obtained by Times and heights are obtained by applying time and height differences to applying time and height differences to Standard Port predictions.Standard Port predictions.

Obtain Port Number from Geographical Obtain Port Number from Geographical Index at back of ATT.Index at back of ATT.

Use Part II (page 300-323) to obtain:Use Part II (page 300-323) to obtain: Standard PortStandard Port Secondary Port time ZoneSecondary Port time Zone Secondary Port differencesSecondary Port differences..


ExampleExample

Find out what time the height of tide Find out what time the height of tide will first rise to 5.0 metres at will first rise to 5.0 metres at WATCHET (531) on 26th July, 1989.WATCHET (531) on 26th July, 1989.

Page 2A-102 for Secondary Port Page 2A-102 for Secondary Port Differences.Differences.


Secondary Port DifferencesSecondary Port Differences

WALES; ENGLAND, WEST COAST

No PLACE TIME DIFFERENCES HEIGHT DIFF (METRES)Lat Long High Water Low Water MHWS MHWN MLWN MLWS N W Zone UT (GMT)

0200 0800 0300 0800523 PORT OF BRISTOL and and and and 13.2 9.8 3.8 1.0(AVONMOUTH) …(see page 158) 1400 2000 1500 2000

531 Watchet 51 11 3 20 -0035 -0050 -0145 -0040 -1.9 -1.5 +0.1 +0.1





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Avonmouth 5.0m

Watchet 26 Jul A

0858 12.8m0328 1.1m 11.7m

92% Sp


High Water DifferencesHigh Water Differences




531 Watchet 51 11 3 20 -0035 -0050 -0145 -0040 -1.9 -1.5 +0.1 +0.1

1400 - 0858 - 0800

-0035 -0050

-48 min


Interpolation of HW TimesInterpolation of HW Times

0800 0900 1000 1100 1200 1300 1400

Times of HW at Bristol

Watchet Differences

-50 min -35 min-48m --45m -43m -40m -38m


Low Water DifferencesLow Water Differences




531 Watchet 51 11 3 20 -0035 -0050 -0145 -0040 -1.9 -1.5 +0.1 +0.1

0300 - 0328 - 0800

-0145 -0040

-0138


Interpolation of LW TimesInterpolation of LW Times

0300 0400 0500 0600 0700 0800

Times of LW at Bristol

Watchet Differences

-105m -92m --79m -66m -53m -40m


High Water CorrectionHigh Water Correction




531 Watchet 51 11 3 20 -0035 -0050 -0145 -0040 -1.9 -1.5 +0.1 +0.1

12.8m

13.2m 9.8m

-1.9m -1.5m

-1.9m -1.8m -1.7m -1.6m -1.5m

13.2m 12.4m 11.5m 10.7m 9.8m


Low Water CorrectionLow Water Correction




531 Watchet 51 11 3 20 -0035 -0050 -0145 -0040 -1.9 -1.5 +0.1 +0.1

1.1m





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Avonmouth 5.0m

Watchet 26 Jul A

0858 12.8m0328 1.1m 11.7m

-0048 -0138 -1.9m +0.1m

0810Z 0150Z 10.9m 1.2m

0910A

92% Sp


Tidal Curve - AvonmouthTidal Curve - Avonmouth

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

0 4 862

0 42 6


AVONMOUTH10 12 14

0910A0550A


Solent PortsSolent Ports

Times and heights are obtained by Times and heights are obtained by applying time and height applying time and height differences to PORTSMOUTH.differences to PORTSMOUTH.

All ports 37 to 70 are listed on All ports 37 to 70 are listed on pages 323/324 (2A-90).pages 323/324 (2A-90).

Curves listed on pages xxii to xxiv Curves listed on pages xxii to xxiv using separate curves for each using separate curves for each group of ports.group of ports.

Curves are based on Low Water.Curves are based on Low Water. Obtain differences in the normal Obtain differences in the normal

way.way.


Stansore Point CurveStansore Point Curve

LW-1-3 -2-5 -4-7 -6 +1 +4+3+2 +6+5 +70 1 2 3 4 5

50 1 2 3 4

Bucklers HardStansore PointLeeFolly InnNewport

Range at PortsmouthSp 3.9mNp 1.9m


Lymington/Yarmouth CurveLymington/Yarmouth Curve

LW-1-3 -2-5 -4-7 -6 +1 +4+3+2 +6+5 +70 1 2 3 4 5

50 1 2 3 4

LymingtonYarmouth

Range at Portsmouth

Sp 3.9m 2.6mNp 1.9m


ExampleExample

What time will the height of tide first What time will the height of tide first rise to 3.0 metres at STANSORE rise to 3.0 metres at STANSORE POINT on 2 June?POINT on 2 June?

Portsmouth predictions LW 2140 Portsmouth predictions LW 2140 1.7m, HW 0427 3.9m1.7m, HW 0427 3.9m





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Portsmouth 3.0m

Stansore Pt 2 Jun A

0427Z 2140Z 3.9m 1.7m 2.2m

15%Sp


Solent Port DifferencesSolent Port Differences

ENGLAND, SOUTH COAST


0000 0600 0500 110065 PORTSMOUTH and and and and 4.7 3.8 1.9 0.8

1200 1800 1700 2300

37 Bournemouth 50 43 1 52 -0240 +0055 -0050 -0030 -2.7 -2.2 -0.8 -0.338 Christchurch 50 43 1 45 -0230 +0030 -0035 -0035 -2.9 -2.4 -1.2 -0.2

39 Hurst Point 50 42 1 33 -0115 -0005 -0030 -0025 -2.0 -1.5 -0.5 -0.140 Lymington 50 46 1 32 -0110 +0005 -0020 -0020 -1.7 -1.2 -0.5 -0.143 Stansore Point 50 47 1 21 -0050 -0010 -0005 -0010 -0.9 -0.6 -0.2 -0.0

Isle of Wight45 Yarmouth 50 42 1 30 -0105 +0005 -0025 -0030 -1.6 -1.3 -0.4 0.046 Totland Bay 50 41 1 33 -0130 -0045 -0040 -0040 -2.0 -1.5 -0.5 0.148 Freshwater 50 40 1 31 -0210 +0025 -0040 -0020 -2.1 -1.5 -0.4 0.0

51 Ventnor 50 36 1 12 -0025 -0030 -0025 -0030 -0.8 -0.6 -0.2 +0.253 Sandown 50 39 1 09 0000 +0005 =0010 +0025 -0.6 -0.5 -0.2 0.053a Foreland (Slip) 50 41 1 04 -0005 0000 +0005 +0010 -0.1 -0.1 0.0 +0.154 Bembridge Hbr 50 42 1 06 -0010 +0005 +0020 0000 -1.6 -1.5 -1.4 -0.658 Ryde 50 44 1 07 -0010 +0010 -0005 -0010 -0.2 -0.1 0.0 +0.1


Interpolation of HW TimesInterpolation of HW Times

0000 0100 0200 0300 0400 0500 0600

Times of HW at Portsmouth

Stansore Point Differences

-50 min -10 min-43m --37m -30m -23m -17m

0427

-20m





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Portsmouth 3.0m

Stansore Pt 2 Jun A

0427Z 2140Z 3.9m 1.7m 2.2m

15%Sp-0020 -0009 -0.6m -0.2m

0407Z 2131Z 3.3m 1.5m

2231A


Stansore Point CurveStansore Point Curve

LW-1-3 -2-5 -4-7 -6 +1 +4+3+2 +6+5 +70 1 2 3 4 5

50 1 2 3 4

Bucklers HardStansore PointLeeFolly InnNewport

Range at PortsmouthSp 3.9mNp 1.9m

2231A

0415A


Non-European PortsNon-European Ports


PublicationsPublications

Admiralty Tides Tables Volume 2 Admiralty Tides Tables Volume 2 (Europe excluding United Kingdom and (Europe excluding United Kingdom and Ireland) Mediterranean Sea and Atlantic Ireland) Mediterranean Sea and Atlantic Ocean.Ocean.

Admiralty Tide Tables Volume 3 (Indian Admiralty Tide Tables Volume 3 (Indian Ocean and South China Sea) & Volume Ocean and South China Sea) & Volume 4 Pacific Ocean) (including TS Tables)4 Pacific Ocean) (including TS Tables)

Admiralty List of Radio Signals Volume 2 Admiralty List of Radio Signals Volume 2 (Radio Time Signals).(Radio Time Signals).


Standard PortsStandard Ports

List of standard ports inside front cover List of standard ports inside front cover of ATT.of ATT.

Predictions are given in the Predictions are given in the Standard Standard Time ZoneTime Zone for the country. for the country.

If necessary times must be adjusted for If necessary times must be adjusted for Daylight Saving Time (DST) usually one Daylight Saving Time (DST) usually one hour ahead of standard time.hour ahead of standard time.

Use standard tidal curve drawn for Use standard tidal curve drawn for duration between 5 and 7 hours..duration between 5 and 7 hours..


Standard Tidal CurveStandard Tidal Curve

+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


ExampleExample

Calculate the height of tide at 0900 Calculate the height of tide at 0900 on 9th April at SINGAPORE.on 9th April at SINGAPORE.

Page 2C-33 (Extract from Volume 3)Page 2C-33 (Extract from Volume 3) HW 1011 2.5m LW 0407 1.1mHW 1011 2.5m LW 0407 1.1m





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Singapore 0900

-89 Apr

1011(-8) 0407(-8) 2.5m 1.1m 1.4m

6h 04m

-



+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

1011(-8)

2.4m


Seasonal ChangesSeasonal Changes

Usually caused by meteorological trends or Usually caused by meteorological trends or effect of river water on height of tide. effect of river water on height of tide. See notes on page 2B-7.See notes on page 2B-7.ATT Standard Port predictions always ATT Standard Port predictions always include include expected seasonal changes so no expected seasonal changes so no correction is required.correction is required.When comparing the standard port When comparing the standard port predicted height with mean levels the effect predicted height with mean levels the effect of seasonal variations should be of seasonal variations should be removed.removed.



Having removed the effect of seasonal Having removed the effect of seasonal change for the standard port, the effect of change for the standard port, the effect of seasonal change must be included in the seasonal change must be included in the secondary port prediction.secondary port prediction.Tidal prediction forms (box 6) should be Tidal prediction forms (box 6) should be used to remove standard port seasonal used to remove standard port seasonal change (change sign) and include secondary change (change sign) and include secondary port change (box 11) to calculate final port change (box 11) to calculate final heights.heights.



Method is similar to European Secondary Method is similar to European Secondary Ports but time differences not Ports but time differences not interpolated.interpolated.

Use sinusoidal curves as for standard Use sinusoidal curves as for standard port.port.

Times zones do not need adjustment Times zones do not need adjustment except for Daylight Saving Time (DST).except for Daylight Saving Time (DST).

Seasonal changes are more likely and Seasonal changes are more likely and should be incorporated.should be incorporated.

Use standard tidal curve drawn for Use standard tidal curve drawn for duration between 5 and 7 hours.duration between 5 and 7 hours.


ExampleExample

Calculate at what time after 0600 Calculate at what time after 0600 local, the height of tide will first fall local, the height of tide will first fall to 2.0 metres at BROTHERS LIGHT to 2.0 metres at BROTHERS LIGHT (4766a) on 11th August?(4766a) on 11th August?


Brother’s Lt - DifferencesBrother’s Lt - DifferencesSUMATERA, NORTH EAST COAST

No PLACE TIME DIFF HEIGHT DIFF (MTRS)Lat Long MHW MLW MHWS MHWN MLWN MLWS N E (Zone –0700)

4718 SINGAPORE (see page 111) 2.8 2.1 1.2 0.5

Mandol4764 Bandong 0 32 103 18 -0007 -0007 +0.9 +0.5 +0.4 0.0

Gelam Strait4765 Tanjungbalai 0 59 103 26 -0051 -0051 +0.1 -0.1 +0.1 0.04766 Kenipaan 0 55 103 20 -0035 -0035 +0.1 +0.1 -0.2 -0.2

4766a Iyu Kecil (Brothers Light) 1 11 103 21 -0108 -0035 +0.2 +0.1 0.0 -0.1

Seasonal Changes in Mean Level

No. Jan 1 Feb 1 Mar 1 Apr 1 May 1 Jun 1 Jul 1 Aug 1 Sep 1 Oct 1 Nov 1 Dec 1

4663-4686 0.0 -0.1 -0.1 -0.1 0.0 +0.1 +0.1 0.0 0.0 0.0 0.0 0.04695 -0.1 -0.1 -0.1 -0.1 0.0 +0.1 +0.1 0.0 0.0 +0.1 +0.1 0.04704 0.0 -0.1 -0.1 -0.1 0.0 0.0 0.0 0.0 0.0 +0.1 +0.1 0.04718-4749 +0.1 0.0 0.0 0.0 0.0 0.0 -0.1 -0.1 -0.1 0.0 +0.1 +0.14751-4763 +0.1 0.0 0.0 0.0 0.0 -0.1 -0.1 -0.1 -0.1 0.0 +0.1 +0.1

4764-4783 0.0 -0.1 -0.1 0.0 0.0 0.0 0.0 0.0 0.0 +0.1 +0.1 0.04784-4795 -0.1 -0.2 -0.2 -0.1 0.0 +0.1 +0.1 +0.1 0.0 +0.1 +0.1 0.0





STANDARD PORT

TIMES HEIGHTS

HW LW HW LW RANGE

Seasonal Change

Seasonal Change

SECONDARY PORT

Duration/DST

Standard Port -

Secondary Port +

Singapore 2.0m

-711 AugBrothers Lt

1335 1935 2.6m 0.6m 2.0m

+0.1m +0.1m

-0108 -0035 +0.2m -0.1m0.0m 0.0m

1227 1900 2.9m 0.6m

6hr 33min



+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

1227(-7)

2.0m

1515(-7)


Tidal StreamsTidal Streams


Visual Evidence of StreamVisual Evidence of Stream


Sources of Tidal Stream Data Sources of Tidal Stream Data

Tidal diamonds on chartsTidal diamonds on charts Admiralty Tidal Stream AtlasesAdmiralty Tidal Stream Atlases Sailing DirectionsSailing Directions Tidal Streams in the Approaches to HM Tidal Streams in the Approaches to HM

Naval Bases (NP 167)Naval Bases (NP 167) Gibraltar Straits Surface and Sub-Gibraltar Straits Surface and Sub-

surface Water Movements (NP 629)surface Water Movements (NP 629) Admiralty Tide Tables Vol III & IVAdmiralty Tide Tables Vol III & IV


Tidal DiamondTidal Diamond

201746Z

3.3


Tidal DiamondsTidal Diamonds

Tidal Streams referred to HW at PORTSMOUTH

HoursGeographical

Position5033.9’N129.2’W

5035.9’N122.9’W

5030.4’N116.6’W

5033.5’N116.6’W

6 094 1.9 0.9 129 1.3 0.6 084 1.2 0.6 072 2.3 1.2 -65 100 2.3 1.2 127 1.7 0.9 100 3.6 1.8 070 3.7 1.8 -54 102 2.7 1.3 125 1.8 0.9 100 4.5 2.2 080 3.3 1.6 -43 101 2.5 1.2 120 1.4 0.7 100 4.5 2.2 079 2.9 1.5 -32 102 1.8 0.9 109 0.7 0.4 100 3.5 1.7 077 2.4 1.2 -21 106 0.9 0.4 320 0.6 0.3 092 1.3 0.6 066 0.3 0.1 -1

HighWater

282 0.6 0.3 302 1.8 0.9 290 1.2 0.6 262 2.4 1.2 0

1 285 1.8 0.9 300 2.1 1.1 276 3.9 1.9 257 3.4 1.7 +12 286 2.3 1.2 300 1.6 0.8 276 4.3 2.1 252 3.8 1.9 +23 281 2.2 1.1 301 0.9 0.4 276 4.1 2.0 260 3.4 1.7 +34 283 1.6 0.8 290 0.2 0.1 276 3.1 1.5 255 2.3 1.2 +45 310 0.5 0.2 135 0.5 0.2 294 1.2 0.6 247 0.8 0.4 +56 090 0.9 0.5 129 1.1 0.6 068 0.7 0.4 075 1.6 0.8 +6

Aft

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ater

Aft

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Wat

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Dir

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(d

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Ra

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Ra

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Limits Of Admiralty Tidal Limits Of Admiralty Tidal Stream AtlasesStream Atlases


Channel TS Atlas HW+2hChannel TS Atlas HW+2h


Solent TS Atlas at HWSolent TS Atlas at HW


ExampleExample What is the percentage of the Mean What is the percentage of the Mean

Spring Range and the predicted tidal Spring Range and the predicted tidal stream in position 49stream in position 49oo 50’N 001 50’N 001oo 15’W 15’W (North of Pointe de Barfleur) at 1400A (North of Pointe de Barfleur) at 1400A on 27th May?on 27th May?

Channel TS Atlas based on DoverChannel TS Atlas based on Dover

Time Height

HW HWLW LW Range

1157 6.9m1933 0.6m 6.3m

1257A 1400 is 1 hr after HW


Percentage of MSRPercentage of MSR


6.3m - 3.2m 3.1m6.0m - 3.2m 2.8m

110%


1 Hr after HW DOVER1 Hr after HW DOVER


Dover InterpolatorDover Interpolator

0 02 04 06 08 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100

0 0 2 0 4 06 08 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100

COMPUTATION OF RATESTIDAL STREAM RATE (in tenths of a knot): assumed to vary with range of the tide at Dover

MeanRangeDover

MeanRangeDover

METRES METRES

7

6

5

4

3

6.86.66.46.2

5.65.45.2

4.84.64.44.2

3.83.6

2.82.62.42.2

2

Neaps

6.86.66.46.2

5.65.45.2

4.84.64.44.2

3.83.6

2.82.62.42.2

7

6

5

4

3

2

Neaps

SpringsSprings


Calculation of RateCalculation of Rate


6.3m - 3.2m 3.1m6.0m - 3.2m 2.8m

110%

Predicted Neap Rate 1.8 kts

Predicted Spring Rate 3.5 ktsIncrease 1.7 kts

Multiply increase by percentage

1.7kt x 110% = 1.9 kts

Direction WNW Total rate 1.8 + 1.9 = 3.7 kts


NP 167 - PortsmouthNP 167 - Portsmouth


Any Questions?Any Questions?

Technology

Tides and tidal streams 1 lrg