Tides and Tidal
Streams
A brief by Lance Grindley
Using Admiralty Tidal
Publications
Grunt Productions 2006
“Everyone can just put down their loot and plunder
- Sven here has something to say to us all!”
Grunt Productions 2006
NWC Assessment



Award of MCA certification is subject to
successful completion of written
examination in “Tides and Times”.
Criteria for evaluating competence “Calculations and measurement of
navigational information are accurate.”
Use Tide Tables to work out height of
tide at any place or time a chosen
height is achieved.
Grunt Productions 2006
Range of Lesson




Calculating heights and depths from
levels and datums.
Calculating predicted heights for any
Standard Port (European and NonEuropean)
Calculating predicted heights for
European and Non-European Secondary
Ports (including Solent)
Calculating tidal streams using tidal
diamonds and Tidal Stream Atlases
Grunt Productions 2006
Introduction
Basic principles of tides.
The tide raising forces of
the Moon and the Sun.
Grunt Productions 2006
The Earth-Moon System
Gravitational
Attraction
Barycentre
Moon
Earth
Grunt Productions 2006
Daily Tidal Period
+ 6 hours
+ 25 hours
+ 12 hours
+Start
24 hours
- HW
+ 18 hours
Earth
Grunt Productions 2006
Moon
Tidal Period




The Lunar Day lasts just under 25
hours.
In each period of 24 hours there will
be two HW and two LW.
Each HW and LW will occur
approximately 6 hours 10 minutes
after each other.
The predicted times of HW and LW get
progressively later each day by about
one hour.
Grunt Productions 2006
The Sun-Moon System
New Moon
Lunar Tide
Moon
Earth
Grunt Productions 2006
Solar Tide
The Sun-Moon System
Full Moon
Moon
Earth
Grunt Productions 2006
The Sun-Moon System
First/Last Quarter
Moon
Earth
Grunt Productions 2006
Moon
Spring and Neap Tides




In each Lunar Month there will be a New
Moon and a Full Moon.
At this period the range will be a
maximum range which is called a Spring
Tide.
The Moon will also pass two period of
quadrature and the range will be a
minimum which is called a Neap Tide.
Tides of this pattern are called SemiDiurnal Tides and occur throughout the
Atlantic region.
Grunt Productions 2006
Tidal Prediction
Admiralty Tide Tables (4 volumes)

Volume 1 UK and Channel Coast

Volume 2 European and Atlantic
Waters

Volume 3 Indian Ocean

Volume 4 Pacific Ocean.

Grunt Productions 2006
Limits of Tide Tables
Grunt Productions 2006
Heights and Datums




All depths and drying heights are
measured from the Chart Datum.
Chart Datum is usually set at LAT
Tidal levels LAT, MLWS, MLWN, MSL,
MHWN, MHWS and HAT are given as
heights above Chart Datum.
All heights are measured from MHWS.
Grunt Productions 2006
DATUM FOR HEIGHTS
Tidal
Levels
and
Datums
Grunt Productions 2006
LAND LEVELLING
DATUM
DATUM FOR DEPTHS
Tidal Datums
HAT
MHWS
MLWS
LAT
Grunt Productions 2006
MHWN
MLWN
MSL
Chart Datum
Mean Spring Range
MHWS
Mean Spring Range
MLWS
Chart Datum
Grunt Productions 2006
Charted Height
Height
above
waterline
Charted
Height
MHWS
Height of Tide
Chart Datum
Grunt Productions 2006
Height of MHWS
above Chart
Datum
Underkeel Clearance
Height
of Tide
Charted Depth
Grunt Productions 2006
Draught
Chart Datum
Tide + Depth - Draught
Minimum Clearance 2m
Minimum
Height of Tide
Charted Depth
Grunt Productions 2006
Draught
Chart Datum
2m minimum
Masthead Clearance
Masthead Clearance
Masthead
Height
Maximum
Height of Tide
Grunt Productions 2006
Charted Height
MHWS
Chart Datum
Example







Port of MILFORD HAVEN
Power cable with charted height 24m
Minimum charted depth 4m
Vessel details: - masthead height
22m
- draught 6m.
Clearances:
- masthead 3m
- underkeel 2m
Grunt Productions 2006
Diagram
Cable
3m
24m
22m
MHWS
7m
6m
6m
HoT Chart Datum
4m
4m
2m
Grunt Productions 2006
Seabed
Max/min height of tide




Minimum HoT = 6m+2m-4m = 4
metres
Maximum HoT = 24m+7m(22m+3m)
31m - 25m = 6
metres
Height of tide must lie between 4
and 6 metres
Grunt Productions 2006
The Tidal Curve
Height
of
Tide
Predicted Height
Range of
Tide
Rise of
Tide
Height
of Tide
Interval
Chart
Datum
LW
Grunt Productions 2006
Duration
HW
LW
Time
Express Range as Percentage




Difference between the Mean Neap
Range and the Mean Spring Range is
100%.
Any range can be expressed as a
percentage increase from the MNR.
Example (Portsmouth) MSR 3.9m MNR
1.9m
Difference of 2.0m represents 100%
Springs
Range of 3.0m is 3.0-1.9/2.0 =
1.1/2.0 = 55%
Grunt Productions 2006

Hourly Predictions



Found in ATT Volume 1 Part 1a
Eight ports are included:
Plymouth; Poole Harbour;
Southampton; Portsmouth;
Rosyth; Liverpool; Avonmouth;
St. Helier
Grunt Productions 2006
European Ports
Grunt Productions 2006
Publications



Admiralty Tide Tables Volume 1
(United Kingdom and Ireland)
(Including European Channel Ports).
Admiralty Tides Tables Volume 2
(Europe excluding United Kingdom
and Ireland) Mediterranean Sea and
Atlantic Ocean.
Admiralty List of Radio Signals
Volume 2 (Radio Time Signals).
Grunt Productions 2006
Standard Ports




List of ports inside front cover of ATT.
Predictions are given in the Official
Standard Time for the country. (This
happens to be Universal Time in the United
Kingdom.)
If necessary times must be adjusted for
Daylight Saving Time (DST) usually one
hour ahead of standard time.
First page of standard port predictions will
be the tidal curve unique to that port.
Grunt Productions 2006
Tidal Curve - Dover
0
2
4
6
DOVER
8
MEAN RANGES
Springs 6.0m
Neaps 3.2m
0
2
4
Grunt Productions 2006
6
-5
-4
-3
-2
-1
HW +1
+2
+3
+4
+5
+6
Tidal Curve - Southampton
0
1
2
3
SOUTHAMPTON
4
MEAN RANGES
Springs 4.0m
Neaps 1.9m
0
1
2
Grunt Productions 2006
3
-5
-4
-3
-2
-1
LW
+1
+2
+3
+4
+5
+6
Tidal Prediction Form
STANDARD PORT……………………TIME/HEIGHT REQUIRED…………
SECONDARY PORT…………………..DATE…..……….TIME ZONE……...
TIMES
STANDARD PORT
HW
LW
Seasonal Change
Standard Port -
Seasonal Change
Secondary Port +
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
HW
LW
RANGE
Portsmouth Predictions
ENGLAND - PORTSMOUTH
Lat 50°48’N Long 1°07’W
TIME ZONE UT (GMT) TIMES AND HEIGHTS OF HIGH AND LOW WATERS YEAR 1998
JUNE
1
M
2
TU
3
W
4
TH
5
F
6
TU
Grunt Productions 2006
Time
0338
0911
1819
2140
m
4.1
1.4
4.1
1.7
0427
1008
1715
2244
3.9
1.6
4.0
1.8
17
0527
1114
1819
2354
3.7
1.8
3.9
1.9
18
0638
1221
1924
3.7
1.8
4.0
19
0058
0746
1320
2019
1.8
3.8
1.7
4.1
20
0151
0841
1408
2105
1.6
3.9
1.5
4.2
21
16
F
SA
SU
M
SA
SU
JULY
Time
0301
0838
1543
2109
m
4.3
1.1
4.4
1.3
0356
0937
1641
2213
4.2
1.3
4.3
1.4
2
0459
1044
1747
2324
4.1
1.3
4.3
1.5
3
0609
1157
1857
4.1
1.3
4.3
4
0037
0722
1307
2003
1.4
4.2
1.2
4.5
5
0144
0830
1409
2103
1.2
4.3
1.1
4.6
6
1
M
TU
W
TH
F
SA
Time
0458
1144
1723
m
0.8
4.8
0.6
0015
0539
1227
1803
4.8
0.8
4.7
0.6
0056
0618
1306
1840
4.7
0.8
4.7
0.7
18
0133
0654
1343
1914
4.7
0.9
4.5
0.8
19
0208
0728
1419
1946
4.6
1.1
4.4
1.0
20
0243
0802
1455
2019
4.5
1.3
4.2
1.2
21
16
TU
•
17
W
TH
F
SA
SU
Time
0435
1119
1657
2347
m
0.9
4.6
0.7
4.7
0515
1200
1738
0.8
4.6
0.6
0027
0555
1242
1817
4.7
0.6
4.7
0.5
0108
0635
1324
1857
4.8
0.6
4.7
0.5
0150
0716
1407
1939
4.8
0.6
4.7
0.6
0233
0800
1452
2023
4.7
0.8
4.5
0.8
Tidal Prediction Form
Portsmouth
1100
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
5 June
A
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
HW
LW
HW
LW
RANGE
0746
1320
3.8m
1.7m
2.1m
Seasonal Change
Standard Port -
Seasonal Change
Secondary Port +
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
0846A
10% Sp
Tidal Curve - Portsmouth
HW
3.3m
3.8m
0
1
2
3
4
PORTSMOUTH
5
MEAN RANGES
Springs 3.9m
Neaps 1.9m
0
1
LW 1.7m
2
Grunt Productions 2006
3
-6
-5
-4
-3
-2
-1
HW
0846A
+1
+2
+3
1100A
+4
+5
Secondary Ports





Times and heights are obtained by
applying time and height differences to
Standard Port predictions.
Obtain Port Number from Geographical
Index at back of ATT.
Use Part II (page 300-323) to obtain:
Standard Port
Secondary Port time Zone

Grunt Productions 2006
Secondary Port differences.
Example


Find out what time the height of tide
will first rise to 5.0 metres at
WATCHET (531) on 26th July, 1989.
Page 2A-102 for Secondary Port
Differences.
Grunt Productions 2006
Secondary Port Differences
WALES; ENGLAND, WEST COAST
No
PLACE
Lat
N
Long
W
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
523 PORT OF BRISTOL
(AVONMOUTH) …(see page 158)
0200
and
1400
0800
and
2000
0300
and
1500
0800
and
2000
13.2
9.8
3.8
1.0
531 Watchet
-0035
-0050
-0145
-0040
-1.9
-1.5
+0.1
+0.1
Grunt Productions 2006
51 11
3 20
Tidal Prediction Form
Avonmouth
5.0m
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
Watchet
26 Jul
A
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
HW
LW
HW
LW
RANGE
0858
0328
12.8m
1.1m
11.7m
Seasonal Change
Standard Port -
Seasonal Change
Secondary Port +
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
92% Sp
High Water Differences
WALES; ENGLAND, WEST COAST
No
PLACE
Lat
N
Long
W
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
523 PORT OF BRISTOL
(AVONMOUTH) …(see page 158)
0200
and
1400
0800
and
2000
0300
and
1500
0800
and
2000
13.2
9.8
3.8
1.0
531 Watchet
-0035
-0050
-0145
-0040
-1.9
-1.5
+0.1
+0.1
51 11
3 20
1400 - 0858 - 0800
-0035
-0050
-48 min
Grunt Productions 2006
Interpolation of HW Times
Times of HW at Bristol
0800
0900
1000
1100
1200
1300
1400
-38m
-35 min
Watchet Differences
-50 min
Grunt Productions 2006
-48m
-45m
-
-43m
-40m
Low Water Differences
WALES; ENGLAND, WEST COAST
No
PLACE
Lat
N
Long
W
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
523 PORT OF BRISTOL
(AVONMOUTH) …(see page 158)
0200
and
1400
0800
and
2000
0300
and
1500
0800
and
2000
13.2
9.8
3.8
1.0
531 Watchet
-0035
-0050
-0145
-0040
-1.9
-1.5
+0.1
+0.1
51 11
3 20
0300 - 0328 - 0800
-0145
-0040
-0138
Grunt Productions 2006
Interpolation of LW Times
Times of LW at Bristol
0300
0400
0500
0600
0700
0800
Watchet Differences
-105m
Grunt Productions 2006
-92m
-79m
-
-66m
-53m
-40m
High Water Correction
WALES; ENGLAND, WEST COAST
No
PLACE
Lat
N
Long
W
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
523 PORT OF BRISTOL
(AVONMOUTH) …(see page 158)
0200
and
1400
0800
and
2000
0300
and
1500
0800
and
2000
13.2
9.8
3.8
1.0
531 Watchet
-0035
-0050
-0145
-0040
-1.9
-1.5
+0.1
+0.1
51 11
3 20
12.8m
Grunt Productions 2006
13.2m
9.8m
-1.9m
-1.5m
13.2m
12.4m
11.5m
10.7m
9.8m
-1.9m
-1.8m
-1.7m
-1.6m
-1.5m
Low Water Correction
WALES; ENGLAND, WEST COAST
No
PLACE
Lat
N
Long
W
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
523 PORT OF BRISTOL
(AVONMOUTH) …(see page 158)
0200
and
1400
0800
and
2000
0300
and
1500
0800
and
2000
13.2
9.8
3.8
1.0
531 Watchet
-0035
-0050
-0145
-0040
-1.9
-1.5
+0.1
+0.1
51 11
3 20
1.1m
Grunt Productions 2006
Tidal Prediction Form
Avonmouth
5.0m
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
Watchet
26 Jul
A
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
Seasonal Change
HW
LW
HW
LW
RANGE
0858
0328
12.8m
1.1m
11.7m
Standard Port -0048
Seasonal Change
-0138
92% Sp
-1.9m
+0.1m
Secondary Port +
SECONDARY PORT
0810Z
Duration/DST
0910A
Grunt Productions 2006
HEIGHTS
0150Z
10.9m
1.2m
Tidal Curve - Avonmouth
0
2
4
6
8
10
12
14
AVONMOUTH
MEAN RANGES
Springs 12.2m
Neaps
6.0m
0
2
4
Grunt Productions 2006
6
-5
-4
-3
0550A
-2
-1
HW +1
0910A
+2
+3
+4
+5
+6
Solent Ports
Times and heights are obtained by
applying time and height
differences to PORTSMOUTH.
 All ports 37 to 70 are listed on
pages 323/324 (2A-90).
 Curves listed on pages xxii to xxiv
using separate curves for each
group of ports.
 Curves are based on Low Water.
 Obtain differences in the normal
Grunt Productions
2006
way.

Stansore Point Curve
0
1
2
3
4
5
-7
-6
-5
-4
Bucklers Hard
Stansore Point
Lee
Folly Inn
Newport
0
1
2
Grunt Productions 2006
3
4
5
-3
-2
-1
LW +1 +2 +3 +4 +5 +6 +7
Range at Portsmouth
Sp
3.9m
Np
1.9m
Lymington/Yarmouth Curve
0
1
2
3
4
5
-7
-6
-5
Lymington
Yarmouth
0
1
2
Grunt Productions 2006
3
4
5
-4
-3
-2
-1
LW +1 +2 +3 +4 +5 +6 +7
Range at Portsmouth
Sp
3.9m
2.6m
Np
1.9m
Example


What time will the height of tide first
rise to 3.0 metres at STANSORE
POINT on 2 June?
Portsmouth predictions LW 2140
1.7m, HW 0427 3.9m
Grunt Productions 2006
Tidal Prediction Form
Portsmouth
3.0m
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
Stansore Pt
2 Jun
A
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
HW
LW
HW
LW
RANGE
0427Z
2140Z
3.9m
1.7m
2.2m
Seasonal Change
Standard Port -
Seasonal Change
Secondary Port +
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
15%Sp
Solent Port Differences
ENGLAND, SOUTH COAST
No
PLACE
Lat
N
Long
W
65 PORTSMOUTH
TIME DIFFERENCES
High Water
Low Water
Zone UT (GMT)
0000
and
1200
0600
and
1800
0500
and
1700
HEIGHT DIFF (METRES)
MHWS MHWN MLWN MLWS
1100
and
2300
4.7
3.8
1.9
0.8
37 Bournemouth
38 Christchurch
50 43
50 43
1 52
1 45
-0240
-0230
+0055 -0050
+0030 -0035
-0030
-0035
-2.7
-2.9
-2.2
-2.4
-0.8
-1.2
-0.3
-0.2
39 Hurst Point
40 Lymington
43 Stansore Point
50 42
50 46
50 47
1 33
1 32
1 21
-0115
-0110
-0050
-0005 -0030
+0005 -0020
-0010 -0005
-0025
-0020
-0010
-2.0
-1.7
-0.9
-1.5
-1.2
-0.6
-0.5
-0.5
-0.2
-0.1
-0.1
-0.0
Isle of Wight
45 Yarmouth
46 Totland Bay
48 Freshwater
50 42
50 41
50 40
1 30
1 33
1 31
-0105
-0130
-0210
+0005 -0025
-0045 -0040
+0025 -0040
-0030
-0040
-0020
-1.6
-2.0
-2.1
-1.3
-1.5
-1.5
-0.4
-0.5
-0.4
0.0
0.1
0.0
51 Ventnor
53 Sandown
53a Foreland (Slip)
54 Bembridge Hbr
58 Ryde
50 36
50 39
50 41
50 42
50 44
1 12
1 09
1 04
1 06
1 07
-0025
0000
-0005
-0010
-0010
-0030
+0005
0000
+0005
+0010
-0030
+0025
+0010
0000
-0010
-0.8
-0.6
-0.1
-1.6
-0.2
-0.6
-0.5
-0.1
-1.5
-0.1
-0.2
-0.2
0.0
-1.4
0.0
+0.2
0.0
+0.1
-0.6
+0.1
Grunt Productions 2006
-0025
=0010
+0005
+0020
-0005
Interpolation of HW Times
0000
Times of HW at Portsmouth
0427
0100
0200
0300
0400
0500
0600
Stansore Point Differences
-50 min
-43m
-37m
-
-30m
-23m
-17m
-20m
Grunt Productions 2006
-10 min
Tidal Prediction Form
Portsmouth
3.0m
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
Stansore Pt
2 Jun
A
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
Seasonal Change
HW
LW
HW
LW
RANGE
0427Z
2140Z
3.9m
1.7m
2.2m
Standard Port -0020
Seasonal Change
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
-0009
-0.6m
-0.2m
3.3m
1.5m
Secondary Port +
0407Z
2131Z
2231A
15%Sp
Stansore Point Curve
0415A
0
1
2
3
4
5
-7
-6
-5
-4
-3
-2
-1
LW +1 +2 +3 +4 +5 +6 +7
Bucklers Hard
Stansore Point
Lee
Folly Inn
Newport
0
1
2
Grunt Productions 2006
3
4
5
Range at Portsmouth
Sp
3.9m
Np
1.9m
2231A
Non-European Ports
Grunt Productions 2006
Publications



Admiralty Tides Tables Volume 2
(Europe excluding United Kingdom and
Ireland) Mediterranean Sea and Atlantic
Ocean.
Admiralty Tide Tables Volume 3 (Indian
Ocean and South China Sea) & Volume
4 Pacific Ocean) (including TS Tables)
Admiralty List of Radio Signals Volume
2 (Radio Time Signals).
Grunt Productions 2006
Standard Ports




List of standard ports inside front cover
of ATT.
Predictions are given in the Standard
Time Zone for the country.
If necessary times must be adjusted for
Daylight Saving Time (DST) usually one
hour ahead of standard time.
Use standard tidal curve drawn for
duration between 5 and 7 hours..
Grunt Productions 2006
Standard Tidal Curve
0
0
2
1
4
2
6
3
8
4
0
0
1
2
2
4
3
6
-7
Grunt Productions 2006
10
5
-6
-5
12
6
-4
14
7
-3
-2
-1
HW +1
+2
+3
+4
+5
+6
+7
Example



Calculate the height of tide at 0900
on 9th April at SINGAPORE.
Page 2C-33 (Extract from Volume 3)
HW 1011 2.5m LW 0407 1.1m
Grunt Productions 2006
Tidal Prediction Form
Singapore
0900
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
9 Apr
-8
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
HW
LW
HW
LW
1011(-8)
0407(-8)
2.5m
1.1m
Seasonal Change
Standard Port -
Seasonal Change
Secondary Port +
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
6h 04m
RANGE
1.4m
Standard Tidal Curve
0
0
2
1
4
6
22.4m 3
8
4
0
0
1
2
2
4
-7
Grunt Productions 2006
3
6
10
5
-6
-5
12
6
-4
14
7
-3
-2
-1
HW +1
1011(-8)
+2
+3
+4
+5
+6
+7
Seasonal Changes
Usually caused by meteorological trends or
effect of river water on height of tide.
See notes on page 2B-7.
ATT Standard Port predictions always
include expected seasonal changes so no
correction is required.
When comparing the standard port
predicted height with mean levels the effect
of seasonal variations should be removed.

Grunt Productions 2006
Secondary Ports
Having removed the effect of seasonal
change for the standard port, the effect of
seasonal change must be included in the
secondary port prediction.
Tidal prediction forms (box 6) should be
used to remove standard port seasonal
change (change sign) and include secondary
port change (box 11) to calculate final
heights.

Grunt Productions 2006
Secondary Ports
Method is similar to European
Secondary Ports but time differences
not interpolated.
 Use sinusoidal curves as for standard
port.
 Times zones do not need adjustment
except for Daylight Saving Time (DST).
 Seasonal changes are more likely and
should be incorporated.
 Use standard tidal curve drawn for
Grunt Productions 2006
duration between 5 and 7 hours.

Example

Calculate at what time after 0600
local, the height of tide will first fall
to 2.0 metres at BROTHERS LIGHT
(4766a) on 11th August?
Grunt Productions 2006
Brother’s Lt - Differences
SUMATERA, NORTH EAST COAST
No
PLACE
Lat
N
Long
E
4718 SINGAPORE
(see page 111)
Mandol
4764 Bandong
0 32
Gelam Strait
4765 Tanjungbalai
4766 Kenipaan
4766a Iyu Kecil (Brothers Light)
TIME DIFF
MHW MLW
(Zone –0700)
HEIGHT DIFF (MTRS)
MHWS MHWN MLWN MLWS
2.8
2.1
1.2
0.5
103 18 -0007
-0007 +0.9
+0.5
+0.4
0.0
0 59
0 55
103 26 -0051
103 20 -0035
-0051 +0.1
-0035 +0.1
-0.1
+0.1
+0.1
-0.2
0.0
-0.2
1 11
103 21 -0108
-0035 +0.2
+0.1
0.0
-0.1
Seasonal Changes in Mean Level
No.
Jan 1
4663-4686 0.0
4695
-0.1
4704
0.0
4718-4749 +0.1
4751-4763 +0.1
Feb 1
Mar 1
Apr 1
-0.1
-0.1
-0.1
0.0
0.0
-0.1
-0.1
-0.1
0.0
0.0
-0.1
-0.2
Grunt Productions
2006
4764-4783 0.0
-0.1
4784-4795 -0.1
-0.2
May 1
Jun 1
Jul 1
Aug 1
Sep 1
Oct 1
Nov 1
Dec 1
-0.1
-0.1
-0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
+0.1
+0.1
0.0
0.0
-0.1
+0.1
+0.1
0.0
-0.1
-0.1
0.0
0.0
0.0
-0.1
-0.1
0.0
0.0
0.0
-0.1
-0.1
0.0
+0.1
+0.1
0.0
0.0
0.0
+0.1
+0.1
+0.1
+0.1
0.0
0.0
0.0
+0.1
+0.1
0.0
-0.1
0.0
0.0
0.0
+0.1
0.0
+0.1
0.0
+0.1
0.0
0.0
+0.1
+0.1
+0.1
+0.1
0.0
0.0
Tidal Prediction Form
Singapore
2.0m
STANDARD PORT……………………TIME/HEIGHT
REQUIRED…………
Brothers Lt
11 Aug
-7
SECONDARY PORT…………………..DATE…..……….TIME
ZONE……...
TIMES
STANDARD PORT
Seasonal Change
HW
LW
HW
LW
RANGE
1335
1935
2.6m
0.6m
2.0m
+0.1m
+0.1m
Standard Port -
-0108
Seasonal Change
SECONDARY PORT
Duration/DST
Grunt Productions 2006
HEIGHTS
-0035
Secondary Port +
1227
1900
6hr 33min
+0.2m
-0.1m
0.0m
0.0m
2.9m
0.6m
Standard Tidal Curve
0
0
2
1
4
6
22.0m 3
8
4
10
5
12
6
14
7
1515(-7)
0
0
1
2
2
4
Grunt Productions 2006
3
6
-7
-6
-5
-4
-3
-2
-1
HW +1
1227(-7)
+2
+3
+4
+5
+6
+7
Tidal Streams
Grunt Productions 2006
Visual Evidence of Stream
Grunt Productions 2006
Sources of Tidal Stream Data






Tidal diamonds on charts
Admiralty Tidal Stream Atlases
Sailing Directions
Tidal Streams in the Approaches to HM
Naval Bases (NP 167)
Gibraltar Straits Surface and Subsurface Water Movements (NP 629)
Admiralty Tide Tables Vol III & IV
Grunt Productions 2006
Tidal Diamond
3.3
201746Z
Grunt Productions 2006
Tidal Diamonds
Tidal Streams referred to HW at PORTSMOUTH
Grunt Productions 2006
Rates at neap tides (knots)
Rates at spring tides (knots)
Directions of streams (degrees)
After High
Water
After Low
Water
Hours
6
5
4
3
2
1
High
Water
1
2
3
4
5
6
Geographical
Position
094
100
102
101
102
106
50°
33.9’N
1°
29.2’W
1.9 0.9
2.3 1.2
2.7 1.3
2.5 1.2
1.8 0.9
0.9 0.4
282
285
286
281
283
310
090
D
129
127
125
120
109
320
50°
35.9’N
1°
22.9’W
1.3 0.6
1.7 0.9
1.8 0.9
1.4 0.7
0.7 0.4
0.6 0.3
0.6 0.3
302
1.8
2.3
2.2
1.6
0.5
0.9
300
300
301
290
135
129
0.9
1.2
1.1
0.8
0.2
0.5
E
084
100
100
100
100
092
50°
30.4’N
1°
16.6’W
1.2 0.6
3.6 1.8
4.5 2.2
4.5 2.2
3.5 1.7
1.3 0.6
1.8 0.9
290
2.1
1.6
0.9
0.2
0.5
1.1
276
276
276
276
294
068
1.1
0.8
0.4
0.1
0.2
0.6
F
072
070
080
079
077
066
50°
33.5’N
1°
16.6’W
2.3 1.2
3.7 1.8
3.3 1.6
2.9 1.5
2.4 1.2
0.3 0.1
-6
-5
-4
-3
-2
-1
1.2 0.6
262
2.4 1.2
0
3.9
4.3
4.1
3.1
1.2
0.7
257
252
260
255
247
075
3.4
3.8
3.4
2.3
0.8
1.6
1.9
2.1
2.0
1.5
0.6
0.4
G
1.7
1.9
1.7
1.2
0.4
0.8
+1
+2
+3
+4
+5
+6
Limits Of Admiralty Tidal
Stream Atlases
Grunt Productions 2006
Channel TS Atlas HW+2h
Grunt Productions 2006
Solent TS Atlas at HW
Grunt Productions 2006
Example


What is the percentage of the Mean
Spring Range and the predicted tidal
stream in position 49o 50’N 001o 15’W
(North of Pointe de Barfleur) at 1400A
on 27th May?
Channel TS Atlas based on Dover
Time
Height
HW
LW
HW
LW
Range
1157
1933
6.9m
0.6m
6.3m
1257A
Grunt Productions 2006
1400 is 1 hr after HW
Percentage of MSR
MEAN RANGES
Springs 6.0m
Neaps 3.2m
6.3m - 3.2m
6.0m - 3.2m
3.1m
2.8m
110%
Grunt Productions 2006
1 Hr after HW DOVER
Grunt Productions 2006
Dover Interpolator
Mean
Range
Dover
COMPUTATION OF RATES
TIDAL STREAM RATE (in tenths of a knot): assumed to vary with range of the tide at Dover
METRES
Mean
Range
Dover
METRES
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
7
6.8
6.6
6.4
6.2
6
Springs
6.8
6.6
6.4
6.2
5.6
5.4
5.2
54.8
4.6
4.4
4.2
5.6
5.4
5.2
3.8
3.6
3.6
Neaps
5
4
Neaps
32.8
2.8
2.6
2.4
2.2
2.6
2.4
2.2
2
6
Springs
4.8
4.6
4.4
4.2
43.8
7
Grunt Productions 2006
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
3
2
Calculation of Rate
MEAN RANGES
Springs 6.0m
Neaps 3.2m
6.3m - 3.2m
6.0m - 3.2m
Predicted Neap Rate 1.8 kts
Predicted Spring Rate 3.5 kts
3.1m
2.8m
110%
Increase 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
Grunt Productions 2006
NP 167 - Portsmouth
Grunt Productions 2006
Any Questions?
Grunt Productions 2006