1. Tidal Streams- Horizontal movement of tides
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International Sailing Navnotes c

2. International Sailing Navnotes c
Tidal Streams
As earth rotates gravitational pull of moon causes a wave to move in from the west – this is the flood
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International Sailing Navnotes c

3. International Sailing Navnotes c
Tidal Streams
As earth rotates gravitational pull of moon causes a wave to move in from the west – this is the flood
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International Sailing Navnotes c

4. International Sailing Navnotes c
Tidal Streams
The tide ebbs in the opposite direction
Tidal streams are affected by geographical features
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International Sailing Navnotes c

5. International Sailing Navnotes c
Tidal Streams- info
Arrows on charts
Tidal Stream Atlas
Tidal Diamonds
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International Sailing Navnotes c

6. Tidal Streams - Arrows on charts
Arrow with feathers is flood
without is ebb
Found on Irish charts
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International Sailing Navnotes c

7. of tidal stream for each hour
TIDAL STREAM ATLAS
Atlas gives
Direction & Rate
of tidal stream for each hour
4 hours after
HW PORTSMOUTH
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International Sailing Navnotes c

8. TIDAL STREAM ATLAS Short and thin arrows show weak stream
Thick and long arrows show strong stream
Short and thin arrows show weak stream
4 hours after
HW PORTSMOUTH
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International Sailing Navnotes c

9. International Sailing Navnotes c
TIDAL STREAM ATLAS
03,05
Rate of stream
0.3 kn at Neaps
0.5 kn at Springs
12,23
1.2 kn at Neaps
2.3 kn at Springs
Stream
Slack
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International Sailing Navnotes c

10. Tidal Streams – tidal stream atlas
Page for each hour Arrow for direction
Neap speed 13= then spring speed 21= 2.1
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International Sailing Navnotes c

11. Tidal Streams- Diamonds
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International Sailing Navnotes c

12. TIDAL DIAMONDS & DATUMS
3 hours before HW
Stream setting towards 318(T)
Springs
2.9 kn
Neaps
1.5 kn
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International Sailing Navnotes c

13. HOURS RELATED TO HIGH WATER
Time of High Water = 1200 HW
____________________________________
0930
1030
1130
1230
1330
HW - 2
HW - 1 HW
HW + 1
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International Sailing Navnotes c

14. International Sailing Navnotes c
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International Sailing Navnotes c

15. TIDAL STREAM RATE (in tenths of a knot)
COMPUTATION OF RATES
Mean Range
PLYMOUTH
Neaps 5m 4m 3m 2m 1m
Springs 6m 20 30 10 40 50 60 70
TIDAL STREAM RATE (in tenths of a knot)
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International Sailing Navnotes c

16. Rate of stream at Neaps = 2.3 knots
Tenths of a Knot
COMPUTATION OF RATES
Mean Range PLYMOUTH
Neaps 5m 4m 3m 2m 1m
Springs 6m 20 30 10 40 50 60 70
TIDAL STREAM RATE (in tenths of a knot)
Rate of stream at Neaps = 2.3 knots
(from tidal stream atlas or diamonds)
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International Sailing Navnotes c

17. Rate of stream at Springs = 4.6 knots
Tenths of a Knot
COMPUTATION OF RATES
Mean Range
PLYMOUTH
Neaps 5m 4m 3m 2m 1m
Springs 6m 20 30 10 40 50 60 70
TIDAL STREAM RATE (in tenths of a knot)
Rate of stream at Springs = 4.6 knots
(from tidal stream atlas or diamonds)
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International Sailing Navnotes c

18. TIDAL STREAM RATE (in tenths of a knot)
COMPUTATION OF RATES
Mean Range
PLYMOUTH
Neaps 5m 4m 3m 2m 1m
Springs 6m 20 30 10 40 50 60 70
TIDAL STREAM RATE (in tenths of a knot)
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International Sailing Navnotes c

19. TIDAL STREAM RATE (in tenths of a knot)
COMPUTATION OF RATES
Mean Range
PLYMOUTH
Neaps 5m 4m 3m 2m 1m
Springs 6m 20 30 10 40 50 60 70
TIDAL STREAM RATE (in tenths of a knot)
Today’s Range 4.2m
Rate = 4.1 knots
28/04/2019
International Sailing Navnotes c