1. Paul BrownTides – Chartwork 1 st Class Chartwork 1 st Class Tides (Adapted from RYA Shorebased slides)

2. Paul BrownTides – Chartwork 1 st Class What Causes Tides? Gravitational effects of the moon (and sun) which exert a pull on the water on the Earth's surface. What terms have you heard relating to tides? High Slack Ebb Flood Neap Range Stand Low Spring

3. Paul BrownTides – Chartwork 1 st Class TIDES Sun Earth Moon

4. Paul BrownTides – Chartwork 1 st Class TIDES - SPRINGS Earth New Moon Sun

5. Paul BrownTides – Chartwork 1 st Class TIDES - SPRINGS Earth Full Moon Sun

6. Paul BrownTides – Chartwork 1 st Class TIDES - NEAPS Earth First Quarter Neaps Sun

7. Paul BrownTides – Chartwork 1 st Class TIDES - NEAPS Sun Earth Last Quarter Neaps

8. Paul BrownTides – Chartwork 1 st Class TIDE TABLE 18 TH 0456 5.8 m 1205 1.7 m 1727 5.9 m HW LW Range 4.1 metres GMT

9. Paul BrownTides – Chartwork 1 st Class TIDE TABLE 18 TH 0556 5.8 m 1305 1.7 m 1827 5.9 m Add an hour for British Summer Time

10. Paul BrownTides – Chartwork 1 st Class TIDAL HEIGHTS - DEFINITIONS Chart Datum Charted depth (sounding) MHWS MLWS MLWN MHWN Depth of water Charted height Drying height

11. Paul BrownTides – Chartwork 1 st Class TIDAL DIAMONDS & DATUMS Tidal streams referred to HW at PLYMOUTH

12. Paul BrownTides – Chartwork 1 st Class TIDAL DIAMONDS & DATUMS 3 hours before HW Stream setting towards 318(T) Springs 2.9 kn Neaps 1.5 kn

13. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE

14. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE Look up time and height of HW Dartmouth and height of LW HW Dartmouth 1815 BST 4.8m LW 0.7m Is it Neaps or Springs? Close to Springs Use curve to find: Height of tide at Dartmouth at 1415

15. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE LW height 0.7m entered here HW height 4.8m entered here HW Dartmouth 1815 BST 4.8m LW 0.7m

16. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE HW Dartmouth 1815 BST 4.8m LW 0.7m Draw a line joining the points

17. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE HW Dartmouth 1815 BST 4.8m LW 0.7m Write time of HW in box below 1815

18. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE HW Dartmouth 1815 BST 4.8m LW 0.7m Write subsequent hours in boxes 1415 1515 1615 1715 1815

19. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE Draw vertical line from 1415 to spring curve 1415 1515 1615 1715 1815 HW Dartmouth 1815 BST 4.8m LW 0.7m

20. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE Draw horizontal line from curve to diagonal line 1415 1515 1615 1715 1815 HW Dartmouth 1815 BST 4.8m LW 0.7m

21. Paul BrownTides – Chartwork 1 st Class TIDAL CURVE Draw perpendicular to HW line 1415 1515 1615 1715 1815 Height of tide at 1415 = 2.9m

22. Paul BrownTides – Chartwork 1 st Class RULE OF TWELFTHS 1st hour 1/12 2nd hour 2/12 3rd hour 3/12 4th hour 3/12 5th hour 2/12 6th hour 1/12 HW +1h +2h +3h +4h +5h LW

23. Paul BrownTides – Chartwork 1 st Class SECONDARY PORTS National Standard Port DOVER Standard Port examples Portsmouth Plymouth (Devonport) Secondary port examples Fowey Torquay DOVER Portsmouth Flood Tide Plymouth Torquay Differences on Plymouth HW Fowey = Plymouth minus 15mins Torquay = Plymouth plus 45mins Fowey

24. Paul BrownTides – Chartwork 1 st Class SECONDARY PORTS - TIMES & HEIGHTS

25. Paul BrownTides – Chartwork 1 st Class INTERPRETING THE 'DIFFERENCES BLOCK'

26. Paul BrownTides – Chartwork 1 st Class INTERPRETING THE 'DIFFERENCES BLOCK'

27. Paul BrownTides – Chartwork 1 st Class INTERPRETING THE 'DIFFERENCES BLOCK'

28. Paul BrownTides – Chartwork 1 st Class INTERPOLATION Torquay 30th May When is HW in the morning? Standard Port Plymouth (Devonport) HW 0320 UT Difference approx +35 mins HW Torquay 0355 Time Differences (min) Torquay +0025+0030 +0045 0100 0200 0300 0400 0500 0600 +0035 +0040

29. Paul BrownTides – Chartwork 1 st Class TIDAL STREAM ATLAS Atlas gives Direction & Rate of tidal stream for each hour 4 hours after HW PORTSMOUTH

30. Paul BrownTides – Chartwork 1 st Class TIDAL STREAM ATLAS Thick and long arrows show strong stream Short and thin arrows show weak stream 4 hours after HW PORTSMOUTH

31. Paul BrownTides – Chartwork 1 st Class TIDAL STREAM ATLAS 03,05 Rate of stream 0.3 kn at Neaps 0.5 kn at Springs 12,23 Rate of stream 1.2 kn at Neaps 2.3 kn at Springs Stream Slack