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  • Introduction
    • 0.0.1 Warning
    • 0.1 Layout reference
      • 0.1.1 Highlight:
      • 0.1.2 Examples:
      • 0.1.3 Extra info:
      • 0.1.4 External links
    • 0.2 Copyright and permissions
  • 1 Maps and charts
    • 1.1 Maps and Charts
      • 1.1.1 Comparing maps and charts
      • 1.1.2 Which to use?
      • 1.1.3 Obtaining maps and charts
    • 1.2 Specifying position
    • 1.3 Latitude and longitude
    • 1.4 The units of the sea
      • 1.4.1 Distances and speeds
    • 1.5 The compass
    • 1.6 Reading charts
    • 1.7 Navigational marks
    • 1.8 Practicalities
      • 1.8.1 On the water
      • 1.8.2 On dry land
  • 2 Tides
    • 2.1 Introducing tides
      • 2.1.1 The moon
      • 2.1.2 The Sun - neaps and springs
    • 2.2 Tide tables
    • 2.3 Predicting high and low water
    • 2.4 Tidal range
    • 2.5 Tidal streams
    • 2.6 Behavior of tidal streams
    • 2.7 Tidal diamonds
    • 2.8 Tidal stream atlases
    • 2.9 Pilots and guidebooks
    • 2.10 Predicting speeds of tidal streams
    • 2.11 Variation of flow through the tidal cycle
      • 2.11.1 50/90 rule
      • 2.11.2 Rule of thirds
    • 2.12 Formal navigation for short crossings
  • 3 Weather
    • 3.1 Forecasts
    • 3.2 Effects of weather on the sea
      • 3.2.1 Wind against tide
      • 3.2.2 Offshore winds
      • 3.2.3 Cross seas / Confused seas
      • 3.2.4 Reflected waves, clapotis
      • 3.2.5 Wave diffraction and focusing
      • 3.2.6 Boomers
    • 3.3 Air masses
    • 3.4 Global circulation
    • 3.5 Depressions
    • 3.6 Synoptic charts
    • 3.7 High pressure
    • 3.8 Depressions in practice
    • 3.9 Localized effects
      • 3.9.1 Sea breezes
      • 3.9.2 Anabatic and katabatibc winds
      • 3.9.3 Fog
  • 4 Pilotage
    • 4.1 Coastal pilotage
      • 4.1.1 Distance, speed and time
      • 4.1.2 Dead reckoning
      • 4.1.3 Compass use for coastal pilotage
    • 4.2 Signs of tidal flow
    • 4.3 Transits
    • 4.4 Fixes
    • 4.5 Low visibility navigation
      • 4.5.1 Short legs
      • 4.5.2 Aiming off
      • 4.5.3 Attack points

Notes on Sea Kayak Navigation and Tidal Planning

0.2 Copyright and permissions

One of the challenges in teaching tidal planning and navigation is giving students access to realistic materials without spending lots of money or infringing copyright. Fortunately, using online tools overcomes some of these problems, by enabling me to make use of:

  • OS maps supplied by BING See terms. Because Bing maps use a different projection to the Ordnance Survey, these maps will appear tilted from their normal orientation.
  • My home-made time tables - these are based on Environment Agency tide gauge data from the real-time data API (Beta) (public sector information licensed under the Open Government Licence v3.0) and created using Wesley Bowman’s Python implementation of UTide.

I also make use of some other resources:

  • Admiralty pilots that are sufficiently old that the Crown Copyright has expired.
  • Admiralty charts (0034 Isles of Scilly & 1971 Cardigan Bay Northern Part), licensed from the UKHO (license number 36411).
  • US government materials and publications (the US government does not enforce copyright on these)
  • Small extracts from copyrighted materials (e.g. sea kayak guidebooks) for the purpose of review - I believe this constitutes ‘fair use’, and where such materials are used, I include a clear reference to the materials, normally with a strong endorsement of them!
  • Some UK government materials, licensed under the Open Government License.
  • Holmes, Ian. (2017). Mean High Water Springs Polygon, [Dataset]. University of Edinburgh. https://doi.org/10.7488/ds/1969, licensed under the Open Government License. These data are used as a basis for simple map diagrams.
  • Images taken or made by myself or those I paddle with - thanks especially to Alison and Joe for the stunning images!

The material on this site is subject to copyright, and may not be used without permission. However, you are free to use it for teaching kayaking on a non-commercial basis. Please do contact me if you’d like to make use of it for other purposes (rbown (at) cantab (dot) net) - generally, I’m happy that my work can be useful to people!