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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 Weather
    • 1.1 Weather forecasts
      • 1.1.1 Sources of forecasts
      • 1.1.2 Understanding forecasts
    • 1.2 Wind
      • 1.2.1 Wind strength
      • 1.2.2 Effects of land on wind
      • 1.2.3 Sea and land breezes
      • 1.2.4 Anabatic and katabatic winds
      • 1.2.5 Wind, waves and tide
      • 1.2.6 Accounting for wind
    • 1.3 Other considerations
      • 1.3.1 Visibility
      • 1.3.2 Fog
      • 1.3.3 Thunderstorms
      • 1.3.4 River levels
    • 1.4 Synoptic charts
      • 1.4.1 Isobars and wind
      • 1.4.2 Low pressure
      • 1.4.3 High pressure
    • 1.5 Some meteorology
      • 1.5.1 Air masses
      • 1.5.2 Global circulation
      • 1.5.3 Depressions
      • 1.5.4 Depressions in practice
    • 1.6 Environmental clues
      • 1.6.1 Wind direction
      • 1.6.2 Clouds
    • 1.7 Maritime forecasts
    • 1.8 Weather and trip planning
      • 1.8.1 Deciding where, and if, to go
      • 1.8.2 Checking actual conditions
  • 2 Tides
    • 2.1 Introducing tides
      • 2.1.1 The moon
      • 2.1.2 The Sun - neaps and springs
      • 2.1.3 Meteorological effects
    • 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
      • 2.6.1 Races and overfalls
    • 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 Surf and Swell
    • 3.0.1 The life story of a wave
    • 3.0.2 Terminology
    • 3.1 Wind waves
      • 3.1.1 Wind forming waves
      • 3.1.2 Fetch
      • 3.1.3 Time to drop off
    • 3.2 Ground swell
      • 3.2.1 What is swell?
      • 3.2.2 Swell propagation
      • 3.2.3 Sets
    • 3.3 Waves and topography
      • 3.3.1 Waves in shallow water
      • 3.3.2 Refraction and focusing
      • 3.3.3 Diffraction
      • 3.3.4 Reflection
      • 3.3.5 Reefs and boomers
    • 3.4 Wind, waves and tidal streams
      • 3.4.1 Wind and waves against tide
    • 3.5 Surf
      • 3.5.1 Waves and beaches
      • 3.5.2 Surf height
      • 3.5.3 Surf zone features
    • 3.6 Swell and surf forecasts
  • 4 Navigation
    • 4.1 Maps and Charts
      • 4.1.1 Comparing maps and charts
      • 4.1.2 Which to use?
      • 4.1.3 Obtaining maps and charts
    • 4.2 Specifying position
    • 4.3 Latitude and longitude
    • 4.4 The units of the sea
      • 4.4.1 Distances and speeds
    • 4.5 The compass
    • 4.6 Reading charts
    • 4.7 Navigational marks
    • 4.8 Practicalities
      • 4.8.1 On the water
      • 4.8.2 On dry land
    • 4.9 Coastal pilotage
      • 4.9.1 Distance, speed and time
      • 4.9.2 Dead reckoning
      • 4.9.3 Compass use for coastal pilotage
    • 4.10 Signs of tidal flow
    • 4.11 Transits
    • 4.12 Fixes
    • 4.13 Low visibility navigation
      • 4.13.1 Short legs
      • 4.13.2 Aiming off
      • 4.13.3 Attack points
  • 5 Open water navigation
    • 5.1 Chartwork
      • 5.1.1 Measuring bearings
      • 5.1.2 Marking vectors
    • 5.2 Long crossings
      • 5.2.1 Option1: Multiple 1 hour vectors
      • 5.2.2 Option 2: Vectors over several hours
      • 5.2.3 Introduction to multiple hour vector method
    • 5.3 Choosing when to make the crossing
    • 5.4 Finding tidal stream data for long crossings
    • 5.5 Plotting tidal streams
    • 5.6 Finding the course to steer
    • 5.7 Determining estimated positions
    • 5.8 Navigating in open water
      • 5.8.1 Dead reckoning
      • 5.8.2 Fixes and cross bearings
      • 5.8.3 Distance off
      • 5.8.4 GPS

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. Resources used here include:

  • Very small extracts from OS maps, originally sourced through the Bing service before it was discontinued. Because Bing maps use a different projection to the Ordnance Survey, these maps will appear tilted from their normal orientation. In using these small extracts from a single OS map I rely on exceptions in UK copyright law for review and teaching.
  • 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.
  • 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!