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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 What causes the tides?
      • 2.1.1 The moon
      • 2.1.2 The Sun - neaps and springs
      • 2.1.3 Meteorological effects
    • 2.2 Tide tables
      • 2.2.1 Tidal range
      • 2.2.2 Tidal factor*
    • 2.3 Tidal streams
      • 2.3.1 Tidal diamonds
      • 2.3.2 Tidal stream atlases
      • 2.3.3 Pilots and guidebooks
    • 2.4 Paddling with tidal flow: Predicting speeds of tidal streams
      • 2.4.1 Changes between neaps and springs*
      • 2.4.2 Variation of flow through the tidal cycle*
      • 2.4.3 50/90 rule*
      • 2.4.4 Rule of thirds
    • 2.5 Depth of tide
      • 2.5.1 Predicting high and low water*
      • 2.5.2 Determining heights of high and low water*
      • 2.5.3 Estimating the depth of the tide
    • 2.6 Environmental considerations
      • 2.6.1 Behavior of tidal streams
      • 2.6.2 Races and overfalls
      • 2.6.3 Signs of tidal flow
  • 3 Surf and Swell
    • 3.1 Introduction to surf and swell
      • 3.1.1 The life story of a wave
      • 3.1.2 Terminology*
    • 3.2 Wind waves
      • 3.2.1 Wind forming waves
      • 3.2.2 Fetch
      • 3.2.3 Time to drop off*
      • 3.2.4 Uncomfortable sea states
    • 3.3 Ground swell
      • 3.3.1 What is swell?
      • 3.3.2 How does swell work?*
      • 3.3.3 Swell propagation*
      • 3.3.4 Sets*
    • 3.4 Waves and topography*
      • 3.4.1 Waves in shallow water
      • 3.4.2 Refraction and focusing
      • 3.4.3 Diffraction
      • 3.4.4 Reflection
      • 3.4.5 Reefs and boomers
    • 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
    • 3.7 Environmental considerations
      • 3.7.1 Reefs and gravel bars
      • 3.7.2 Rouge waves
      • 3.7.3 Dumping surf
    • 3.8 Wind, waves and tidal streams
      • 3.8.1 Wind and waves against tide
      • 3.8.2 Tide races / overfalls
      • 3.8.3 Wind / waves with the tide*
  • 4 Navigation
    • 4.1 Practicalities*
      • 4.1.1 On the water
      • 4.1.2 On dry land
    • 4.2 Maps and Charts
      • 4.2.1 Comparing maps and charts
      • 4.2.2 Reading charts*
      • 4.2.3 Which to use?
      • 4.2.4 Obtaining maps and charts
      • 4.2.5 Other sources of maps
    • 4.3 Coastal pilotage - handrailing
      • 4.3.1 Compass use for coastal pilotage*
    • 4.4 Distance, speed and time
      • 4.4.1 The units of the sea*
      • 4.4.2 Distance, speed and time calculations
      • 4.4.3 Dead reckoning*
    • 4.5 Navigation tricks
      • 4.5.1 Short legs
      • 4.5.2 Aiming off
      • 4.5.3 Attack points
    • 4.6 The compass and bearings
    • 4.7 Specifying position
      • 4.7.1 Grid references
      • 4.7.2 Latitude and longitude*
    • 4.8 Navigational marks*
    • 4.9 Formal navigation for short crossings
  • 5 Open water navigation
    • 5.1 General techniques for tidal and non-tidal waters
      • 5.1.1 Dead reckoning
      • 5.1.2 Transits
      • 5.1.3 Following a bearing
      • 5.1.4 Fixes*
      • 5.1.5 Distance off*
      • 5.1.6 GPS
      • 5.1.7 Responsibilities for navigating
    • 5.2 Open Water Navigation in tidal waters
      • 5.2.1 Chartwork
      • 5.2.2 Long crossings
      • 5.2.3 Choosing when to make the crossing
      • 5.2.4 Finding tidal stream data for long crossings
      • 5.2.5 Plotting tidal streams
      • 5.2.6 Finding the course to steer
      • 5.2.7 Determining estimated positions
    • 5.3 Risks and challenges of open crossings

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!