Recently I passed my RYA Day skipper theory and thought I would share my notes for my ChartWork

  • Tidal Stream Predictions = Tidal Stream Diamonds 
  • Measure boat Distance on Longitude ( Use side not the bottom)
  • To work out range of the tide Minus High Water( HW) from Low Water (LW) and use this to see if the tide Spring or Neaps
  • Tidal Stream Diamonds = Spring First Value , Neaps Second Value ( Degree = True ( T ) )
  • Tidal Stream Atlas is  Map of Direction of Tides  = Neaps First Value, Spring Second Value
  • Tidal Streams ( 04 = 0.4 )
  • Use plotter right way , make sure angle makes sense and is direction of travel
  • Windward is the Side of the boat the wind is coming from ( looard is opposite side )
  • Lattitude Measured in Degrees then Minutes ( 60′ in 1 °) then decimal (
  • True north ( T) is Direct via the Map, no Map Offset ( variation ) 120° (T) 
  • Magnetic is 120° (M)  measured on the Boat
  • True Measurment to Magnetic Measurement = West = + the Variation , East = – the Variation
  • Magnetic to true, add east or subtract west.
  • The true bearing of the transit is 068° (T) – 4° E = 064(M).
  • 1knot = Mile per hour
  • Round up SOG to nearest knot
  • GPS waypoint use BTW not COG for Bearing
  • Cable = 1/10 of a Nautical Mile
  • Example (T) true course is 014°, with leeway of  – 6° = 008°(T).variation is given as + 7° west which is added to give a course of 015° (M) Apply the deviation which would normally looked up in the deviation table, but in this case, is given as 4° east which is subtracted to give a course of 011°(C) compass.
  • Leeway would be 5° down wind so the ground track would be 275°(M). ( 270 Heading + 5 ) To counteract for the leeway and maintain the desired course over the ground, steer 5° towards the wind 265°(M). This would give a ground track of the desired 270°(M).
  • Waypoint = Way through not end
  • Plot Course Then Course to Steer = Tidal Move Point (c) + Knots with Cross of Plot Course
  • SOG ( Speed Over Ground ) = A – I

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