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