Sun Run Sun
Method: (An Example)
This is just a rough sketch as seen from a position plotting chart.
No scales are given.
1) Using the bearings of three of the stars observed, draw the bearing lines.
- Your estimated position will be the circle enclosed within the 3 lines
1) Plot your position using dead reckoning
- From a given position (the centre of the circle), the ship travels 20km/h for 2 hours at bearing 100o
- Hence a line of bearing of 100o, whose length is determined by the scale of the map is drawn.
(eg 4cm = 40km)
- At the end of 2 hours, the estimated position of the ship on the map is the end of the 4cm line and is called the dead reckoning point1 (DR1)
2) At the same time, plot the celestial position of the sun (CP1)
- this will give you your actual position on the map
(eg it is actually 1 km from the estimated position and slightly to the north)
3) Draw the bearing of the sun and form the position line (PL1)
4) From DR1, drop a perpendicular line to PL1
1) After another 2 hours, find your position using dead reckoning again.
- label the new point DR2
2) Find the celestial position of the sun at this time and draw the position line (PL2)
3) Transfer PL1 through DR2
- Something like drawing a line parallel to PL1 that passes through DR2
4) The point of intersection of PL1 and PL2 is observation point. This is where you are most likely to be found.
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