ASA 105, Skill 11, Ded Reckoning (DR)
11. Plot a dead reckoning position on a chart using speed, time and course to steer. Deduced Reckoning or Ded Reckoning or DR ("dead" is a common misnomer) is based only on two factors: speed and direction. No outside influences are considered. For example: If you proceed due North at 6 knots in one hour your DR position is 6 nautical miles due North of the starting point. Use Chart 1210Tr for this exercise. Make a DR plot of three legs from Cleveland Ledge Light to Lone Rock at Quick's Hole, transit Quick's Hole, and finish at the entrance buoy for Menemsha Harbor, Bell "1." Assume a speed over ground of 6 knots. Mark of course Heading to next Distance to next Time to next R "14" Fl R 2.5 sec 215 deg T 12.2 nm 2 hrs 2 min BR Qk Fl G 167 deg T 2 nm 20 min G "1" Fl G 4 sec Bell 143 deg T 5.3 nm 53 min "1" Bell 19.5 nm 3h 15 m in transit Your DR plan looks something like this. Knowing one's departure time one can estim...