Compass (C)
+/- Deviation (is specific to the boat and the course it is sailing on)
= Magnetic (M)
+/- Variation (the effect of deviation is the same for all boats in the same area at the same time)
= True (T)
+/- Leeway
= Water Track (WT, >)
Tidal Streams (>>>)
= Ground Track (Course over Ground, COG, >>)
Rule: C ADE T (Compass to true add east)
Dead Reckoning (DR)
It’s possible to reckon your approximate position if you know:
– the course streered (T)
– the distance travelled (measured by log)
Estimated Position (EP)
An EP allows for the effects of leeway and tide and should therefore be more accurate than a DR position.
