Dead-Reckoning Position

Advance an initial position by a course and speed for a given elapsed time - the basic DR calculation.

NavigationDR

Start latitude°Start longitude°True course°TSpeed over groundknElapsed timemin

Distance travelled: 12.00nm

New latitude: 51.5000°

New longitude: 0.3213°

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

d\text{Lat} = D \cdot \cos C, \quad \text{Dep} = D \cdot \sin C, \quad d\text{Lon} = \tfrac{\text{Dep}}{\cos L_m}

Symbol	Meaning	Unit
$C$	True course	°T
$D$	Distance	nm
$L_m$	Mid-latitude	°
$Dep$	Departure (east-west distance in nm)	nm

Source: Bowditch - American Practical Navigator

In short

Advance an initial position by a course and speed for a given elapsed time - the basic DR calculation.

Learn the theory Marine Voyage Planning and Routing