Distance by Vertical Sextant Angle

Distance off a landmark of known height using the sextant vertical angle. Classical pilotage method.

Navigationpilotage

Landmark height above sea levelmMeasured sextant angle (corrected for dip)°Enter in decimal degrees (arcminutes/60 added).

Distance off: 173m

Distance off: 0.094nm

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 = \frac{h}{\tan(\theta)}

Symbol	Meaning	Unit
$h$	Landmark height above sea level	m
$θ$	Vertical sextant angle	°
$d$	Distance off	m (or nm)

Source: Admiralty Manual of Navigation BR45

In short

Distance off a landmark of known height using the sextant vertical angle.

Learn the theory Marine Voyage Planning and Routing