NAVIGATION
Distance at Sea — calculations
THE CURVATURE OF THE EARTH
Distance to Horizon (miles)
= 1.22459 x √Height above Sea Level (feet)
On the Beach (at 5.5 feet high)
On the Beach (at 5.5 feet high)
= 1.22459 x √5.5
= 2.872 miles
= 2.496 nautical miles
= 4.622 km
= 5055 yards
On the Quarter Deck (at 25 feet high)
On the Quarter Deck (at 25 feet high)
= 1.22459 x √25.0
= 6.123 miles
= 5.321 nautical miles
= 9.854 km
= 10776 yards
In the Masthead (at 120 feet high)
In the Masthead (at 120 feet high)
= 1.22459 x √120.0
= 13.415 miles
= 11.657 nautical miles
= 21.589 km
= 23610 yards
In the Nest (at 190 feet high)
In the Nest (at 190 feet high)
= 1.22459 x √190.0
= 16.880 miles
= 14.668 nautical miles
= 27.165 km
= 29708 yards
In the Lighthouse (at 513 feet high)
In the Lighthouse (at 513 feet high)
= 1.22459 x √513.0
= 27.736 miles
= 24.102 nautical miles
= 44.637 km
= 48815 yards
Notes
-
√ = square root
-
Height above sea level at eye level
-
Rounded to three decimal points
DID YOU KNOW...?
One nautical mile is equal to one minute of latitude.
A Note...
Aspects of navigation are an integral part of any ship in the age of sail. The hardships of such often mentioned the naval adventure fiction series "Ships of War" by Bradley John. From time to time, you too will be confronted (perhaps even confounded) by the nautical calculations suddenly presented, often in need to save the ship and their lives. Naturally, they were not afforded the ease of modern technologies such as GPS, computers or even rudimentary calculators.
