Conversion from 5 Nautical leagues to Feet

Information about the Nautical league (nlea)

The nautical league is a unit of length equal to three nautical miles, or exactly 5556 metres. It is longer than the land league by about 728 metres, since it is built from the nautical mile of 1852 metres rather than the statute mile.

The unit belonged to an era when it was the practical measure of coastal jurisdiction. The cannon shot rule, articulated in the seventeenth and eighteenth centuries, held that a state's authority extended as far as it could defend from shore, conventionally taken as three nautical miles. That distance became the standard territorial sea limit and was expressed as one marine league. Many older treaties and statutes define maritime boundaries in leagues for this reason.

The three-mile limit held for centuries before eroding through the twentieth. States progressively claimed wider waters, and the United Nations Convention on the Law of the Sea settled the matter in 1982 by establishing a twelve nautical mile territorial sea and a two hundred mile exclusive economic zone. Both figures are stated in nautical miles rather than leagues, and the older unit fell out of legal use.

Charts and pilot books from the age of sail used the league routinely for describing offshore distances and the visibility of landmarks. Reading those sources accurately requires knowing which league is meant, since the same word could refer to a land league, a marine league or a Spanish or Portuguese variant, and the differences are large enough to matter when reconstructing a historical position.

Today the unit has no navigational role. Charts are marked in nautical miles, and distances at sea are quoted the same way. The nautical league appears only in historical and legal texts.

The unit also underlies a familiar figure in visibility calculations. From a height of about three metres above sea level, the horizon lies roughly one nautical league away, which is why the three-mile limit corresponded loosely to what a lookout could see as well as to what a gun could reach.

One nautical league equals 3 nautical miles, 5556 metres, 5.556 kilometres, or about 3.452 statute miles.

Information about the Foot (ft)

The foot is a unit of length equal to exactly 0.3048 metres, or twelve inches. Its plural is feet and its symbol is ft, though a single prime is used in technical drawing and a straight apostrophe informally.

Units based on the human foot appear across the ancient world, and their lengths varied considerably. The Roman pes measured about 296 millimetres and was divided into twelve unciae, an arrangement English inherited directly. Medieval Europe supported dozens of local feet, and a merchant crossing a few borders might encounter several. The English foot was standardised in stages, but its exact modern value dates only from the International Yard and Pound Agreement of 1959.

Aviation is the foot's most significant surviving international domain. Aircraft altitude is reported in feet almost everywhere, and flight levels are expressed in hundreds of feet, so FL350 means 35,000 feet. Russia and China historically used metres, and China's transition to feet for most flight levels in 2011 removed a genuine safety hazard at the boundaries of adjoining airspace. Vertical separation standards are defined in feet, and reduced vertical separation minima allow 1000 feet between aircraft above 29,000 feet.

Construction in the United States works in feet and inches throughout, and lumber, ceiling heights and room dimensions all follow. Broadcasting and film retain the foot for lens focus scales and for measuring film stock. Water depth in diving is given in feet in American practice and metres elsewhere, a divergence that dive computers accommodate by offering both.

Twelve as a divisor is the foot's practical strength. It divides evenly by two, three, four and six, which suits carpentry and layout work where thirds and quarters are common. A decimal unit divides cleanly only by two and five.

Water and timber keep two of its derivatives alive. The fathom, six feet, measured the depth of water for as long as a sounding line was thrown by hand, and old charts are still marked in fathoms even where new ones use metres. The board foot, a volume of one foot square by one inch thick, remains the trading unit of sawn timber in North America, so a lumber yard quotes prices per thousand board feet. Both illustrate a general habit of the imperial system: rather than adding prefixes, it names each new quantity after the job it does, which makes the units memorable to those who use them and opaque to everyone else.

One foot equals 12 inches, 0.3048 metres, or 30.48 centimetres exactly.