Lubber line

Last updated

A lubber line, also known as a lubber's line, [1] [2] is a fixed line on a compass binnacle or radar plan position indicator display pointing towards the front of the ship or aircraft [3] and corresponding to the craft's centerline (being the customary direction of movement).

The line represents 0 degrees and is therefore the zero-point from which relative bearings are measured, e.g., "twenty degrees to port ".

Compasses on sailboats may have additional lubber lines at forty-five degrees from the centerline. This represents about as close to the wind as the average boat will sail. These lubber lines may be used when sailing close hauled to see if you are on the closest course to your destination, without having to add or subtract the 45 degrees every few minutes, or recalculate your required heading every time you tack. The main line on the compass reads your current (close-hauled) heading and the leeward lubber line will read the bearing to your destination, regardless of whether you are on port or starboard tack. Lubber lines also help you to see windshifts when racing. If you are sailing close-hauled with good trim and you notice that your bearing to the windward mark starts to drift outside the lubber line (angle becoming greater than 45 degrees) you are being headed, and should consider tacking.

Directional Gyros on aircraft also have additional forty-five degree lubber lines. These are useful for intercepting tracks and making procedure turns.

Etymology

The name comes from "lubber", a nautical term for a novice sailor or landlubber. It has also been called a lubber's mark or lubber's point, though use of these terms declined in the 20th century. [2]

Related Research Articles

Sailing Propulsion of a vehicle by wind power

Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water, on ice (iceboat) or on land over a chosen course, which is often part of a larger plan of navigation.

Compass Instrument used for navigation and orientation

A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers.

Sailing ship Large wind-powered water vessel

A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship, said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners. Still others employ a combination of square and fore-and-aft sails, including the barque, barquentine, and brigantine.

Bearing (angle) In navigation, horizontal angle between the direction of an object and another object

In navigation, bearing is the horizontal angle between the direction of an object and another object, or between it and that of true north.

Point of sail Direction of travel under sail relative to true wind direction over surface

A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface.

Jibe Basic sailing maneuver, where ship turns its stern through the wind

A jibe (US) or gybe (Britain) is a sailing maneuver whereby a sailing vessel reaching downwind turns its stern through the wind, which then exerts its force from the opposite side of the vessel. For square-rigged ships, this maneuver is called wearing ship.

Magnetic declination Angle on the horizontal plane between magnetic north and true north

Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north and true north. This angle varies depending on position on the Earth's surface and changes over time.

Air navigation Method used in air traffic control

The basic principles of air navigation are identical to general navigation, which includes the process of planning, recording, and controlling the movement of a craft from one place to another.

Automatic direction finder Marine or aircraft radio-navigation instrument

An automatic direction finder (ADF) is a marine or aircraft radio-navigation instrument that automatically and continuously displays the relative bearing from the ship or aircraft to a suitable radio station. ADF receivers are normally tuned to aviation or marine NDBs operating in the LW band between 190 – 535 kHz. Like RDF units, most ADF receivers can also receive medium wave (AM) broadcast stations, though as mentioned, these are less reliable for navigational purposes.

Piloting or pilotage is the process of navigating on water or in the air using fixed points of reference on the sea or on land, usually with reference to a nautical chart or aeronautical chart to obtain a fix of the position of the vessel or aircraft with respect to a desired course or location. Horizontal fixes of position from known reference points may be obtained by sight or by radar. Vertical position may be obtained by depth sounder to determine depth of the water body below a vessel or by altimeter to determine an aircraft's altitude, from which its distance above the ground can be deduced. Piloting a vessel is usually practiced close to shore or on inland waterways. Pilotage of an aircraft is practiced under visual meteorological conditions for flight.

This is a glossary of nautical terms; some remain current, while many date from the 17th to 19th centuries.

Tacking is a sailing maneuver by which a sailing vessel, whose desired course is into the wind, turns its bow toward and through the wind so that the direction from which the wind blows changes from one side of the boat to the other, allowing progress in the desired direction. The opposite maneuver to tacking is called 'jibe', or 'wearing' on square-rigged ships, that is, turning the stern through the wind. No sailing vessel can move directly upwind, though that may be the desired direction, making this an essential maneuver of a sailing ship. A series of tacking moves, in a zig-zag fashion, is called beating, and allows sailing in the desired direction.

Pelorus (instrument)

In marine navigation, a pelorus is a reference tool for maintaining bearing of a vessel at sea. It is a "simplified compass" without a directive element, suitably mounted and provided with vanes to permit observation of relative bearings.

Ship motions Terms connected to the 6 degrees of freedom of motion

Ship motions are defined by the six degrees of freedom that a ship, boat or any other craft can experience.

Junk rig Type of sail rig used in the Junk ships of dynastic China

The junk rig, also known as the Chinese lugsail or sampan rig, is a type of sail rig in which rigid members, called battens, span the full width of the sail and extend the sail forward of the mast.

Sailing into the wind is a sailing expression that refers to a sail boat's ability to move forward even if it is headed into the wind. A sailboat cannot make headway by sailing directly into the wind ; the point of sail into the wind is called "close hauled".

Hand compass Compact magnetic compass

A hand compass is a compact magnetic compass capable of one-hand use and fitted with a sighting device to record a precise bearing or azimuth to a given target or to determine a location. Hand or sighting compasses include instruments with simple notch-and-post alignment ("gunsights"), prismatic sights, direct or lensatic sights, and mirror/vee (reflected-image) sights. With the additional precision offered by the sighting arrangement, and depending upon construction, sighting compasses provide increased accuracy when measuring precise bearings to an objective.

SailTimer is a technology for sailboat navigation, which calculates optimal tacking angles, distances and times.

Rhumbline network Navigational aid drawn on early portolan charts

A rhumbline network, more properly called, a windrose network, or sometimes also called harbour-finding chart, compass chart, or rhumb chart, is a navigational aid drawn on early portolan charts dating from the medieval to early modern period. This network is like a web forming a grid on the map.

This is a list of nautical terms starting with the letters M to Z.

References

  1. "Navigation: The magnetic compass". www.britannica.com. Encyclopedia Britannica. Retrieved 15 June 2022.
  2. 1 2 "lubber". www.oed.com. Oxford English Dictionary. Retrieved 15 June 2022.
  3. Skill in the Surf: A Landing Boat Manual. U.S. Navy. 1945. p. 97. Retrieved 16 December 2018.