Posts Tagged ‘navigation’

PostHeaderIcon DMG

three letter initialism for Distance Made Good. The distance between starting and ending reference points, as measured along either a rhumb line or great circle route connecting the two points. Compare to: CMG and SMG.

PostHeaderIcon Emergency Tiller

a temporary bar or arm fitted to the head of a boat’s rudder. The emergency tiller is used to directly operate the rudder when wheel steering fails.

PostHeaderIcon Bight

1) An open loop in a line. “The bight” is the potentially dangerous area within a bight of line that is under load. For example, anyone sitting inside the bight of a working spinnaker sheet run through a turning block would likely be severely injured by both the sheet and shrapnel if the block’s sheave separated from its frame. 2) a shallow ocean inlet or indentation along a shoreline, such as the sea area between two promontories. Compare to: headland.

PostHeaderIcon Shoal

a shallow area typically composed of sand, silt or rocks, within or that projects beyond the coastline of a body of water. A shoal may become exposed at low tide and always poses a danger to boats. See also: shoal draft keel.

PostHeaderIcon Aids-to-navigation

any devices external to a boat specifically intended to assist in determining a position or safe course, or to warn of danger or obstructions. These include buoys, day beacons, lighthouses, markers, radio beacons, and range lights. Aids-to-navigation are typically shown on nautical charts. Electronic devices used for navigation are also called aids-to-navigation. Alternative terms include ATON and navaid.

PostHeaderIcon Fat Layline

your sailing line to a mark along which you will have to foot or reach in order to round close to the mark. Your sailing line to a mark when you have over-stood it. Compare to: thin layline.

PostHeaderIcon North Pacific High

a semi-permanent center of high atmospheric pressure located over the North Pacific Ocean between 30 and 40 degrees North latitude and between 140 and 150 degrees West longitude. The North Pacific High has a major influence on boats competing in any of the trans-pacific races, including Transpac, Pacific Cup and Vic-Maui. See also: slot cars.

PostHeaderIcon Reaching

sailing with the true wind coming from between 45 and 150 degrees off the bow. If a boat is heading towards 12:00 and the winds are from 1:30 to 2:45 or 9:15 to 10:30, the boat is on a close reach. If the winds are from approximately 3:00 or 9:00, the boat is on a beam reach. A boat is broad reaching when the wind is from 3:15 to 5:00 or 7:00 to 8:45. Higher than close reaching is close-hauled. Lower than broad reaching is a run. See also: beam reach, broad reach, close-hauled, and power reaching.

PostHeaderIcon Equator

an imaginary line around the Earth equidistant from the poles and that divides the Earth into Northern and Southern hemispheres. The equator is the 0-degree parallel of latitude and the longest parallel of latitude as it lies along the largest east-west circumference of the Earth. Compare to: Prime Meridian.


PostHeaderIcon Potato Patch

the Potato Patch shoal on the North side of the entrance to San Francisco Bay; part of the Four Fathom Bank. So named because, back in the 1800s, boats carrying potatoes from farms around Bolinas Lagoon to markets in San Francisco would occasionally run aground on this sand bar and spill their cargo. Compare to: Onion Patch.


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