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Sailing reference
Clear explanations of the language used in navigation, pilotage, weather, safety and life under sail.
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The mileage counter used to measure how far you have sailed
The distance run comes from the ship's log, a paddlewheel, impeller or electromagnetic sensor measuring speed through the water and integrating it to a totalising distance. Log readings should be recorded at every fix, course change and watch change so any interval can be reconstructed. Impeller logs foul quickly with weed and growth and under-read progressively, so the log should be calibrated against a measured distance run in both directions to cancel tidal effect.
Read definition →Light with a single flash lasting two seconds or more
A long flash is defined as a flash of not less than two seconds duration. LFl 10s, one long white flash every ten seconds, is the classic landfall and safe water buoy rhythm, chosen because a long flash is easier to pick up at extreme range and against a lit shoreline than a short one. The long flash is also the terminal element in the south cardinal rhythms Q(6)+LFl 15s and VQ(6)+LFl 10s.
Read definition →Mandatory reporting scheme where ships send position to flag authorities
Established under SOLAS Chapter V Regulation 19-1 and applying to passenger ships, cargo ships of 300 gross tonnage and upwards on international voyages and mobile offshore drilling units. Equipment transmits identity, position and time normally four times a day via satellite communications to a data centre. Unlike AIS the reports are not broadcast openly, access being restricted to flag, port and coastal states within defined distances, which makes LRIT a security and SAR tool rather than a collision avoidance aid.
Sailing reference
Clear explanations of the language used in navigation, pilotage, weather, safety and life under sail.