Means ‘no’ or negative when made as a single-letter signal. Dash dot in Morse code, and November in phonetic.

A word deriving from the Latin navicella, a little boat, it is used for a small subsidiary hull, such as might be found in a trimaran, or for the pod which bulges beneath the bridge-deck in some catamarans to accommodate feet.

A boat has this sickness when her fastenings become loose. If you can identify those that leak, cut them out and replace by one size larger. Or you may clench up any that may be only slightly slack and insert new ones between every pair of old ones in suspect areas.

A narrow part of any channel, fairway or river

(or nautical calendar) A comprehensive book of tides, celestial phenomena and a thousand and one useful items of information for the navigator. No boat should go to sea without one.

The international nautical miles is 1852 metres. For practical pur­poses it can be called 6080 feet, or just over 2000 yards. A mile is divided into ten ‘cables’, each of which is therefore approximately 200 yards.

A metal deck fitting through which the anchor cable passes down to its locker.

Navigation Is the art of finding a ship’s position in the open sea, and of finding her way across the sea. Pilotage is the same thing in inshore waters where buoys and landmarks may be observed.

Official name for GPS.

A radio-printer service which enables a yacht to have an on-board print out of weather and navigational information, plus any other useful operational messages such as distress and rescue traffic

Or just ‘neaps’. These tides occur approximately every two weeks and have a smaller Range than Springs. See: ‘Tide’

Left high and dry, especially if the boat has gone aground on High tide at a time when the tidal range is decreasing, so that tomorrow’s High water will not be as high as today’s. In other words the tides are moving towards Neaps (or ‘Taking off’) and the boat will not float until neaps are over and Springs are approaching again.

A cape, promontory or low headland

A sharp bend in a rope, as when formed into an eye or when running round a sheave. (See Freshen.)

Electronic communication protocol universal to leisure boat instruments. Defined by the US National Marine Electronic Association.

Electronic communication protocol. Faster and more flexible than NMEA0183, NMEA2000 is becoming increasingy common and also forms the base of many proprietary systems. Defined by the US National Marine Electronic Association.

Divided into True or Magnetic North. The magnetic north pole is not at the same spot as the earth’s axial pole, and as charts are drawn with reference to True, while navigators use Magnetic compasses, a simple correction must be made. The correction differs as you move across the earth’s surface, and it is even very slightly different from one year to the next. Corrections are printed on admiralty charts.

A black cone, hoisted point up by Coastguards or other shoreside officials to indicate that a gale is expected from the North. By night three (red) lamps are hoisted in the form of a triangle, also point up. Note that the only choice is between ‘north’ and ‘south’. The South cone points downwards.

A chart or radar plot shown with north towards the top of the screen.

A vessel is in this condition when she cannot be controlled, perhaps by failure of her steering gear, even though her master is aboard and in charge. By night she carries two all-round red lights, one vertically above the other, instead of her forward and after white Steaming lights, but with her red and green Running lights and her Stern light if she is making way. By day she carries two Black balls or shapes, one vertically above the other.

Updates to published pilotage and chart information.

Pressure has been falling (rising) or steady in the preceding three hours, but at the time of observation was definitely rising (falling).

A buoy which is diamond-shaped when viewed from any side. It has a pointed top and a pointed bottom