Oscar (phonetic)

As a single-letter signal, means ‘Man overboard’. It is three dashes in the Morse code, and Oscar in phonetic


Teased-out fibres of old hemp rope which are used for caulking seams before Paying.


Implement used for rowing – propelling a boat without the use of sails or engine. Usually used in pairs. The difference between an oar and a paddle is that the former is generally longer and that it is used in conjunction with a fulcrum such as a thole pin or a rowlock. The paddle is supported solely by the arms of the paddler. An oar has a Shaft, with a Blade at one end and a Loom at the other for the hands to grip.

Observed position

A more elegant term for a Fix, that’s to say a position deter­mined in relation to observable fixed objects or radio beacons, rather than the calculated position of dead reckoning.

Occulting light

A steady light with periods of darkness at regular intervals, but the general effect being more light that dark. A steady light with dark flashes, you might say. A Group Occulting light has two or more of these dark flashes at inter­vals, and is the dark complement to a Group Flashing light.

Off the wind

Downwind sailing. Sailing with the wind anything freer than a Reach.


That part of Inshore waters which is well clear of shoals and shore dangers, but still visible from the land.


Farther to seaward than Inshore. Not precisely defined, but the change from inshore to offshore would be understood to begin somewhere more than ten miles out, and roughly where the land disappears from sight. ‘Offshore’ is also sometimes used as an adjective, for example to describe a wind blowing seaward from the shore

Oil bag

A porous bag containing oil which is trailed astern so that the oil will gradually seep out and calm the sea. Detergent would probably do the job better, and would counter-balance the growing amount of unwanted oil that is polluting (but not calming) our seas …


Short for oilskins, a word still used to describe waterproof clothing, even when made of modern breathable materials

On the beam

Location description of an observed object to one side or the other. See also: Abeam.

On the bow

Said of something observed anywhere from dead ahead to forty-five degrees to port or starboard. More helpful if ‘port’ or ‘starboard’ is specified.

On the wind

Sailing Close-hauled or on a Fetch – with the wind coming from forward of Abeam.

One two three rule

See also: Rule of Twelfths


OOD stands for either: Officer of the Day or Offshore One Design.


A polyester resin that was widely used throughout hull laminates until the 1980s. Now often replaced by isophthalic in the outer layers.


A condition affecting glassfibre/FRP hulls that have absorbed water into the laminate to the extent that blistering can be seen in the gel coat.


See also: Stern drive.


Anything mounted or fitted beyond the normal area of the deck, or rail or bulwarks. A Bowsprit is ‘outboard’. So is an outboard motor, known for short as an ‘outboard’

Outfall buoy

A buoy marking the seaward end of a sewer pipe.


A rope used to pull something in an outward direction in relation to the centre of the boat. An outhaul pulls the tack of the jib to the bowsprit-end.


One of a variety of objects rigged outboard of the hull. In some rowing boats it is a bracket which carries the rowlock crutch outboard of the hull itself. In some sailing boats it is a subsidiary balancing hull set outboard of the principal hull by means of beams.


A turbulent area of the sea, with over-curling waves, usually caused by the Tidal stream running over a submarine ridge. The same thing is seen in shal­low and fast-running rivers. The chart may indicate ‘overfalls on the ebb’, say, or ‘overfalls with strong easterly winds’. Take note and keep clear – unless you ac­tually prefer rough water.


Overhanging ends – bow and stern – enabling an easier ride through waves. known as a Counter stern.

Overhaul, to

(1) Although you may ‘overhaul’ the engine of a boat just as you would an automobile, the word has a special use in connection with running rig­ging or block and tackle. It means to extend a tackle or sheet rather than to haul it in. Sometimes in light airs the main boom will not swing out because of the fric­tion in the blocks of the mainsheet. In that case you ‘overhaul’ the sheet to ease it out

(2) To overtake another boat, usually to windward.

Overtaking light

The same as the Stern light. Any vessel approaching in the arc through which this white light shines (67.5 degrees to port and starboard of dead astern) is an overtaking vessel in the meaning of the International Regulations, and must keep clear. The same arc holds force in daylight, of course.