Nautical Dictionary
Nautical Glossary - Maritime Terminology
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
- Oakum
- A material made of tarred hemp or manila rope fibers, used for caulking seams of decks and sides of a wooden ship in order to make them watertight.
- Oar
- A pole with a blade at the end used to row a rowboat. Oars are different than paddles because they have a provision to be secured to the rowboat for rowing, such as an oarlock. The three parts to an oar are: the blade, the part which enters the water; the shaft, the main body of the oar: and the loom, the inboard end on which the rower pulls.
- Oarlock
- A device to attach oars to a rowboat, allowing the operator to row rather than paddle the boat.
- Observed Position
- A position or fix determined by observing landmarks or other objects to find the position.
- Occulting Lights
- A navigational light which turns on and off in a regular pattern, but is on more than it is off, so the period of light is longer than the period of darkness.
- Off and Fair
- Order to take off a damaged part of a vessel, to restore it to its proper shape and condition, and to replace it in position.
- Off Soundings
- In blue water beyond the 100-fathom line.
- Off the Wind
- Sailing with the wind coming from the stern or quarter of the boat.
- Officer
- Any of the licensed members of the ship's complement.
- Officer's Mess
- Dining room facilities for officers separate from the crew and passenger dining room.
- Official Number
- Definition and cross-reference to Tonnage.
- Offing
- Seaward, a safe distance from shore; To keep an offing is to keep a safe distance away from the coast because of navigational dangers, fog, or other hazards.
- Offshore
- Away from land, toward the water.
- Offshore Wind
- Wind blowing from off the shore.
- Offwind
- Any point of sailing away from the wind.
- Oil Bag
- Used in emergencies, this is a container which allows oil to drip into the sea in heavy weather. An oil slick is produced which prevents waves from breaking over the deck of a boat.
- Oiler
- A member of a ship's engineering crew who assisted the chief engineer with lubricating and maintaining the engine.
- Old Salt
- A very experienced and/or old sailor
- On a Tack
- A sailboat is always on one tack or the other; that is the sail is always on one side or the other.
- On Board
- On or in a ship.
- On the Beach
- Said of a seaman who has retired from sea service.
- On the Beam
- The direction at right angles to a ship's heading or the line of her keel
- On the Bow
- To the bow of the boat, forward of the beam.
- On the Hard / On the Ways
- Hauled out of the water for repairs or storage
- On the Quarter
- A direction of forty-five degrees or less from the stern.
- On the Wind
- Sailing close hauled. Sailing toward the wind as much as possible with the wind coming from the bow.
- One o'clock gun
- In Edinburgh, Scotland, cannon fired from the Royal Castle in order that the fleet's clocks could be synchronized. Now, a remark to become timely.
- 1 One-design
- Any boat built to certain standards or rules so that is like all others in the same class.
- Onshore
- Toward the shore
- OOD
- Navy term meaning Officer of the deck.
- Open
- A location that is not sheltered from the wind and seas. An open location would not make a good anchorage.
- Ordinary Seaman (OS)
- An apprentice Able Seaman, assists AB's, bosun, and officers, keeps facilities clean.
- Orlop
- Name given to the lowest deck in a ship.
- Out of Trim
- Sails that are not properly arranged for the point of sail that the boat is on. The sails may be luffing or have improper sail shape, or the boat may be heeling too much. These conditions will slow the boat down.
- Out Point
- To sail closer to the wind than another boat on the same tack.
- Outboard
- (1) Toward or beyond the boat's sides. (2) A detachable engine mounted on a boat's stern.
- Outdrive
- A propulsion system for boats with an inboard engine operating an exterior drive, with drive shaft, gears, and propeller; also called stern-drive and inboard/outboard.
- Outer Skin
- The outside plating of a vessel.
- Outhaul
- A control line that adjusts tension along the foot of the sail, pulling the clew away from the tack; used to maintain proper sail shape.
- Outrigger
- A structure which extends outboard beyond the edge of the hull for some special purpose. Some Polynesian canoes use outriggers to support an "ama" or small secondary hull, while fishing boats may use outriggers to suspend lines or nets over the water.
- Overboard
- In the water outside of the vessel.
- Overfall
- Dangerously steep and breaking seas due to opposing currents and wind in a shallow area.
- Overhang
- The area of the bow or stern projecting above and beyond a perpendicular from the water line at stem or stern.
- Overhaul
- (1) Repairing or refitting. (2) To overtake another ship at sea. (3) To extend a tackle so that distance between blocks is increased.
- Overhead
- Nautical equivalent of ceiling
- Overlap
- The distance the bow of a boat is forward of another's stern
- Overstand
- Sailing beyond a racing mark or buoy whereby you sail a greater distance
- Overtaking
- Passing another vessel.
- Owner's Flag
- A boat owner's private pennant.