O
- Oakum
- Material used for caulking hulls. Often hemp picked from old untwisted ropes.
- Offing
- the more distant part of the sea as seen from the shore and generally beyond anchoring ground.
- Oiler (also replenishment oiler or fleet tanker)
- A naval auxiliary ship with fuel tanks and dry cargo holds designed to replenish other ships with fuel and supplies while underway on the high seas.
- Oilskins or oilies
- Foul-weather clothing worn by sailors.
- Old man, (The)
- Crew's slang for the captain (master or commanding officer) of a vessel.
- Old salt
- Slang for an experienced mariner.
- On station
- A ship's destination, typically an area to be patrolled or guarded.
- On the hard
- A boat that has been hauled and is now sitting on dry land.
- Ordinary
- See in ordinary.
- Oreboat
- Great Lakes term for a vessel primarily used in the transport of iron ore.
- Orlop deck
- The lowest deck of a ship of the line. The deck covering in the hold.
- Outboard motor
- A motor mounted externally on the transom of a small boat. The boat may be steered by twisting the whole motor, instead of or in addition to using a rudder.
- Outdrive
- The lower part of a sterndrive (qv).
- Outhaul
- A line used to control the shape of a sail.
- Outward bound
- To leave the safety of port, heading for the open ocean.
- Overbear
- To sail downwind directly at another ship, stealing the wind from its sails.
- Over-canvassed
- To have too great a sail area up to safely maneuver in the current wind conditions.
- Overfalls
- Dangerously steep and breaking seas due to opposing currents and wind in a shallow area, or strong currents over a shallow rocky bottom.
- Overhaul
- Hauling the buntline ropes over the sails to prevent them from chafing.
- Overhead
- The "ceiling," or, essentially, the bottom of the deck above you.
- Over-reaching
- When tacking, holding a course too long.
- Over the barrel
- Adult sailors were flogged on the back or shoulders while tied to a grating, but boys were beaten instead on the posterior (often bared), with a cane or cat, while bending, often tied down, over the barrel of a gun, known as #Kissing the gunner's daughter.
- Overwhelmed
- Capsized or foundered.
- Owner
- traditional Royal Navy term for the Captain, a survival from the days when privately owned ships were often hired for naval service.
- Ox-eye
- A cloud or other weather phenomenon that may be indicative of an upcoming storm.
Read more about this topic: Glossary Of Nautical Terms