Unless otherwise noted, all entries are taken from A. G. Course. Dictionary of Nautical Terms (London: Arco Publications, 1962)

Able SeamanIn the Merchant Navy, he must serve three years on deck
at sea and be able to carry out the duties of a seaman. These include
steering, keeping a look out, rope splicing, painting overside, on deck and aloft, driving a winch or deck crane, rigging a derrick including work aloft, taking surroundings, working
in holds, securing hatchways, lowering lifeboats, etc. In sailing ship days, the brief term ‘hand, reef, and steer’ was used. In the Royal Navy, an Able Seaman must serve a specified period at sea as well as completing a course of instruction satisfactorily.
AftTowards, near, or at the stern of the ship; but always nearer to the stern of the ship from the position of a person using the word.
Allotment NoteAn authority given to a shipowner by a seaman, including an officer, to pay part of his wages to a near relative or a bank. At one time it was usually half pay, but more can now be authorised.
Allow and AloftAlow means low down and aloft up above. When used in conjunction, with regard to a square-rigged sailing ship, it means below and above the lower yards.
Anti-trade winds
Apprentice, sea
AsternThis refers to something, such as land or another ship, which is behind one’s own ship. The object is always outside the observer’s ship.
AwashThe decks of a ship are awash when seas break over the bulwarks on to them and the water washes from side to side. The word is also used with reference to rocks, shoals or wrecks when seas are washing over them and they become alternately wet and dry.
AweighThis is said of an anchor as soon as it has been hove clear of the bottom of the sea or river.
BallastWater carried in tanks or a heavy dry substance carried in lower holds and ‘tween decks of a ship when no cargo, or insufficient cargo, is obtainable to give her the necessary trim or stability.
Ballast LogsHeavy timbers lashed alongside sailing ships at water level to prevent them from capsizing after their cargo has been discharged. This was done in ports of the west coast of North America.
BarqueA sailing vessel with three, four or five masts which are square-rigged except on the after mast which has fore and aft sails. The names of the masts from forward to aft are: foremast, mainmast, mizzenmast, jiggermast, and driver (mast).
BowspritA spar or boom projecting out over the stem of a sailing ship at a slightly raised angle. Used for fitting fore and aft stays to the foremast.
JibboomThe boom projecting out beyond the bowsprit. It was introduced in the early eighteenth century.
Lay daysThe days kept aside in a ship’s voyage schedule for loading and unloading of the cargo. Lay days represent the time at which a ship must reach the charterer for cargo operations.
PilotA qualified person, with local knowledge, who assists the master to navigate his ship in and out of port. Although he usually takes charge of the ship the master is still responsible. Sea pilots and river pilots usually hold master mariners’ certificates. Dock pilots usually hold a local waterman’s licence.
Pilot CutterA small vessel, with accommodation for pilots, that cruises on the outside limits of a pilotage area to put pilots on board inward bound vessels and to take them off ships leaving the port.
Points of CompassThere are thirty-two, starting at north and working clock-wise right round and back to north. Each point consists of 11° 15′ and has a separate name. Courses were steered by points and half-points in sailing ships, but are steered by degrees in modern vessels.
SquallA sudden gust of wind and/or shower of rain. The wind in a squall may increase considerably and suddenly and may shift in direction. This had to be watched carefully in sailing ships, where it was often necessary to lower the yards and haul up the sails to prevent them from being blown away, or the ship from being heeled over dangerously on her side. Where black clouds (nimbus) reached down to the horizon, it was essential to note their direction and rate of progress. The usual practice in sailing ships was to stand by the halliards of the yards ready to lower away should the squall travel in the ship’s direction and show a likelihood of being dangerous. When the rain came before the wind the latter usually increased considerably.
Square-rigged shipApplied to a sailing ship with yards and square sails on her masts.
Studding Sail or StunsailAn extra sail set on each side of the square sails of a square-rigged ship. They were carried on booms fitted to the ends of the yards in fine weather. Tea and wool clippers had them in the second half of the nineteenth century, the last ship to carry them being the Hesperus in 1899.
TackingChanging the direction or course of a ship by turning her head into the wind, and continuing her swing, until the wind comes from the same number of points on the other bow. The alteration of course amounts to about 13 points in a square-rigged vessel. The wheel is put down and when the wind is from one to two points from right ahead the fore yards are hauled round to the other tack. When the wind is on the other bow the after and main yards are hauled round. In strong winds and gales wearing must be carried out instead of tacking because there would be too much weight on the fore side of the masts, when the sails were aback, for the fore and aft stays.
YardA wooden or steel cylindrical spar, with tapering ends, fitted horizontally across a mast. A square sail is secured to the head or top of the yard, which is named after the sail made fast to it, e.g., lower topsail yard.