DICTIONARY OF

Post Captain 260 Preventer Bolts
Post Captain. Former rank in R.N. Denoted a Captain who had been in command of H.M.
ship for three years.
Post Meridian. Post Meridiem.'
Post Meridiem. Latin for 'After noon'.
Post Ship. Former name for a first-class warship.
Pouch. Name formerly given to a 'grain feeder' or a space enclosed by shifting boards.
Pounding. The heavy falling of a ship into the sea, or on the ground, after having been lifted
by wave action.
Powder Magazine. Space in which gunpowder charges are stowed.
Powder Room. Space in which bulk gunpowder is stowed.
Prahu. Malayan craft propelled by oars and sails. About 50 ft. long. Also, double-ended
boat of Ladrone Islands. About 30 ft long and fitted with outrigger. Steered with paddle.
Pram. Dinghy built with a small tramson at the bow as well as at the stern.
Pratique. Permission for a vessel to traffic or have communication with the shore. Granted
after ship has been visited by medical and sanitary authorities.
Prayer Book. Seaman's nickname for a small holystone.
Precession. Movement of axis of a free gyro when subjected to an angular force that is not
coincident with plane of rotation. It results in direction and plane of spin taking up a position
so that each particle in gyro takes the shortest course to the new points arising from the
angular movement of axis.
Precession of Earth's Axis. Slow, circular movement of Earth's poles around axis of
Ecliptic at an angular distance of 23° 27'. Period of the movement is nearly 26,000 years.
Caused by gravitational pull of Sun and Moon and Earth's equatorial bulge.
Precession of Equinoxes. Gradual backward movement of First Points of Aries and Libra
along the Ecliptic so that their celestial longitudes are continuously decreasing.
Premium. Money paid for insurance against a marine risk.
Press Gang. Naval ratings, under an officer, who went ashore and impressed men into naval
service.
Press of Canvas. All sail set and all sails drawing.
Pressure Gradient. Rate of change of barometric pressure across isobars in a synoptic
chart.
Presumed Total Loss. Said of a vessel when she has not been sighted or heard of for a
considerable time but there is no evidence of her having sunk or being destroyed.
Preventer. Term applied to duplicated rigging. In some cases it seems to be used with its
original - and literal - meaning of 'coming before'.
Preventer Backstay. Topmast backstay that could be slacked off when on lee side and
vessel close-hauled.
Preventer Bolts. Through bolts along lower edge of preventer plate. Used for backing up
chain-bolts passing through upper edge of plate.