JACK LINE - A strong line, or a wire stay running fore and aft along the sides of a boat to which a safety harness can be attached.
JACK NASTYFACE - Nickname for an unpopular seaman. Originally, nom de plume of a seaman who wrote a pamphlet about conditions in Royal Navy in early years of 19th century.
JACOBS LADDER - A rope ladder, lowered from the deck, as when pilots or passengers come aboard.
JERQUE - Search of a vessel, by Customs authorities, for un-entered goods.
JETSAM - Goods that have been cast out of a ship and have sunk
JETTISON - To throw overboard.
JETTY - A structure, usually masonry, projecting out from the shore; a jetty may protect a harbor entrance.
JIB – A triangular foresail in front of the foremast.
JIB SHEET - The lines that lead from the clew of the jib.
JIBBOOM - Spar forward of bowsprit
JIBE (GYBE) - To go from one tack to the other when running with the wind coming over the stern
JIFFY REEFING - Reducing sail by lowering and securing with lines.
JIGGER - Aft sail on the mizzen mast of a yawl or a ketch. After mast (4th mast) on schooner or sailing ship carrying a spanker.
JIMMY BUNGS - Nickname for a ship's cooper.
JIMMY THE ONE - First lieutenant or executive officer
JONES, JOHN PAUL S - (Scot.-born) naval officer & hero in American Revolution; as captain of ship
- Native sailing vessel common to the Far East Seas
JURY RIG –
A makeshift rig