Jacob's Ladder A rope ladder suspended from the side of a vessel used for boarding or leaving the vessel; e.g. as used by a pilot.

Jason Clause (Negligence General Average Clause)

A clause in ocean bills of lading providing that any general average will be borne proportionately by vessel, cargo, and freight even if the general average arises out of the vessel owner’s negligence, errors of the master or crew, or unseaworthiness of the vessel. Without this clause, cargo has no obligation to contribute to any general average arising from these causes.


Anything which is voluntarily cast overboard from a vessel in time of distress. See "Jettison" and "Flotsam."


The deliberate throwing overboard of cargo, or of part of the vessel's superstructure, equipment or stores, in the event of an emergency. Cargo or equipment might be jettisoned to lighten a vessel to relieve it from a strand, to stabilize it during a storm, or to get rid of flammables or explosives during a fire. (Washing overboard is the accidental loss of equipment or cargo overboard due to the action of the elements.)


A pier, mole, wharf, or other structure projecting into a body of water to influence the current or tide or to protect a harbor or shoreline.

Joint Policy - See "Subscription Policy."

Jones Act

A 1920 U.S. Statute which provides that a seaman injured by the negligence of the vessel owner, master, or fellow crew member can recover damages for his or her injuries from the vessel owner. See "Seaman’s Rights and Remedies."

Jury Rig

A temporary or makeshift arrangement of equipment set up to take the place of rigging or equipment which was lost or carried away; i.e. to make temporary repairs. Originally, in the days of sail, it referred to the ship’s masts and rigging. It now refers to any temporary repairs made to continue the operation of the equipment or vessel before a proper or complete repair can be made.

JWO (jettison and washing overboard) - See "Jettison" and "Deck Load Conditions."