Jacob's Ladder
A rope ladder suspended from the side of a vessel and used for boarding.

Jettison
Act of throwing cargo or equipment (jetsam) overboard when a ship is in danger.

JIT
Abbreviation for "Just In Time." In this method of inventory control, warehousing is minimal or nonexistent; the container is the movable warehouse and must arrive "just in time;" not too early nor too late.

Joint Rate
A rate applicable from a point on one transportation line to a point on another line, made by agreement and published in a single tariff by all transportation lines over which the rate applies.