J

A device for lifting heavy loads a short distance, such as a hydraulic or screw jack; also a small national flag flown at the bow.

A mobile offshore platform with legs that are lowered to the seabed to raise the hull clear of the water for drilling or other work; see jack-up drill rigs.

Mobile offshore units that float to location and then jack their hull up legs resting on the seabed, providing a stable platform for drilling in shallow water.

The closed fresh-water circuit that cools an engine's cylinder jackets, carrying away combustion heat, itself cooled by seawater or a central cooler.

A louvred opening or shutter that admits air while excluding rain and direct view.

The deliberate throwing overboard of cargo to lighten or save a ship in peril, which may give rise to a general-average claim.

A structure built out from the shore at which ships berth to load and discharge.

The layout and fitting-out of accommodation, including partitions, linings, doors, and fittings supplied by joiner work.

The change in temperature of a gas as it expands through a restriction without doing external work, exploited in the cooling and liquefaction of gases.