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Encyclopedia of Marine Technology


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Steps used aboard ship in place of stairs. The angle of inclination for a vertical ladder should be between 75–90 degrees. Continuous ladders should not exceed 9.1m (30 ft) in height.


An insulating material applied to surfaces of pipes, or the boiler casing in order to reduce heat transfer.

Laid-up tonnage

Ships not in active service; a ship which is out of commission for fitting out, awaiting better markets, needing work for classification, etc.


A type of ship which trades only in the Great Lakes of North America. They usually carry grain and ore cargoes.

Laminar flow

A fluid flow in which the adjacent layers do not mix.


An excessively large, laminar, non-metallic inclusion, producing a defect appearing in sheets or strips as segregation or in layers. Severe lamination can be repaired by a local insert plate.


Prominent objects on land (churches, towers, high buildings, etc.), beacons and lighthouses serving as guides to steer by, when approaching an estuary, river or harbour.

Lap joint

A joint between two overlapping members in parallel plane.

LASH (Lighter aboard ship)

A barge carrier designed to act as a shuttle between ports, taking and discharging barges (lighters). The ship is provided with massive crane which loads and discharges the lighters over the stern.


Wires, chains, ropes, or straps used to secure cargo on a ship. See also container lashing equipment.

Lashing bridge

A strong steel structure installed between hatches to permit the stowage of an additional tier of containers or heavier containers in the upper tier. Lashings can be applied at a higher level but can also remain short.

Latent heat

The heat energy required to bring about a change of state of a unit mass of a substance, without any change in temperature, e.g. from solid to a liquid.


A resin used in emulsion paints.


A motorboat intended for operation in ports, bays and on calm water, limited to a wind force not exceeding 4 Beaufort scale. Seagoing launches are units intended for seagoing service, limited to a wind force not exceeding 6 Beaufort scale.

Launch and recovery system of the underwater unit

The lifting equipment necessary for raising, lowering and transporting the underwater unit between the surface and the working site.


The transfer of a ship from land to water. The traditional launching is the sliding of a ship by its own weight into the water down inclined launch ways.

Launching appliance or arrangement

A means for transferring a survival craft or rescue boat from its stowed position safely to the water.

Launching ramp angle

The angle between the horizontal and the launch rail of the lifeboat in its launching position with the ship on even keel.

Launching ramp length

The distance between the stern of the lifeboat and the lower end of the launching ramp.


The arrangement of plant and equipment in, for example, a machinery space, or a drawing thereof.

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