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Encyclopedia of Marine Technology


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Propeller, screw propeller

A revolving screw-like device that drives the ship. The screwtype propeller consists of a hub and blades, all spaced at equal angles about the axis. When the blades are integral with the hub, the propeller is known as a solid propeller.

Propulsion Condition Monitoring Service

In August 2010, Wärtsilä introduced its Propulsion Condition Monitoring Service (PCMS) for all types of propulsion machinery. This service aims to provide the customer with information about the condition of his propulsion equipment.

Propulsion shafting

A system of revolving rods that transmit power and motion from the main drive to the propeller. The shafting is supported by an appropriate number of bearings.

Propulsion system, propulsion plant

A system which provides thrust to propel the ship. It consists of propulsion machinery and the auxiliary systems needed to operate them...


Various devices used to propel ships: paddle wheels, screw propellers, thrusters, waterjets. For ocean-going ships various types of screw propellers have almost exclusive application.

Protection and Indemnity Clubs (P&I Clubs)

The Clubs are associations of shipowners and charterers, owned and controlled by the insured shipowner or charterer “Members”.


Flag state protection of own shipping by the elimination of certain competive elements.

Provision stores

Refrigerated stores intended to preserve perishable foods for shipboard use.

Public address system

Loudspeakers in cabins, mess rooms, etc., and on deck via which important information can be broadcast from a central point, mostly from the navigation bridge.

Public spaces

Those portions of the accommodation which are used for halls, dining rooms, lounges and similar permanently enclosed spaces, (SOLAS).


A machine used to raise liquids from a low level to a higher one, or to provide liquid with an increase in energy enabling it to flow or build up a pressure.

Pump room

A space, located in the cargo area, containing pumps and their accessories for the handling of ballast and fuel oil.


The unlicensed member of the engine department. He is trained in all skills necessary to engine maintenance. Usually watchstander, but on some ships a day worker.

Pure car, truck carrier (PCTC)

The PCTC is a purpose-built vessel for the transportation of different types of rolling cargo, such as new private cars and trucks, heavy construction equipment, and other heavy loads.

PureVent system

Alfa Laval’s compact air separator designed to remove oil mist from crankcase gases with a cleaning efficiency of 99%.

Purging of cargo tanks with inert gas

The introduction of inert gas into a tank already in the inert condition, with the purpose of further reducing the existing oxygen content...


Separation of two intermixed and mutually insoluble liquid phases of different densities. Solids having a higher density than the liquids can be removed at the same time.


A separator that cleans the oil from water and solid particles with continuous removal of separated water.

Purse seiner

A fishing vessel catching pelagic species by surrounding the shoals with purse seines.

Purse seiner/trawler LIBAS

Norwegian shipyard Fitjar Mek Verksted AS completed the 94m fishing vessel LIBAS according to the design from Vik-Sandvik AS, who developed a new hull form for a speed of 20 knots in loaded conditions.

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