Murmester key terms

The classification of a ship according to the trade or duty it performs, such as passenger, cargo, fishing, or tug, which determines the rules and certificates that apply to it.

A dimensionless measure of a ship's total enclosed volume under the tonnage convention, used for regulatory thresholds rather than for weight or cargo capacity.

A dimensionless measure of the earning capacity of a ship, derived from cargo and passenger spaces, used for fees, manning, and some regulatory limits.

The international treaty that sets the uniform method for measuring and certifying gross and net tonnage of ships engaged in international voyages.

The horizontal distance from the foremost to the aftermost point of the hull, excluding projections such as bowsprits, and used in berthing and regulatory length criteria.

The distance between the forward and aft perpendiculars, normally measured at the summer load waterline, used in structural, stability, and tonnage calculations.

The length used for load line and freeboard purposes, taken as a percentage of the waterline length at 85 percent of the least molded depth, subject to a minimum.

The vertical distance from the summer load waterline to the freeboard deck at side, representing the reserve buoyancy available above the water.

The circle and horizontal line on the shell plating amidships that fixes the position from which statutory freeboards are measured and verified at survey.

The document issued after survey confirming that a ship's load lines and freeboards comply with the applicable load line rules for its assigned conditions.

The watertight volume of the hull above the waterline that can be flooded before the ship sinks, giving it the ability to survive damage or added weight.

The ability of an undamaged ship to return to upright after being heeled, assessed through metacentric height, righting lever curves, and weather criteria.

The ability of a ship to remain afloat and upright after specified compartments are flooded, evaluated against required survival criteria for the vessel type.

The distance between the centre of gravity and the transverse metacentre, indicating initial stability; a small positive value means a stiff or tender ship.

The horizontal distance between the vertical lines through the centre of gravity and the centre of buoyancy at a given heel angle, producing the righting moment.

A private technical body that sets and verifies rules for hull, machinery, and equipment, issuing class certificates on which flag-state and insurer requirements often depend.

The government of the country whose flag a ship flies, responsible for applying international conventions and issuing or delegating the ship's statutory certificates.

The inspection by a coastal authority of foreign ships in its ports to verify compliance with international conventions, with powers to detain ships for serious deficiencies.

A certificate issued under a convention, such as safety construction or load line, confirming that the ship meets the standards required for its type and trade.

The international convention covering ship construction, fire safety, life-saving appliances, radio equipment, and navigation safety for ships on international voyages.

The international convention preventing pollution from ships, with annexes controlling oil, noxious liquids, sewage, garbage, and air emissions and setting survey requirements.

The international code requiring a documented safety management system ashore and aboard, with designated persons, procedures, and internal audits for ship operation.

A structured examination of a ship, its equipment, or its systems by a surveyor to confirm continued compliance, ranging from annual and intermediate to renewal surveys.

A formal order preventing a ship from sailing because deficiencies found at inspection pose a serious risk to safety, health, or the environment.

A transverse or longitudinal division capable of withstanding water pressure on one side, subdividing the hull to limit flooding and preserve stability after damage.

The foremost watertight transverse bulkhead, required at a set distance aft of the stem to limit flooding in a bow collision and protect the forward compartments.

A watertight space between the inner bottom and the outer hull, providing grounding protection, ballast capacity, and a barrier against bottom damage.

The machinery that drives the propeller or propulsion unit, typically a slow-speed two-stroke diesel, medium-speed diesel through gearing, or an electric motor.

A smaller engine driving generators, pumps, or compressors that support the ship's electrical load and services rather than the main propulsion function.

An independent power source, located outside the main machinery space, that supplies essential services such as steering, lighting, and radio after a blackout.

The electrical and mechanical functions that must remain available in an emergency, including steering gear, emergency lighting, alarms, and radio communication equipment.

The machinery that turns the rudder or steering nozzle, required to move the rudder from one side to the other within a specified time at full speed.

A permanently displayed drawing showing the location of fire divisions, detection and alarm devices, and firefighting equipment for use by the crew and shore firefighters.

A space bounded by fire-resisting divisions, usually by A-class bulkheads and decks, intended to contain a fire and limit its spread between areas of the ship.

A bulkhead or deck that resists fire and smoke for a stated period, typically 60 minutes, and is insulated to limit temperature rise on the unexposed side.

A permanently installed arrangement, such as CO2, foam, water spray, or inert gas, that discharges extinguishing medium into a protected space without manual handling.

Equipment such as lifeboats, liferafts, lifebuoys, and immersion suits provided for abandoning ship and surviving at sea, subject to approval and servicing rules.

A designated assembly point where passengers and crew gather during an emergency, marked and sized to hold the persons assigned to it safely.

A periodic exercise in which crew launch or simulate launching survival craft and practise emergency duties, recorded in the log and verified at survey.