Maritime glossary for AMSA oral exam study
Short, plain-language definitions of terms that come up when you study for an AMSA oral examination. Where a term has a full guide in the knowledge centre, the definition links to it. Definitions here are study aids written by Navisailor Learning Centre. For the exact wording of a convention, Act or marine order, use the current official text.
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Terms
- AMSA
- The Australian Maritime Safety Authority, Australia’s national maritime safety regulator. It issues seafarer certificates of competency and regulates domestic commercial vessels.
- Angle of loll
- The angle at which a ship with a negative metacentric height comes to rest, heeled to one side, because the righting lever becomes positive again at that angle. It is different from a list. Read the guide: Ship Stability Fundamentals: GM and GZ.
- Certificate of competency (CoC)
- A certificate showing that a seafarer has met the standard required to serve in a particular rank on a particular kind of vessel. AMSA issues them for Australia. Read the guide: Near Coastal Certificates Explained.
- Close-quarters situation
- A situation in which two vessels are so near each other that risk of collision exists unless prompt action is taken. Rule 19 of the COLREGs addresses it for restricted visibility. Read the guide: COLREGs: How to Reason Through a Situation.
- COLREGs
- The Convention on the International Regulations for Preventing Collisions at Sea. In Australia the regulations are given effect through Marine Order 30. Read the guide: COLREGs: How to Reason Through a Situation.
- Displacement
- The mass of water a floating ship displaces, which equals the mass of the ship and everything on board. It is the weight acting through the centre of gravity in stability calculations. Read the guide: Ship Stability Fundamentals: GM and GZ.
- Document of Compliance (DOC)
- A document issued to a company under the ISM Code after an audit confirms that its safety management system meets the Code. Read the guide: Safety Management Systems Explained.
- Domestic commercial vessel (DCV)
- A commercial vessel operating within Australian waters that is regulated under the Marine Safety (Domestic Commercial Vessel) National Law, with AMSA as the national regulator. Read the guide: Near Coastal Certificates Explained.
- ECDIS
- Electronic Chart Display and Information System: a navigation system that displays electronic charts with the ship’s position and can alert the watchkeeper to danger. Read the guide: Passage Planning in Four Stages.
- Free surface effect
- The loss of effective stability caused by liquid moving freely in a partly filled tank as the ship heels. It acts like a rise of the centre of gravity and depends strongly on the tank’s breadth. Read the guide: Ship Stability Fundamentals: GM and GZ.
- Give-way vessel
- The vessel that must keep out of the way of another under the steering and sailing rules, and must take early and substantial action to keep well clear. Read the guide: COLREGs: How to Reason Through a Situation.
- GM (metacentric height)
- The distance between a ship’s centre of gravity (G) and its transverse metacentre (M). A positive GM means the ship tends to return upright after a small heel. Read the guide: Ship Stability Fundamentals: GM and GZ.
- GZ (righting lever)
- The horizontal distance between the lines of action of a ship’s weight and buoyancy when heeled. It measures the moment that tries to return the ship upright. Read the guide: Ship Stability Fundamentals: GM and GZ.
- ISM Code
- The International Safety Management Code, made mandatory for most ships on international voyages through SOLAS Chapter IX. It requires a documented safety management system. Read the guide: Safety Management Systems Explained.
- KG
- The height of a ship’s centre of gravity above the keel. Loading weight high raises KG and reduces metacentric height. Read the guide: Ship Stability Fundamentals: GM and GZ.
- List
- A steady heel of a ship that has a positive metacentric height, caused by an uneven distribution of weight. It is corrected by moving or removing weight, unlike a loll. Read the guide: Ship Stability Fundamentals: GM and GZ.
- Marine order
- A legislative instrument made by AMSA under an Act, carrying many of Australia’s technical and operational maritime requirements. Orders are numbered and are amended from time to time. Read the guide: Australian Maritime Law and Marine Orders.
- MARPOL
- The International Convention for the Prevention of Pollution from Ships, which sets rules to prevent pollution of the marine environment by ships. Read the guide: Australian Maritime Law and Marine Orders.
- Near coastal
- The description AMSA uses for the domestic certificates of competency held by seafarers on domestic commercial vessels, each limited to the vessels and areas set for the certificate. Read the guide: Near Coastal Certificates Explained.
- Non-conformity
- In a safety management system, a situation where a procedure was not followed or a requirement was not met. The system should provide a way to report it and correct it. Read the guide: Safety Management Systems Explained.
- NSCV
- The National Standard for Commercial Vessels, a set of standards for domestic commercial vessels covering design, construction, equipment, crew and operation, published in parts. Read the guide: The NSCV Explained for Seafarers.
- OOW
- Officer of the Watch (more fully, officer in charge of a navigational watch): the officer responsible for the safe navigation of the ship while on watch. Read the guide: OOW Watchkeeper Oral Exam: Key Themes.
- Parallel indexing
- A radar technique in which a line fixed on the display shows how far the ship is from a chosen mark, so the watchkeeper can see at a glance whether the ship is staying on track. Read the guide: Passage Planning in Four Stages.
- Passage plan
- The berth-to-berth plan for a voyage, developed through appraisal and planning, then carried out and monitored by the bridge team. Read the guide: Passage Planning in Four Stages.
- Safety Management Certificate (SMC)
- A certificate issued to a ship under the ISM Code after an audit confirms that the company and shipboard management operate in line with the approved system. Read the guide: Safety Management Systems Explained.
- Safety management system (SMS)
- A documented system describing how a company or vessel operator manages safety: responsibilities, procedures, reporting, emergency preparation and review. Read the guide: Safety Management Systems Explained.
- SOLAS
- The International Convention for the Safety of Life at Sea, which sets minimum safety standards for the construction, equipment and operation of ships. Read the guide: Safety Management Systems Explained.
- Squat
- The increase in a moving ship’s draught, and the change in trim, caused by water flowing faster beneath the hull. It grows with speed and is greatest in shallow or confined water. Read the guide: Passage Planning in Four Stages.
- Stand-on vessel
- The vessel that keeps its course and speed when another vessel is required to keep out of its way, but must act if the give-way vessel does not. Read the guide: COLREGs: How to Reason Through a Situation.
- STCW
- The International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, which sets minimum standards of competence for seafarers. Read the guide: OOW Watchkeeper Oral Exam: Key Themes.
- Traffic separation scheme (TSS)
- A routeing measure that separates opposing streams of traffic into lanes, with Rule 10 of the COLREGs setting how vessels must behave in and near one. Read the guide: COLREGs: How to Reason Through a Situation.
- Under-keel clearance (UKC)
- The depth of water between a ship’s keel and the bottom. Planning allows for tide, squat, heel and wave motion and keeps a margin for uncertainty. Read the guide: Passage Planning in Four Stages.
- Vessel constrained by her draught
- A power-driven vessel that, because of her draught in relation to the available depth and width of navigable water, is severely restricted in her ability to deviate from her course. Read the guide: COLREGs Lights: A Recognition Method.
- Vessel not under command
- A vessel which, through some exceptional circumstance, is unable to manoeuvre as required by the COLREGs and is therefore unable to keep out of the way of another vessel. Read the guide: COLREGs Lights: A Recognition Method.
- Vessel restricted in her ability to manoeuvre
- A vessel which, because of the nature of her work, is restricted in her ability to manoeuvre as required by the COLREGs, such as one laying a cable or engaged in dredging. Read the guide: COLREGs Lights: A Recognition Method.