Glossary Archive

A lifting surface or structure mounted beneath a vessel's hull that, when moving through water, generates lift to raise the hull above the waterline, reducing drag and increasing speed. A hydrofoil is a specialised marine technology designed to improve the efficiency and performance of watercraft. The hydrofoil itself is a wing-like structure, often made of...

The science of surveying the waters of the earth and adjacent land area, and publishing the results in charts, pilots, etc, for example Admiralty charts

The International Association of Lighthouse Authorities (IALA) is an international organisation that aims to promote safe, efficient, and sustainable navigation by coordinating the efforts of national and regional lighthouse authorities worldwide. IALA develops and maintains standards and guidelines for maritime navigation aids, such as lighthouses, buoys, and beacons, to ensure consistency and interoperability across different...

An official document that certifies a person's ability to operate a pleasure craft in countries that recognise it.  The International Certificate of Competence (ICC) is a standardised qualification that demonstrates a boater's competency to operate a pleasure craft in international waters where it is recognised. It is issued by authorised national authorities and is often...

The International Maritime Signal Flag India. Meaning I am altering course to port.

A system of flags, codes, and symbols used by ships to communicate essential messages and ensure safety at sea, regardless of language barriers. The International Code of Signals (ICS) is a globally recognised communication system designed to facilitate clear and unambiguous exchanges between vessels and between ships and shore stations. Established in the early 19th...

An imaginary longitudinal line located at approximately 180 degrees longitude serving as the demarcation where the calendar date changes by one day when crossed. The International Date Line (IDL) is a conceptual boundary on the Earth's surface, primarily situated along the 180th meridian in the mid-Pacific Ocean. It is not a straight line but zigzags...

An intergovernmental organisation dedicated to ensuring the uniformity and standardisation of hydrographic and nautical charting practices globally to support safe navigation and the sustainable use of marine environments. The International Hydrographic Organization (IHO), established in 1921 and headquartered in Monaco, is the principal authority for coordinating global hydrographic efforts. Its primary aim is to ensure...

This shape represents the Letter I (Flag Semaphore) and the Number 9 (Flag Semaphore).

International Morse Code sequence representing the letter I.