Glossary Archive

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.

A specialised agency of the United Nations headquartered in London and responsible for regulating shipping, the IMO has 175 Member States. The IMO is responsible for improving the safety and security of international shipping and preventing pollution from ships. It is also involved in legal matters, including liability and compensation issues and the facilitation of...

An impeller is a rotating component within a pump or compressor that is used to impart motion to a fluid. It typically consists of blades or vanes that are mounted on a central shaft and is designed to create flow and pressure within the fluid being pumped. In marine applications, impellers are commonly found in...

The RYA Improve Your Wingsurfing course is aimed at wingsurfers who want to refine their skills and gain more control. Participants learn advanced steering, upwind sailing, and techniques for handling stronger winds. The course also focuses on safety, efficiency, and optimizing equipment. By the end, wingsurfers will feel confident tackling a broader range of conditions...

Pronounced: IN-dee-ah The term for the letter I in the NATO Phonetic Alphabet.

A line or tackle used to pull a sail or spar inboard, typically to adjust sail shape or reduce projection beyond the hull. An in hauler is a control line or system used aboard sailing vessels to draw a sail, usually a headsail such as a jib or genoa, closer to the centreline of the...

A situation where a sailing vessel is stalled with its bow pointed directly into the wind, making it difficult to manoeuvre or gain forward momentum. When a sailing vessel is "in irons," it finds itself in a position where the bow is directly facing into the wind, and the sails are unable to catch any...

The RYA Inland Waterways Crew course provides essential training for assisting with operations on canals, rivers, and other inland waterways. Participants learn line handling, lock navigation, and basic safety procedures. The course emphasizes teamwork and practical skills needed to support the helmsperson effectively. By the end, participants will feel confident contributing as crew members on...