Glossary Archive

The RYA Helmsman’s Practical course is designed to build confidence and competence in handling motorboats. Participants learn essential skills such as mooring, anchoring, and maneuvering in tight spaces. The course also covers basic engine checks, safety procedures, and collision regulations. Delivered in a hands-on format, this program is ideal for those new to motor cruising...

The radio frequency range between 3 and 30 megahertz (MHz), commonly used for long-range marine communications via skywave propagation.  High Frequency (HF) radio is an essential communication tool in the maritime industry, particularly for vessels operating beyond the range of Very High Frequency (VHF) and Ultra High Frequency (UHF) systems. HF radio waves can travel...

The highest level of sea water that can be predicted to occur under average meteorological conditions and under any combination of astronomical influences. The Highest Astronomical Tide (HAT) is a critical reference point in marine navigation and coastal planning. It represents the maximum tidal height that can be anticipated based solely on predictable astronomical factors,...

The radio frequency range between 3 and 30 megahertz (MHz), commonly used for long-range marine communications via skywave propagation.  High Frequency (HF) radio is an essential communication tool in the maritime industry, particularly for vessels operating beyond the range of Very High Frequency (VHF) and Ultra High Frequency (UHF) systems. HF radio waves can travel...

The UK government agency responsible for producing astronomical and navigational data for maritime and military use.  His Majesty's Nautical Almanac Office (HMNAO) is a division of the UK Hydrographic Office that provides essential astronomical and navigational information for seafarers, the military, and scientific institutions. Established in 1832, it produces publications such as the Nautical Almanac,...

A knot that attaches a rope to an object, such as a post, ring, or other rope. A hitch is a versatile and essential knot where securing a rope to an object is necessary. Unlike a bend, which joins two ropes, or a loop, which creates a fixed or adjustable loop in a rope, a...

This shape represents the Letter H (Flag Semaphore) and the Number 8 (Flag Semaphore).

International Morse Code sequence representing the letter H.

The organisation responsible for search and rescue operations in UK waters. His Majesty's Coastguard (HMCG) is a section of the MCA responsible for initiating and coordinating all maritime search and rescue within the UK Maritime Search and Rescue Region. This includes mobilising, organising and tasking adequate resources and assets, such as the RNLI or coastguard helicopters, to respond to persons in distress...

The UK government agency responsible for producing astronomical and navigational data for maritime and military use.  His Majesty's Nautical Almanac Office (HMNAO) is a division of the UK Hydrographic Office that provides essential astronomical and navigational information for seafarers, the military, and scientific institutions. Established in 1832, it produces publications such as the Nautical Almanac,...