Glossary Archive

Heaving To is a sailing maneuver used to stop or significantly slow down a sailing vessel by positioning the sails and rudder in a specific way. It’s commonly used in rough weather when the crew needs a break or for repairs. The boat remains relatively stable, drifting slowly but not progressing much forward. How it...

Sea area of the Met Office Shipping Forecast. Covers waters around the Hebridean islands off western Scotland. Covering the Hebridean archipelago, Hebrides sees frequent westerly gales of Force 8–9 and turbulent seas amplified by island up-draughts. It hosts Europe’s largest puffin colony and winter winds often reach Force 10.

Tilt or lean to one side, typically due to wind pressure on a sailing vessel's sails. The term "heel" is widely used in recreational and professional marine contexts to describe the lateral tilt or inclination of a vessel. This phenomenon is most commonly associated with sailing yachts, where the force of the wind acting on...

The vertical distance from the water's surface at Mean High Water Springs to the focal plane of a lighthouse's light source. Height of Light is a useful measurement in maritime navigation, as it determines the distance at which a lighthouse's light can be seen by vessels at sea. This measurement is taken from Mean High...

The vertical distance between the water's surface at any given time and the established chart datum, typically the lowest astronomical tide. The height of tide is a critical measurement in maritime navigation, as it directly affects the depth of water available for vessels to safely pass through or anchor in a given area. Tides are...

To steer or direct a vessel using its helm or steering apparatus. The apparatus or position used to steer and control a vessel, typically including the wheel or tiller and associated mechanisms.  The term "helm" is central to the operation and navigation of any vessel, whether a small sailing dinghy or a large motor yacht....

The individual responsible for steering and navigating a vessel, ensuring it maintains its intended course. A helmsman plays a crucial role in the operation of any vessel, whether it is a small boat or a large ship. This person is tasked with controlling the ship's wheel or tiller, which in turn adjusts the rudder to...

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,...