Glossary Archive

This shape indicates a space, usually between words. The same shape is also used for Rest (Flag Semaphore) & Ready (Flag Semaphore).

Any long, sturdy pole or beam used on a ship to support sails, rigging, or other equipment. Spars are typically made of wood, metal, or composite materials and are essential to a ship’s rigging system. There are several types of spars on a vessel, each serving different functions in relation to the sails and mast....

The speed achieved along the intended track over the ground. This accounts for the effect of tide, leeway and the vessel’s actual movement relative to the planned route. A boat may show good speed through the water while making poor progress towards the destination if it is being set sideways. This measure helps the skipper...

The actual velocity of a vessel relative to the Earth's surface, accounting for the effects of currents, tides, and other environmental factors.  Speed Over Ground (SOG) is a critical navigational term in maritime operations, representing the true speed at which a vessel moves over the Earth's surface. Unlike Speed Through Water (STW), which measures the...

The velocity at which a vessel moves relative to the water it is travelling through, excluding the effects of current or tidal flow. Speed through water refers to the rate at which a vessel progresses through the water itself, as opposed to its speed over the ground, which includes the influence of currents and tides....

Reducing power in a sail by allowing some wind to escape. This is usually done by easing a sheet, changing course slightly, or adjusting sail shape so the sail is not fully loaded. It can reduce heel, make the vessel easier to steer, or provide a short-term response to a gust. It is often used...

A large, lightweight, and often colourful sail designed for use when sailing downwind, typically set forward of the mainsail to maximise speed and efficiency. A spinnaker is a specialised sail used on sailing vessels to take advantage of wind coming from behind the boat, known as downwind sailing. It is distinct from other sails due...

A spar used on sailing vessels to control one clew of a spinnaker sail when sailing downwind. A spinnaker pole is a key piece of equipment used in sailing, specifically when deploying a spinnaker sail, which is a large, lightweight sail designed for use when sailing with the wind behind the boat. The spinnaker pole...

A projecting shoal or strip of land connected to the shore

A method of joining two ropes or lines by interweaving their strands to form a strong, secure connection. A splice is a fundamental technique in marine ropework, used to create a permanent or semi-permanent connection between two ropes or to form a loop (eye) at the end of a rope. Unlike knots, which can weaken...