Glossary Archive

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,...

An opening in the deck or bulkhead of a vessel, typically covered by a door or lid, providing access to the space below. A hatch is a crucial feature on any vessel, serving as an access point between different compartments or between the deck and the interior spaces below. Hatches are designed to be watertight...

To pull in, usually a sheet, halyard or anchor line

The International Maritime Signal Flag Hotel. Meaning I have a pilot on board.

Used in satellite navigation and positioning systems to quantify the accuracy of horizontal position measurements. It is a unitless factor that indicates the geometric quality of the satellite configuration in relation to the receiver's position. A lower HDOP value indicates a more accurate horizontal position, while a higher HDOP value indicates a less accurate position...

Head (heads) refers to the toilet or bathroom on a boat. The heads on a boat may be equipped with a marine toilet designed to safely handle waste while out on the water.

Head is the term for the topmost part of a sail where the halyard is attached to enable the sail to be hoisted and lowered.

The direction in which a vessel's bow is pointed at any given moment, typically measured in degrees relative to true north or magnetic north. A vessel's heading is a critical concept in navigation, as it indicates the direction the boat is currently facing, regardless of external influences such as wind, current, or waves. It is...

A coastal landform characterised by a high, narrow piece of land that juts out into the sea, often forming a prominent point along the shoreline. A headland is a significant geographical feature found along coastlines, where the land extends out into the sea, creating a distinctive point or promontory. These formations are typically composed of...

Any sail set forward of the mainmast on a sailing vessel, typically used to enhance speed and manoeuvrability. A headsail is a critical component of a sailing vessel's rigging, positioned forward of the mainmast and often attached to the forestay, which is a wire or rope running from the top of the mast to the...