Glossary Archive

A sealed onboard container designed to temporarily store wastewater, such as sewage or greywater, until it can be properly discharged at a designated facility. A holding tank is an essential component of a vessel's waste management system, particularly on boats equipped with toilets (marine heads) or sinks. Its primary purpose is to collect and store...

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...

A U-shaped flotation device designed to be thrown to a person overboard to provide buoyancy and aid in rescue. The horseshoe lifebuoy, also known as a horseshoe ring or horseshoe buoy, is a critical piece of safety equipment commonly found on recreational and commercial vessels. Its distinctive U-shape allows it to fit snugly around the...

Pronounced: hoh-TELL The term for the letter H in the NATO Phonetic Alphabet.

Attachments of stays to masts.

Any personal flag or club flag flown from starboard spreaders or flagstaff.

The watertight body or shell of a boat or ship, excluding the deck, rigging, and other superstructures. The hull is the fundamental structure of any vessel, designed to provide buoyancy and stability while keeping the water out. It is the part of the boat that makes contact with the water, and its shape and construction...

The maximum efficient speed of a displacement-hulled vessel.

Sea area of the Met Office Shipping Forecast. Lies off the east coast of England, near the Humber Estuary. Named for the Humber Estuary (possibly Celtic for “big water”), Humber sees cyclonic winds of Force 3–5 with occasional sudden gales and tidal surges. The 1953 storm surge overtopped banks, causing widespread damage and leading to...

Beaufort Scale - Force 12 (Hurricane Force 12) Hurricane-force is a term used to describe wind speeds equal to or greater than 64 knots (74 miles or 119 kilometres per hour), the minimum wind speed threshold for a storm to be classified as a hurricane. Winds of this magnitude are capable of causing significant damage...