Glossary Archive

The outer hull of a vessel above the waterline, extending from the deck to the water's edge. The term "topsides" is a fundamental concept in marine terminology, describing the portion of a boat or ship's hull that is visible above the waterline. This area plays a critical role in the vessel's overall design, functionality, and...

Sea area of the Met Office Shipping Forecast. Located off the southern coast of Spain, near Cape Trafalgar. Named after Cape Trafalgar (site of Nelson’s victory, 1805), Trafalgar sees frequent southwesterly gales and rough seas, especially after October. Historical accounts note strong headwinds during the Battle of Trafalgar itself.

A navigation system designed to organise the flow of vessel traffic in congested or high-risk areas, ensuring safe passage by separating opposing traffic streams. A Traffic Separation Scheme (TSS) is a regulatory measure established by the International Maritime Organization (IMO) to enhance maritime safety in areas where vessel traffic is dense or where there is...

An alignment of two fixed objects seen from the vessel. This can be used as a simple and reliable visual reference for position, clearing dangers or checking whether a vessel is on a planned line. When the two objects appear directly in line, the vessel lies somewhere along that line of position. Useful pairs might...

The transom is the flat, vertical surface at the back of a boat. It is typically where the outboard motor or stern drive is attached to a motor vessel. Sailing vessels often have a transom that can fold down to create a bathing platform. The transom provides structural support and stability for the vessel and...

A sliding fitting or track on a sailing vessel, used to adjust the position of a sail's sheet or other control lines for optimal sail trim. A traveller is an essential component of a sailboat's rigging system, designed to provide precise control over the angle and tension of the mainsail or other sails. It typically consists of...

Masthead light combining red, green and white lights in one unit.

Trim is the adjustment of a boat's sails, weight distribution, and angle relative to the water to optimise performance, balance, and stability. Trim is a critical concept in boating that refers to how a vessel is balanced and positioned in the water and how its sails or engine power are adjusted to achieve optimal performance....

A vessel with three hulls

Flaps which can be pushed up or down to adjust the angles of the bow and heel on a motor vessel