A free-floating decompression chamber for human occupancy. It can be maintained with gas mixture under a pressure. In case of emergency, it is launched from a vessel, a rig or a platform in distress and may drift free.

A self-propelled lifeboat intended for human occupancy in saturated conditions.

A chamber or combination of chambers, intended for manned operation at internal pressure above atmospheric.

A system allowing for the divers under pressure to be safely evacuated from a ship or floating structure to a position where decompression can be carried out.

The large hydrodynamic and cavitation tunnel of the Hamburg Ship Model Basin HSVA.

Cargo tanks on oil tankers are loaded to 98% and in some cases 99% of capacity with the oil level well above the sea level.

A part of the liferaft lashing used for automatic liferaft release. At up to 4m water pressure activates release mechanism and the liferaft is free to float clear to the surface.

A series of graphs drawn to a vertical scale of draught and a base of length, which gives values such as the centre of buoyancy, displacement, moment causing unit trim, and centre of flotation.

A vessel equipped with hydrographic survey equipment to determine underwater topography in order to produce high-precision charts.

A vessel with underwater wings (hydrofoils) fitted below the hull. The dynamic lift of hydrofoils keeps the hull clear of the water surface while underway.

Hydrofoil craft that receives a portion of its lift from a single buoyant pod located below a traditional upper hull. The foils are attached to the pod or “lower hull” which is connected to the upper hull by one or more low-waterplane area struts.

An organic compound consisting entirely of hydrogen and carbon.

The method used for cleaning of the surface to be repaired. The degree of cleaning depends on the pressure of the water jet.

Compounds containing hydrogen, fluorine, chlorine, and carbon atoms. Although ozone depleting substances, they are less potent at destroying stratospheric ozone than chlorofluorocarbons (CFCs).

A mechanism for driving hatch covers to the open or closed position. It uses a hydraulic motor attached to the coaming to power a pinion which drives a rack fitted to the panel.

A device which converts hydraulic fluid power into mechanical force and motion. It usually provides rotary motion.

The terminal point of a water main with fittings for the attachment of a hosepipe.

Deflections of plating in between supporting grillage.

A criterion used in the design of offshore oilrigs and meant to represent most severe conditions that may occur once in a hundred years.

A system of measuring stresses in selected locations of a hull girder. The system usually includes a database in which measurements are recorded for subsequent reference.