Heavy crude oil is highly-viscous oil that cannot easily flow to production wells under normal reservoir conditions. It is referred to as "heavy" because its density or specific gravity is higher than that of light crude oil. Heavy crude oil has been defined as any liquid petroleum with an API gravity less than 20°.

Heavy fuel oils are blended products based on the residues from refinery distillation and cracking processes.

Heavy industry is an industry that involves one or more characteristics such as large and heavy products; large and heavy equipment and facilities or complex or numerous processes.

The FAIRPLAYER was built by the Damen Shipyards Galati, Romania. The ship was completed entirely in Galati, except for the fitting of the cargo cranes.

A cargo-handling device for heavy large items.

Specialized ships capable of transporting non-standardized heavy cargoes. They can be subdivided into four main categories: project cargo ships, open deck cargo ships, dock ships, and semi-submersible ships.

The system used to move heavy ship modules. The first STS was installed in Bremer Vulkan Yard, Germany.

Heavy running occurs when engines reach the maximum continuous rating before they reach full rev/min.

Heavy water (deuterium oxide) is a form of water that contains only deuterium rather than the common hydrogen-1 isotope that makes up most of the hydrogen in normal water.

Damage caused to a ship as a result of sailing in heavy weather. Typically bending and buckling of forepeak, side shell and bottom structure.

The inclination of a ship to one side (see list). Also the corner of an angle, bulb angle or channel, commonly used in reference to the moulded line.

Coefficient used to compare propulsion efficiency at the same Froude number. The higher the Heickel coefficient the better the performance (less power required to reach the same speed).

The blades of a Darrieus turbine can be canted into a helix, e.g. three blades and a helical twist of 60 degrees. Since the wind pulls each blade around on both the windward and leeward sides of the turbine, this feature spreads the torque evenly over the entire revolution, thus preventing destructive pulsations.

The wires are placed helically in every layer.

A helideck including any refuelling and hangar facilities, (SOLAS).

A purpose-built helicopter landing area located on a ship including all structure, fire-fighting appliances and other equipment necessary for the safe operation of helicopters, (SOLAS).

A plane mirror device that moves with the sun to continuously direct solar power to a receiver.

Technology that utilises Heliostats that contain a mirror to redirect sunlight to a collector or target.

A tiller or a wheel generally installed on the bridge or in the wheelhouse of a ship to turn the rudder.

A double layer (DL, also called an electrical double layer, EDL) is a structure that appears on the surface of an object when it is exposed to a fluid.