The diffusion of a solvent through a semi-permeable membrane which separates two solutions of different concentrations, such that the concentrations are equalized.

Osmotic power, salinity gradient power or blue energy is the energy available from the difference in the salt concentration between seawater and river water.

In a direction away from the centerline of the ship.

A survey intended to report on the overall condition of the hull structure and determine the extent of additional close-up surveys.

Accidental escape of oil from a tank when it gets too full because pumping was not stopped in time.

Pipes provided to prevent, during filling operations, an overload greater than the one corresponding to the test pressure prescribed for the compartments.

A structure used in electrical power transmission consisting of uninsulated electrical cables being suspended by a tower.

A method to transmit electricity through uninsulated cables that are suspended above ground from a tower.

The welding position in which welding is performed from the underside of the joint.

Physical safety markers placed on overhead transmission cables to aid in the sighting of the cables. Often used near airports, across rivers or other areas close to flight paths.

A load which is in excess of the rated capacity of the unit or device, e.g. an engine, motor, electric cable.

A device which interrupts the current flow if it reaches an excessive value.

The Overnight capital cost is a term used in the power generation industry to provide a simplisitic comparison of the costs of building power plants.

A manual means of changing the operation of an automatically-controlled device or a system.

Each main propulsion engine which can be declutched or which drives a CP propeller is to be fitted with an overspeed device so adjusted that the speed cannot exceed the maximum rated speed by more than 20%.

Overtopping devices are long structures that use wave velocity to fill a reservoir to a greater water level than the surrounding ocean.

When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage.

Oxidation is the loss of electrons or an increase in the oxidation state of an atom, an ion, or of certain atoms in a molecule.

Gas (SG) engines and multi-fuel (DF) engines can be equipped with oxidation catalysts for the abatement of carbon monoxide (CO) and/or hydrocarbon (HC) emissions.

Oxygen is the chemical element with the symbol O and atomic number 8.