A term used to describe the time at which a vessel is no longer meeting the terms of readiness for a shipment and is therefore no longer earning revenue during that time. Some situations which can cause offhire periods are holds not clean, dry, free from infestation; engine failure, cannot sail due to crew problem or shortage. Etc.. When a vessel's condition changes back to meet the contract or charter party terms it is placed back on-hire. In some cases such as poor engine perfoprmance which extends the charter and adds expenses a claim for partial offhire may be made.
A system of gears which alter the ratio between the revolution of the engine and the propeller shaft so the propeller operates in a relatively efficient speed range. By using a gearbox the engine and the propeller shaft will revolve at different speeds.
One of a series of numbers (constituting the PN, or performancenumber, scale) used to convert fuel antiknock values in terms of a reference fuel into an index which is an indication of relative engine performance; used mostly to rate aviation gasolines with octane values greater than 100.
A clutch that allows the driven shaft to turn freely only under certain conditions; for example, a clutch in an engine starter that allows the crank to turn freely when the engine attempts to run.
A fourstroke-cycle internal combustion engine having its valves located in the cylinder head, operated by pushrods that actuate rocker arms. Abbreviated OHV engine. Also known as valve-in-head engine.
A gear train in which the angular velocity ratio of the driven shaft to driving shaft is greater than unity, as when the propelling shaft of an automobile revolves faster than the engine shaft.
An instrument which makes a plot of pressure in the cylinder of an engine as a function of piston (or volume) displacement, making use of magnification by optical systems and photographic recording; for example, the small motion of a pressure diaphragm may be transmitted to a mirror to deflect a beam of light.
