HR glossary of terminology

# a b c d e f g h i j k l m n o p q r s t u v w x y z

OBO Ship

Short for ore-bulk-oil the OBO Ship or OBO Carrier is a multipurpose vessel which transports ore heavy dry bulk goods and oil.


An Oiler is an unlicensed crew member who works in the engine room /department in this entry level cargo ship job. The Oiler greases and oils bearings and moving parts of the main engine and auxiliaries. However the majority of these tasks are now done automatically and it is the oiler’s responsibility to ensure that everything is running correctly.


An Officer is any licensed members of the ship's crew. A licensed mariner is a seafarer who holds a license from a maritime authority enabling them to hold senior officer-level positions aboard a vessel.

Oil Record Book

The Oil Record Book is a book or log kept by the Master of an oil tanker in which every discharge or leakage or spillage of oil must be recorded.

Oil Tanker

An Oil Tanker is a vessel that has been designed for the transportation of oil in bulk. An Oil Tanker’s cargo space consists of several or many tanks and tankers load their cargo by gravity from the shore or by shore pumps and discharge it using their own onboard pumps.

Open Registry

Also known as ‘Flag of Necessity’ or ‘Flag of Convenience’ an Open Registry refers to flagship registry systems in some countries that allow vessel owners to register their ship under the flag of that country. This is normally done so that the shipowner can take advantage of favorable laws or rates that there own country does not have.

Ordinary Seaman

An Ordinary Seaman is a member of the Deck Department. They are a rank lower than an Able Seaman but will still be expected to know the ins and outs of their job. An OS’s duties and responsibilities include cleaning and maintenance supervising lower ranking deck crew and assisting with operations such as docking undocking line handling and the loading and unloading of cargo.

Ore Carrier

An Ore Carrier is a vessel designed for the transportation of ore. Ore has a high density therefore ore carriers have a relatively high center of gravity to prevent them from rolling in heavy seas.

Ore-Oil Carrier

Similar to an OBO ship which carries ore bulk goods and oil an Ore-Oil Carrier or Oil-Bulk Carrier transports either oil or ore in bulk.

Outfall Buoy

An Outfall Buoy or Outfall Mark is a buoy that marks where a drain or sewer discharges into the sea. 


Overtonnaging is a term used to refer to a situation when there are too many ships overall or in a particular area or sector for the amount of available cargo.