Ships are potentially dangerous working environments and over many years, international guidance and regulations have been developed to protect the lives and wellbeing of the crews, cargoes, ships, property and the environment. Ships have to meet specified standards of design, construction and equipment. Seafarers must reach specified levels of training and qualification. Appropriate management systems have to be in place.

 Compliance with all of these requirements is evidenced by certificates. Some of these are displayed on bulkheads around the ship and others are kept in the senior officer’s offices.

 All certification is subject to renewal at given periods of time and many are subject to interim survey or inspection to ensure continued compliance. On this basis the period of validity for most certification (including officers’ qualifications) is five years.