Commentary on Sections Part 5 - General Section 49: Power to detain vessels, etc.
This section provides that a vessel can be detained in port if an inspector believes that an offence is being or has been committed on board. A certificate specifying this must be presented as soon as practicable to the person in charge of the vessel. The Department may make regulations extending this section to aircraft or hovercraft, or make other provision for detaining aircraft or hovercraft as appropriate.