http://www.legislation.gov.uk/ukpga/1985/22/section/6Dangerous Vessels Act 1985An Act to empower harbour masters to give directions to prohibit vessels from entering the areas of jurisdiction of their respective harbour authorities or to require the removal of vessels from those areas where those vessels present a grave and imminent danger to the safety of any person or property, or risk of obstruction to navigation; to enable the Secretary of State to give further directions countermanding those first-mentioned directions; and for connected purposes.1985-05-23texttext/xmlenStatute Law Database2015-09-10Expert Participation2015-03-12 6No directions under section 1 of this Act shall apply in relation to—aany vessel belonging to Her Majesty, or employed in the service of the Crown for any purpose, including any such vessel in the possession of a salvor; orbany vessel which is a pleasure boat of 24 metres or less in length.