In this Act—

• " harbour " and " harbour authority " have the respective meanings given to them by section 57 of the [1964 c. 40.] Harbours Act 1964;

• " harbour master " includes any dock master or pier master who is not a subordinate of a harbour master and any deputy or assistant of a harbour master or of such a dock master or pier master ;

• " vessel" includes—

  1. a

     a ship or boat, or any other description of craft used in navigation;

  2. b

     a rig, raft or floating platform, or any other moveable thing constructed or adapted for floating on, or partial or total submersion in, water ; and

  3. c

     a seaplane, a hovercraft within the meaning of the [1968 c. 59.] Hovercraft Act 1968 or any other amphibious vehicle.