law: Indian Ports Act, 1908
  48. Port-due not to be chargeable in certain cases 
  No port-due shall be chargeable in respect of- 
  (a) any pleasure-yacht, or
  (b) any vessel which. having left any port., is compelled to
  
  re-enter it by stress of whether or in consequence of having sustained any
  
  damage, or
  (c) any vessel which, having entered 59[any port 60[in
  
  the territories which, immediately before the 1st November, 1956, were comprised
  
  in the States of Madras and Andhra] or the Port of Gopalpur in the State of
  
  Orissa], leaves it within forty-eight hours without discharge or taking in any
  
  passengers or cargo.