(1) For the purpose of determining jurisdiction under this Act, every offence shall be deemed to have been committed, and every cause of complaint to have arisen, either—
(a) in the place where the offence or cause of complaint was committed or arose; or
(b) in any place where the alleged offender or person complained against may be.
(2) Where, in any proceedings under this Act, a question arises as to whether or not any ship or person is governed by this Act, such ship or person shall be deemed to be governed by this Act unless the contrary is proved.