law: 27. Certificates to be held by master and engineer of vessel of less than forty horsepower.-
  An inland 1[mechanically propelled vessel] having engines of less than 2[forty] nominal horse-power shall not proceed on any voyage unless she has-
  (a) as her master a person possessing a scrang's certificate granted under this Act, or any certificate referred to in clause (a) of section 26, and
  (b) as her engineer a person possessing a second-class engine-driver's certificate granted under this Act, or any certificate referred to in clause (b) of section 26: Provided that a 1[mechanically propelled vessel] shall be deemed to have complied with this section if she has as her master and engineer a person possessing both a certificate referred to in clause (a), and a certificate referred to in clause (b), of this section.