Section 12: Production of certificate on demand.

[Omitted] The owner or owners or commander of every such vessel employed as aforesaid, fishing-vessel and harbour-craft shall produce, on demand thereof by any officer of the Customs [Omitted] or by any officer of the [Omitted] Navy, the certificate so directed to be applied for and obtained, in respect of such vessel employed as aforesaid, fishing-vessel or harbour- craft, as above mentioned.