18.—(1) The application of the seal of the Commissioners shall be authenticated by the signature of the convenor of the Commissioners or some other Commissioner authorised by the Commissioners to authenticate the application of the seal, and of the Harbour Master or some person authorised by the Commissioners to act in the place of the Harbour Master in that behalf.
(2) The Commissioners may authorise a person to act instead of the Harbour Master under this paragraph whether or not the Harbour Master is absent or incapable of acting.
(3) Any notice, licence or other document given or issued by the Commissioners shall, unless the contrary intention is expressed, be sufficiently authorised if signed by the Harbour Master or a duly authorised officer of the Commissioners.