The master or owner of any ship or vessel appearing in distress, and in want of a pilot on the coast shall pay to any bar pilot who has exerted himself for the preservation of the ship or vessel, such sum for extra services as the owner or master and pilot can agree upon, provided the pilot boards said ship or vessel or assists the same from some other boat or vessel.  In case no agreement can be made the Board of Commissioners for the Port of New Orleans shall determine what is a reasonable reward, which the bar pilot shall be entitled to collect.