Every person licensed to keep a toll ferry shall give bond, with two or more sufficient sureties, to be approved by the president and clerk of the board of supervisors, payable to the county, and in a penalty of not less than five hundred nor more than two thousand dollars, to be fixed by the board, conditioned to constantly provide and keep good and sufficient boats and appliances for the speedy and safe transportation of persons and property over the stream, to provide safe landings for the ferryboat, and in all things to comply with the law and the reasonable orders of the board regulating the keeping of the ferry; but saving to the keeper a reasonable time within which to repair damage done by sudden freshet, storm, or other unforeseen accident.