It shall be unlawful for any person operating any boat, except a sailboat, to permit any person to ride, sit, or stand, or for such person to ride, sit, or stand, upon either the gunwale of a boat or upon the decking over the bow of a boat unless such boat is provided with adequate guards or railings to prevent such persons from being lost overboard. The provisions of this section shall not be construed to mean that a person on a boat may not stand on the decking of the bow of the boat to moor or cast off or for any other necessary purpose. (§ 8, Ord. 360)