The draw of the Winneconne highway bridge, mile 2.4 at Winneconne, shall open on signal; except that, from 11 p.m. to 7 a.m. from May 1 through October 31, at least two hours notice is required and, from November 1 through April 30, at least 12 hours notice is required. At all times, public vessels of the United States, state and local vessels used for public safety, and vessels in distress shall be passed as soon as possible.