Traveling the inland waterways can be a pleasant experience but can also bring some special challenges especially for larger boats and sailboats. Dealing with draw bridges takes some knowledge of how the system works and knowing what you are looking for, especially at night.
Nautical charts only tell you that there is a bridge and what the horizontal clearance (width) and vertical clearance (height) are. The vertical clearance is the one you are probably going to be most concerned with, i.e. will you fit under the bridge or will you have to open it?
You should consult your chart for the note on heights; most will show minimum vertical clearance at mean high water. That means if you are at the bridge at any time other than high tide, you should have more clearance than shown. (You’ll be able to tell exactly when you get there.) You should, prior to planning a trip, consult the Coast Pilot or Cruising Guides for the area you will be traveling and make notes in your trip log concerning bridges including the name of the bridge, hours of operation, recommended method of contact, etc.
As you approach a bridge there are several thing that you should look for. You should check the right side of the bridge opening for the “clearance board”. This will give you the minimum clearance, in feet, from the water level to the bridge structure. This will determine whether you can clear the bridge or will need to have it open. Speaking of opening a bridge, you should know the vertical height of your boat prior to getting to the bridge. Do not cause unnecessary openings, it is illegal!
For additional information on boating and bridges look at one of the many published articles at http://www.boatsafe.com/nauticalknowhow/bridge.htm.
Apparently, the boat in the video below did not know the vertical height of the boat.