Bridges—Know Your Way Through
As a kid cruising along the New England coast in a forty-foot sailboat I always found bridge passages to be exciting and full of mystery. The bridges had different characteristics depending on their location and purpose, and each approach had me on the edge of my seat wondering if we were going to make it. I often climbed to the top-spreaders on the mainmast to get a better feel for the passage. As I grew older I realized how much navigation and boat handling was involve to make these passages safely.
Many boaters have had to pass under a bridge at one time or another in their day. You’ll find bridges on major and minor rivers, narrow sections of lakes and over saltwater bays. Often it’s a routine event—you have a small powerboat and the bridge is long and high and the passage is simple. But many bridges can offer a challenge; swirling currents, tight entries, lots of traffic. Here are some basics on approaching and passing under bridges over our waterways.
First of all, there are the navigational considerations. A thorough review of the local chart should be accomplished to prepare for the approach to any bridge. Taking note of the buoy locations and meanings, water depths and range markers is best done well in advance if it’s your first time. If the currents are tricky and underwater obstructions are abundant it would be good to pick up local knowledge from other boaters or a local marina. Getting into a tight spot at a bridge with a lot of current and little room to maneuver is a bad situation to be in. A bridge’s piers are unyielding if you are unfortunate and hit one. So, prepare for the passage with every bit of information you can.
It can’t be overstated that you should know your bridge and the rules that apply to passing under it. Bridges will have lights and often signs to provide guidance. Lights show not only that the bridge is there (very helpful at night), but also how to pass the bridge. Red lights show the location of the bridge piers and supports, and may also be used to show if a lift-span or draw-bridge is closed to traffic. Green lights mark the centerline of the navigation channel for a fixed bridge, and also whether a moveable span is open to traffic. Three white lights stacked vertically indicate the preferred navigation channel if there is more than one.
Signs will state information like hours of passage, radio frequencies and any cautionary information. If you see a sign it’s a good idea to get the binoculars out and read it before you get up too close. You should also be on the alert for clearance gages which will indicate how much headroom you’ll really have when you pass under. Be sure to read these gages carefully, know your boat’s height above the waterline, and make adjustments based on any wave action which will cause your boat’s height to vary.
Finally, consulting a local waterway guide will give you a heads-up on what to expect at a bridge and, along with any Notices To Mariners, give you everything you need to be comfortable with the approach and passage.
If a bridge is a fixed span, then your operations are simpler—no asking for a bridge to open nor worry about hours of operation. Know your approach, read any signals available at the bridge, watch for traffic and proceed with caution. Monitor your radio and signal your intentions to other boaters if necessary. If there is a lot of current, keep your headway up to maximize your maneuverability until well past the opening. Avoid passing under at the same time as another vessel unless you have lots of sea-room.
If the bridge is a moveable span, you’ll need to ask for the bridge to open. There are two usual ways to contact a bridge tender to request an opening—sound and radio.
If the bridge does not indicate radio communication is available you’ll need to use sound signals. The required signals are:
Opening: one long horn blast followed in three seconds by one short blast. The bridge tender will answer with the same signal, at which point you can proceed. If the bridge is open but you receive no answer, wait 30 seconds, then proceed with caution through the opening. Watch for other boats doing the same!
Cannot Open or Immediate Closure: if the bridge can’t be opened or, if already open, has to close immediately, the bridge tender will signal with 5 short blasts in rapid succession. Be prepared to maneuver, so know who’s behind you!
If the bridge has radio communication you will likely find the channel listed on a sign. But if not, use VHF channels 13 or 16 for most areas. Florida, South Carolina and Georgia use channel 9, but again, double check any local guides if you’re not sure.
There are also visual signals you can use if needed; a white flag (daytime) or white light (night) can be used if visible for a half-mile. Signal the bridge until you get a reply. A repeat of your signal by the tender means "come ahead". A red signal indicates no passage or bridge span about to close.
Bridges along our waterways are often things of beauty and inspire awe when passed under. Know your approach, know the rules, stay alert and enjoy the passage. And, by all means, wave thanks to the bridge tender on your way through!
(For more information on bridge passages, go to the US Coast Guard Boating Safety website (www.uscgboating.org), or consult the latest volume of Chapman Piloting and Seamanship. Information for this article was acquired from each of these sources.)