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The Right Way To Navigate Bridges

At some point in your travels here and there by boat, you may have to request a bridge opening. Here's how to do it right.

Crowd of boats awaitingbridge opening

A crowd of boats wait for a timed bridge to open. (Photo: Mel Neale)

Whether you have to deal with bridges only occasionally or every day, you'll probably have to deal with them at least sometimes. If your boat has very little air draft, you may think there's not much to worry about. But there may be, and the issue of whether you're too tall to get under is only one of many. Here's what to expect when your way is blocked by spans of steel and cement with eighteen-wheelers flying overhead.

Barriers To Safe Passage

Obviously, you must avoid bridge pilings and the structure surrounding bridges. But you must also deal with eddies around them, which may affect your steering. Sailboats have particular issues because the wind may change, causing temporary calms or shifts. It is usually imprudent, and often illegal, to use sails to go through a bridge — unless that's your only means of propulsion. The pilings may obstruct vision, which is important regarding oncoming traffic, but also for avoiding small boats that often hang out around the pilings to fish.

Communities often build trailer ramps on one side of bridges. This means that small boats and skiffs may be blithely taking off from behind the pilings, heading into the path of boats coming through the bridge. Whether you're steering around pilings or through a span, all boats must be extra vigilant, using necessary signals and prudent maneuvering. Rules of the Road are very important, not to mention common sense.


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Who's On First?

Usually boats must funnel through a particular span of a bridge, which may require opening. Special right-of-way considerations may come into play. For example, if a boat is heading with the current, other boats heading into the current should normally let the boat being pushed come through first. Smaller nimble boats should generally stay out of the way of a large boat with more limited maneuverability. An outboard skiff darting around the bow of a ponderously moving tug and barge may be obscured from view of the pilothouse. This is true anytime, but particularly in areas of restricted maneuverability around a bridge. And what boater can possibly think his engine can never fail at just the wrong time?

Requested Vs. Scheduled

Many bridges must open to let taller boats through. Sometimes these bridges open on request if given proper signal, but many bridges only open at scheduled times. Always signal the bridge for an opening. Signals include horn blasts (usually a long and a short), but most boats call the bridge tender on the VHF. Bridges stand by on channel 9 or 13, depending on location. Call the bridge by its name (e.g., North Landing Bridge, Barefoot Landing Bridge, Seventeenth Street Causeway Bridge). Otherwise the wrong bridge may think you need an opening. Names of bridges and proper VHF channels are best found in updated guidebooks, where you will also find local rules and customs. Be aware that some bridge names may change. For many years, tugs going through the Atlantic Intracoastal Waterway (AICW) swing bridge south of Little River Inlet, South Carolina, called it, melodically, the "Little River Swing" (pronounced "swang.") Now the bridge is named the "Captain Archie Neil 'Poo' McLauchlin Swing Bridge" after a well-known local legend. The captain may be sitting in his favorite establishment watching as you go by.

Sailboat damaged from hitting a bridge

This sailboat was dismasted by a bridge. Fortunately, no one was injured. (Photo: Mel Neale)

It's often difficult to plan ahead for scheduled bridge openings because typically the current will change in the channel ahead. This is particularly true in areas where inlets or creeks run to larger bodies of water, such as the ocean. A creek may produce current, speeding you along, but as you pass its intersection, the current turns against you. People who simply plug distance to run into a chartplotter are often fooled.

Communication Is Key

Even if the boat ahead of you has requested an opening, you also should request one so that the bridge tender knows how many boats are coming through. We've known bridges to close on boats that haven't properly notified the operator. Often, when the bridge is in the open position, the bridge tender has limited visibility. Going through in a single file line is usually best because boats on the other side may also be coming through and space is limited.

Sometimes a bridge tender will instruct pleasure boats to wait for a tug and barge or other vessels because of that vessel's special needs or space limitation. Pay attention. Keep a VHF tuned to the bridge's operating channel well before you approach the bridge, as well as during the transit, because there may be special issues such as a malfunctioning bridge, a fire/rescue vehicle approaching on the highway, or other problems. If you know in advance, you can slow down and come through when the situation has cleared.

Into The Melee

When you reach a bridge, there may well be a crowd of boating traffic. If the bridge opens only on a schedule or is otherwise restricted (such as bridge work or emergency highway traffic), it is critically important to take into consideration the special maneuvering needs of other boats (including your own) when you're waiting in a crowd. Try to stay clear. For example, often a sailboat will have little control when backing or require a wide turning radius. Large vessels may have very little maneuverability in tight quarters. Often a tug with a barge must simply keep coming, unable to dodge around smaller boats.

Some vessels may have huge windage issues that make steering and positioning very difficult, especially if the wind is blowing across the channel or toward the bridge. Others, such as deep draft vessels, may be susceptible to strong currents pushing them toward the bridge and may need to face away from the bridge into the current or wind until the opening. Then it will have to turn, and there might not be room to do so within its turning radius. And just as boats have different handling characteristics, skippers have different skill levels. We've passed through many bridges over the years, and my favorite tactic is to remain at the end of the line to hopefully avoid trouble. Don't hang too far back, though, because the bridge tender has an obligation to get the highway traffic moving when he can.

To make matters worse, some bridges are situated poorly from a boat operator's perspective. The Wappoo Creek Bridge just south of Charleston, for example, spans a narrow channel that doglegs. The current is immense, and a large boat coming through on a fair tide may have trouble making the turn. And this bridge usually operates on a schedule. Check the charts to get the "lay of the land" long before you approach a bridge.

Watch Out For Power Lines

High-voltage power lines can carry hundreds of thousands of volts across rivers and bays. Power lines that cross navigable waterways are marked on charts with their clearance listed as from the height of mean high water (MHW), which is an average of several years of high tides. If the power lines are near a bridge, their lowest clearances are required to be higher than the bridge. However never take a chance with "close." Floods or surges can diminish the clearance. Also, voltage has been reported to jump from a power line to the mast top even though that mast top may not have actually touched the line. In addition, extremely hot days may cause some sagging, as could wind, lightning, or other damage to the supporting towers.

According to the U.S. Coast Guard, should your boat come in contact with a power line, don't jump into the water. The electrical charge may pass through your boat and electrify the surrounding water. The safest approach is to stay in the boat and avoid touching anything metal. Leave the boat only after it has moved away from the line.

— By Charles Fort

How High Is Too Low

Even if you think your boat's air draft can pass under a bridge, you still may need an opening. The theoretical vertical clearance of fixed bridges on the AICW is 65 feet (except for the 56-foot Julia Tuttle Bridge in Miami). But this is "sometimes." An unusually high tide, flooding from excessive rain, or storm tide can make it less. We've seen sailboats dismasted because they underestimated the clearance. Some sailboats will hang loaded dinghies or heavy jugs of water out to the side on a spinnaker pole and a halyard to cause a heel that will allow them through. (Not a good idea!) Most wisely go out to sea for that part of the passage or wait for sufficiently low water. Other waterways besides the AICW have different height restrictions. For example, 55 feet for the Florida Gulf Intracoastal Waterway and 49 feet for the Okeechobee Waterway.

Extra high tide

Extra high tides may mean trouble for tall-masted ­vessels. (Photo: Mel Neale)

There are usually tide boards at each bridge that show the vertical clearance at the center of the span (or wherever it's the highest), but sometimes these are damaged. It's difficult to "eyeball" vertical clearance. Standing on your deck and looking up creates an optical illusion making the overhead span seem much closer. Sometimes bridge tenders will help, but often they aren't allowed to because of the liability. If you can't clear the span and you're too close to the steel girders, the current or wind may prevent you from stopping in time.

Trawlers and other "short" boats may have a similar problem with a lower bridge, which they would normally need to open. If that bridge is timed, they may want to get under anyway and this requires absolute knowledge of your boat's air draft and the bridge's vertical clearance. The maximum vertical clearance of many bridges is typically at or near the center of the center span, not off to the side, although there are some significant exceptions to this. Bridge tenders sometimes tell captains to lower antennas and outriggers, etc. Requiring an opening just because you don't want to lower your antenna or outrigger isn't lawful.

It Takes Us All To Tango

When a bridge tender does try to be helpful or give you advice, remember that you're the skipper of your boat and are normally ultimately responsible. Many tenders have little actual experience running boats. Some also will become impatient with ignorant or impolite boaters. However, these incidents are not the rule and are often exaggerated. Bridge tenders must juggle many interests, all with the demands of the situation, which can include winds, tides, storms, currents, and poorly trained skippers. If you do have a problem, the U.S. Coast Guard has a "Bridge Office" in each district that you can contact. Typically bridge tenders are anxious to help, many going out of their way to do so. Some are boaters themselves. It takes all of us to make it work.

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Tom Neale

Technical Editor, BoatUS Magazine

One of the top technical experts in the marine industry, Tom Neale, BoatUS Magazine Technical Editor, has won nine first-place awards from Boating Writers International, and is author of the magazine’s popular "Ask The Experts" column. His depth of technical knowledge comes from living aboard various boats with his family for more than 30 years, cruising far and wide, and essentially learning how to install, fix, and rebuild every system onboard himself. A lawyer by training, for most of his career Tom has been an editor and columnist at national magazines such as Cruising World, PassageMaker, and Soundings. He wrote the acclaimed memoir All In The Same Boat (McGraw Hill), as well as Chesapeake Bay Cruising Guide, Vol. 1. These days, Tom and his wife Mel enjoy cruising their 2006 Camano 41 Chez Nous with their grandchildren.