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Passing Under Bridges Safely

Passing Under Bridges Safely

According to the U.S. Coast Guard, a substantial amount of boating accidents involves bridges or surrounding structure. There are pilings, currents, divers, and other boats to consider. There are nuances with varying bridge types that need to be taken into account. To become comfortable passing under bridges, your best defense is knowledge.

Safely passing under a bridge will require different steps depending on the region, type of bridge and obstacles; however, one question remains consistent for all boaters approaching any bridge: is my boat too tall? Because of this, it is important that all captains know the air draft of their boat. Most manufacturers publish this information for each model, or boat owners can measure it themselves. Additionally, prior to any trip, captains should refer to local cruising guides and NOAA charts, adding bridge names (especially if a bridge name has changed recently), hours of operation, vertical and horizontal clearances, and recommended methods of contact to their trip log.

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Errors to Avoid

  • Lack of Communication
  • Being Too Close
  • Going Too Fast
  • Underestimating Currents

Luckily, law requires that the vertical clearance be posted on the right side of the bridge in the form of tide/clearance boards and/or gauges. The vertical clearance is the distance between the underside of the bridge and the surface of the water, measured at the center of the span using mean higher high water (MHHW).

For drawbridges, these postings represent the clearance when the bridge is closed to navigation. For some bridges, like arched and bascule, unless the clearance board specifically mentions that clearance is given at center, there’s a chance the clearance may be a little higher than what is posted, so always consult your charts, and check the tide level. You may have more room than you anticipate.

There are overhead lights that operate day and night, indicating the span of the navigable channel and whether it’s safe to pass under. The arrangement of the lights will vary per bridge, but as long as you stay centered with these lights, you can guarantee you are in the center of the channel. You can review the Coast Guard’s descriptions of these light arrangements here.

Requesting a Bridge to Open

If you know you will be approaching a movable bridge that you cannot pass through without requesting an opening, it is important to know if it is on a schedule, requires communication with the bridge tender, or a combination of both. Your local cruising guides will have this information. Some bridges open on-demand all year long, while some operate according to a schedule and may or may not open upon request outside of said schedule. Some bridges close during morning and evening rush hour traffic, some have specific hours during certain months, or only open on regular intervals, such as every half hour. There are usually white signs posted on the bridge that detail its hours of operation and procedures. It’s important to update yourself regularly, checking the Coast Guard’s Local Notice to Mariners, as some bridges may change their schedules from one season to another.

First things first, do not request an opening just because you don’t want to lower your outriggers, antennas, or similar components. If you can pass through easily by lowering or removing these, you are required to do so under penalty of law. Requesting an unnecessary opening is illegal and can result in a fine of up to $25,000.

It is customary to hail the bridge operator via VHF radio for an opening when you are in view of the bridge. It is best to be close enough to the bridge before calling so that you can put your radio on low power mode to reduce interference from other communications. If you don’t already have the contact information for the bridge on hand, you can keep an eye out for a blue sign with an icon of a phone receiver with a lightning bolt through it. This will display the VHF radio frequencies monitored by that particular bridge – usually 16, 13 or 9 (9 being the most used frequency in Florida). You will need to address the bridge by name and inform the tender of your vessel’s name, type, and heading. It is also recommended that you keep the radio tuned to the proper channel (if you already know it) during your transit, just in case of bridge emergencies that could keep you from passing through.

If the bridge operator does not respond to your request for several minutes, try again. If they are unreachable, you will have to resort to signaling by horn. The proper signal is one prolonged blast (4 to 6 seconds), followed within 3 seconds by one short blast (1 second). At this point, the operator should follow up with the same signal when they are getting ready to open the bridge. This will be followed by the danger signal of 5 short blasts when they are ready to close the bridge. If you are approaching a movable bridge that is already open, use the opening horn signal. If you don’t get a response within 30 seconds, you may proceed through. If, on the other hand, the operator is not able to open the bridge for you because of any number of reasons, they will signal “NO” by sounding the danger signal – 5 short blasts. In this instance, you will want to response with the same signal to let the tender know you understood their answer. It is important to use a closed-loop process with bridge operators so that both of you know you are in agreement of any actions taken. Do not turn off your radio or tune to another frequency until well after you are on the other side just in case the bridge needs to communicate with you while waiting or while you’re passing under.

If the bridge does not open and you don’t hear from the bridge in any way, you may have to call the bridge’s phone line directly or call the Coast Guard and request they reach out to the bridge. The phone numbers for bridges and the Coast Guard will be in your local cruising guide.

Ultimately, it is up to the discretion of the bridge operator to assess the need for an opening. So, if you arrive at the bridge opening at the time it is set to open and have not yet signaled for an opening, don’t assume the bridge will open at that specific time. The bridge tender may not know your intentions unless you ask properly.

Bridge Passing Etiquette

Remember to always have patience with movable bridges and their operators. For bridges that open on request, it is not uncommon to have to wait for another boat that may be approaching. Operators will often only open it once if they know more boats are coming. It’s also possible that bridges running on schedules won’t stay open for boats that are approaching but are still too distant. They have several variables to consider, like road traffic, weather and water conditions and the needs of many skippers. Keep all this in mind and do your best to be nice to the operators because at the end of the day, they are just people with a job to do.

When you are trying to pass under a bridge or waiting for one to open, be mindful of the traffic. If your air draft is well within the clearance limits, feel free to proceed but do so cautiously and in the order decided upon by the bridge tender or other skippers. If you must wait your turn once the bridge opens, keep the other boats in mind. The best rule of thumb is to stay in the back, far enough away to give them enough room to maneuver but close enough that you can get through in a timely manner so the bridge tender can get road traffic moving again. Keeping a safe distance also ensures that the current doesn’t force you to close to another vessel.

How do you know who has the right-of-way? Bridge operators will most likely not be involved in assigning right-of-way, partially because if it is a movable bridge, their visibility is limited when it is open. It is up to the captains of each vessel to follow basic customs and procedures and communicate with one another if necessary. Proceeding in a single-file line is optimal, leaving enough room for boats on the other side to also come through. With swing bridges, the naturally create two channels when open, allowing traffic from both sides to pass on opposite sides off the bridge.

For starters, boats moving with the current should always go first, as the current will be pushing them, therefore making it harder for them to stay put and easier to flow through the opening. Next, larger boats with less mobility should go ahead of smaller vessels. When in doubt, let others go first or do your best to attempt VHF communication with other boats in the area.

When you are getting close to a bridge, approach slowly. Speed limits reduce significantly near bridges for safety reasons. Also pay attention to any regulatory signs regarding high winds and tides. In case of inclement weather, some bridges may close or change their procedures. Upon arrival, be prepared to wait. While waiting, be aware of your position, making sure the current isn’t taking you too close to others or the bridge and pilings. If you are towards the front, stay away from the fender system until the bridge is fully opened.

When it is finally your turn to pass through, proceed at no-wake speed; you never want to run through on plane! There could be divers in the area, anglers in small boats near pilings and personal watercraft or other boats directly on the other side that would make this very dangerous. Stay alert to any boats coming off nearby ramps. You also need to watch out for bridge pilings and other structure, as well as the eddies around them. These could reduce visibility and affect your steering. Lastly, and possibly most importantly, pay close attention to the current.

The current typically picks up between bridge supports, and if you are traveling with the current, you will have less rudder control. The current can make it hard to avoid obstacles if you’re not cautious. Continue using any and all prudent signals or maneuvers when passing through to keep everyone safe. Once you are through, thank the bridge operator and maintain no-wake speed until well clear of the bridge. Check speed limit signs before resuming normal speed.

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Bonus Tip:

Watch out for power lines! They are marked on charts with listed clearances, but they can be easily overlooked by captains. Lines carry hundreds of thousands of volts across waterways and can be damaged by winds, rain, and lightning. If your boat comes into contact with a power line, don’t jump into the water. The contact with your boat can transfer into the surrounding water. Stay onboard without touching any metal and only leave the boat when you are fully clear of the line.

Happy Cruising!

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