Going Up: The lift bridge on the Cape Cod Canal. There's a sense of empowerment when it comes to getting a huge structure like this raised for your boat to pass under.

In North America we are blessed with a multitude of inland waterways that provide the cruising sailor with a unique opportunity to move around freely on the great "Blue Highway" in protected waters. Unfortunately, we have to share this continent with the larger part of society who scoot around in cars all day and insist that bridges be placed in all locations that will make their commute most time efficient. Sooner or later any sailor who wants to travel any distance must learn how to safely navigate through these great iron and concrete structures.

As sailors, Sue and I realize that we are fortunate that most places recognize the need for boat traffic, especially the commercial aspect, to be able to transit from point a to b. To accommodate these boats and not end up with snarling land traffic jams, many of the bridges are built at great expense to provide lots of clearance below. Others are constructed with the ability to open and allow boat traffic to pass through. Although navigating these various bridges is an initially intimidating experience, once you know the drill it's really quite easy. Here's the scoop on how to identify different bridges, communicate with the bridge tenders and safely navigate through each.

Let's look at fixed bridges first. It's a good idea to double check the chart and confirm that you can safely pass under the structure while you are still some distance from the bridge. To determine this, you will need to know the height of your mast over water before you leave the dock. The vertical clearance for a bridge is normally listed beside the bridge symbol on the chart. To confuse matters though, the stated clearance on the chart may differ from the actual clearance on any given day. In coastal areas, tides and wind can exert a great influence on water levels and thus bridge clearances. Inland bridges are similarly influenced by winds, recent rainfall amounts, and various other factors like the demand for hydroelectric power. If you are uncertain whether or not you can pass under a bridge, proceed with caution and look for other information. Frequently, you will find a minimum height clearance indicator mounted near the bridge. This vertical gauge looks like a big yardstick and indicates the distance between the water level and the underside of the fixed structure.

Sixty two feet and change of clearance under this fixed bridge. Narrow waterways can cause the currents to run faster and bridge structures in the water and make for some lively moments at the helm.

If you are approaching a fixed bridge while sailing, you'll want to determine before you get too close to the bridge if you can safely continue under sail, or whether you'll need to crank up the engine and motor through the center span. Take into account the amount of boat traffic, the width of the span, the speed and direction of the current, and finally the wind speed and direction. The water around the bases of bridges often swirls in an ever-confused pattern due to the current flowing around the pilings. These swirling waters can push a sailboat without good headway sideways into part of the bridge. And finally the wind always seems to suddenly shift or momentarily die just as you are entering the span--anticipate and be ready to make instantaneous changes in sail trim or heading.

Every situation is unique and requires an independent analysis of how to best proceed. On Serengeti when we decide to sail under a fixed bridge, we start the engine and have it idling just in case. We also disengage the autopilot if we've been using it, and hand steer through the bridge. Hand steering allows us to react quickly to anything unexpected. Hand steering is also important because bridges and autopilots aren't very compatible. The metal in most bridges (even concrete bridges) can influence the fluxgate compass of an autopilot resulting in a violent and unintentional course change as you pass under the span - not exactly what you want to have happening at that particular moment.

Opening bridges may be on request, may be closed during rush hour, or may be on a set schedule. Research before your journey begins can alleviate waiting around for a bridge to open.

When it comes to navigating an opening bridge it sometimes requires a little more research. You'll first need to know its operating schedule. Some bridges open "on request" meaning that if you hail them on the VHF radio, they'll likely open for you right away. In areas of congested car traffic some bridges have a set schedule as to when they allow boats to pass. It's common to see openings on the hour, every half-hour, and sometimes every 20 minutes. These same bridges may be restricted to no openings for an hour or so during rush hour traffic in the mornings and again in the afternoon. Knowing these restrictions can save you hours of frustration waiting in sometimes tight quarters. For example, when we travel the ICW south in Serengeti, we always leave our anchorage in Norfolk VA before first light. This extra-early departure allows us to pass through and be south of the bridges that close down completely for the morning commute.

Bridges do not open automatically as a boat approaches, meaning it's necessary to request a bridge opening. Use your VHF radio to contact the bridge tender who is sitting in a little windowed house on top of the bridge. Most bridgetenders monitor Channel 13 or 9, depending upon which state they are in, freeing up channel 16 for more important traffic. In many cases several bridges are very close together, so you'll need to know the specific name of the bridge you are approaching in order to communicate with the tender. Some charts list the name of the bridge, but inexplicably most do not. For these bridges, you can be prepared in advance by using a cruising guide for the local area. In certain areas you will find both the name of the bridge and the channel(s) that the bridgetender monitors posted on the bridge itself.

A sample hail for an opening would go as follows: "Pleasant Street Bridge, Pleasant Street Bridge, this is Serengeti." When the bridge tender responds, you continue, "I'm a south bound sailing vessel and would like to request an opening." The bridge tender then has a chance to tell you if there are any delays, any commercial traffic you should know about or if you should simply keep coming full steam ahead. Commercial traffic always has the right-of-way over recreational traffic at bridges. For these communications, a VHF radio mounted in the cockpit or use of a handheld VHF are vastly superior to having to go below on your boat. Most bridge opening requests are made once you have the bridge in sight and are within a quarter mile of the bridge. Once you've made a bridge opening request, you must remain on that VHF channel until you have completed your passage in case the bridge tender needs to contact you again.

If you don't have a VHF radio onboard, you can request a bridge opening by sound. One prolonged blast from a horn, followed within three seconds by one short blast will do the job.

A swing bridge, pivoting on a center point. The rule for this type of bridge, and all bridges, is to stay clear until they have fully opened.

Once your opening has been arranged, there are a few more considerations for a safe passage. To save on costs, opening bridges are usually built where the water narrows a little. This means that the tides and currents tend to run faster than in the more open parts of the waterway. Any time you are sailing into new territory you should use a current chart. On this chart you will find each bridge's location along with information that will tell you whether it is a fixed bridge or an opening bridge. Again, be prepared for swirling underwater forces to affect your steerage when proceeding through the bridge. Above the water, large bridge structures can cause unpredictable shifts in the wind. Keep a keen eye out for other boat traffic, and proceed with caution. If going through the bridge opening with other boats, be sure to keep a safe distance apart. Since it's harder to steer when going with the current than against it, boats moving with the current have the right-of-way. Attempting to sail through an opening bridge is a recipe for disaster. Always plan to drop all sail and proceed under power.

Once through the bridge, a friendly wave to the bridge tender, or a quick thank you on the radio is appropriate.

Here's a quick overview of the four different types of opening bridges you're likely to encounter: