One of Alfred Tennyson’s best-known poems uses a bar crossing as a metaphor for the process of dying. Tennyson’s comparison in Crossing the Bar is fitting because transiting a bar between an ocean and a river or harbor can be one of the most intimidating experiences a boater faces. More than a few people, myself included, have seen the steep seas on a bar and wondered if this might be the end.

A bar is a shallow area of sand or mud, usually deposited near the mouth of a bay or river. When a fast-moving river slows down to meet the ocean, it deposits tons of silt and mud that it carries. This bar forms a natural barrier, typically extending across the river or bay entrance, often at roughly right angles to the river current and the prevailing ocean swell and wind.

The West Coast of the United States is dotted with notoriously dangerous bars, including what is widely considered one of the most perilous in the world: the infamous Columbia River Bar, nicknamed The Graveyard of the Pacific. There, an area of shallow water extends for several miles around the mouth of the river and forms dangerous sand spits on both the north and south sides of the channel. The seas along a bar often are much larger and steeper than the ocean swell. The normal river current flowing out of the mouth, accelerated by an outgoing tide, collides with the incoming swell from the ocean over this shallow water, creating extremely steep breaking waves, even on days of relatively calm weather. Combine powerful current, large areas of dangerously shallow water and channels that may shift frequently and you have what could be a recipe for disaster. However, crossing a bar in a seaworthy vessel is not an insurmountable task.

Safe bar crossings are not out of the reach of any prudent mariner armed with good information. There are a few simple guidelines you can follow that will make a bar crossing safe and even enjoyable.

GOOD TIMING IS KEY

The most important consideration for crossing bars is timing. Bar conditions are strongly influenced by tides. When the normal river current combines with a strong ebb tide, the outbound current can become very powerful. Current velocities on the Columbia River Bar can exceed 8 knots on a large ebb tide. The current may be so strong that smaller or slower vessels simply can’t make headway against it, and it can quickly sweep a vessel into dangerously shallow water and breaking surf. But often, these dangerous conditions will subside dramatically when the tide turns.

Many accidents on bars are the direct result of mariners either being unaware of the tides or choosing to cross at the wrong time. The solution is relatively simple: Carry a tide book and know how to read it. Many chartplotters have built-in tide tables but, just as you should always carry paper charts, it’s wise to supplement electronic tide charts with printed versions. And, since most tide books are based on a select few locations, be sure you know what corrections must be applied to the tables to find the tides at the bar you intend to cross.

When is the best time to cross a bar? Actually, the easier question to answer is, when shouldn’t you cross a bar? In general, don’t cross a bar on an ebb tide. That’s when the seas will usually be the roughest and the strongest currents will occur. Generally, the safest time to cross is during the relatively brief slack-water period between flood (incoming) and ebb (outgoing) tides.

Some regions have diurnal tides (also known as daily tides), meaning that there is only one high and one low tide each day. Other areas, including the U.S. West Coast, have semidiurnal tides, with two highs and two lows each day. With semidiurnal tides, there are four slack times. Thus, there are four opportunities to cross the bar at slack water during each 24-hour period.

While in the process of planning your bar crossing, take some time to familiarize yourself with the tidal variations of the area. Compare the tides on the day you plan to cross the bar with the typical local tide swings. Will the tides be larger on the day you plan to cross? (That is, will there be a bigger variation between the high and the low?) In general, the larger the tide swing, the more likely rough bar conditions will develop.

With semidiurnal tides, one of the two daily tide cycles often will be considerably larger than the other. If possible, plan to cross on the smaller tide (the one with a smaller difference between the high and low tides). A lesser tide swing results in smaller ebb and flood currents and usually offers a longer period of minimal current. However, you should always avoid crossing an unfamiliar bar at night, so choosing a slack period between a larger tide swing during daylight is preferable to a slack tide in a smaller tide swing that occurs during darkness, unless you are familiar with the bar and it is well-marked with lighted navigation aids.

However, there are advantages to crossing on the low slack (at the end of the ebb), particularly on longer bars like the Columbia River, where there are several miles of potentially dangerous area and the crossing may take 30 minutes or more in a slower vessel. If you’re entering a bar from the ocean side, transiting at low slack gives you more time to cross: As the tide turns, it begins to flood, which may help by giving you a push on the way in. Also, in the event that you do run aground in shallow water, if you cross at low slack, the rising tide may help lift you off the bar.

River bars are also affected by runoff levels. In the spring, melting snow swells the rivers, which can increase the current during ebb tides and may decrease the current during flood tides. Familiarize yourself with the normal runoff levels for the river bar you plan to cross and check the runoff levels during your planned crossing time. If the levels are above average, expect more severe conditions. Bar conditions also are influenced by the sea state outside the bar, so if there is a large swell or significant wind waves in the ocean, the bar will most likely be rougher.

Finally, be patient. Many accidents on bars happen when the boat’s crew is tired, cold or seasick. Some crews get so anxious to get into a harbor that they think they can make it, even when the conditions are not safe. When in doubt, wait it out. Many times, we’ve slowed down or even made big loops outside a bar, waiting for a slack tide or better conditions.

CHECK BAR CONDITIONS

Even after you’ve studied the tides and planned a target time for your crossing, how do you know if conditions are safe? There are times when a bar isn’t safe to cross, even during slack current. While tides are one of the biggest influences on bar conditions, ocean swells, wind and river runoff levels also have a significant impact.

Fortunately, bar condition reports are relatively easy to come by. NOAA broadcasts brief bar condition forecasts for many of the major bars, often including the times of maximum ebb current, which should be avoided. Be sure to keep a list of the NOAA weather stations along your planned routes. The U.S. Coast Guard also is a good source of information on bar conditions. Don’t hesitate to call the USCG on VHF Channel 16 and request a report.

Some bars are “regulated” by the USCG, meaning the Coast Guard may close the bar to certain sizes or types of vessels. Typically, the first vessels to be affected by these restrictions are uninspected pleasure boats. Apart from these restrictions, the Coast Guard typically will not advise you as to whether you should cross a bar. At some locations, bar condition warning lights are installed to provide a visual indication of whether there is any kind of restriction on the bar. We haven’t found a single complete list of these locations, but the Coast Pilot and Coast Guard district websites are good places to check. Some larger bars with regular commercial traffic have a group of professional pilots who come aboard ships and advise the master of the vessel on navigating the bar. While these pilots primarily serve large commercial vessels, they offer a wealth of experience and information. The Columbia River Bar Pilots have a helpful website (columbiariverbarpilots.com) with links to a variety of weather and tide information.

If you are unsure of your skills or preparation for crossing a bar, consider hiring a captain who has specific knowledge of the bar you intend to cross.

WHERE TO CROSS

Generally, the safest place to cross a bar is in the main channel. However, the channel location may shift dramatically, especially on bars that are not actively maintained or dredged. Many bars have large rock or concrete jetties that are designed to help direct the current flowing out of the river into a confined area and thus minimize shifting of the channel. Heavily traveled bars like the Columbia River Bar are actively dredged to maintain the channel. These bar channels also are typically well-marked with buoys and range markers.

Other bars that are smaller may not be as well-marked, and some may not even have a defined channel. Even some relatively well-marked channels, such as the Tillamook Bay Bar about 50 miles south of the Columbia River, have been subject to large changes in the channel location. In general, it’s unwise to attempt to cross these unmaintained or unmarked bars without expert local knowledge and experience. You can learn from commercial fishermen in many of these ports, or by calling the local Coast Guard station in advance of your planned crossing.

If you do choose to cross a busy bar in the main channel, keep an extremely alert watch. Heavily traveled bars have nearly constant streams of commercial traffic, from freighters to fishing boats. They will be extremely limited in their ability to maneuver and will be restricted to the channel. Be sure to give them plenty of room by sticking close to the edge of the channel. You may even be able to stray slightly outside the channel to make room for commercial traffic, but it’s important to watch the chart and your depth sounder carefully, as areas outside the channel are subject to large variations in bottom contours.

OTHER BAR HAZARDS

The normal navigation problems associated with fog only get worse in the restricted channel of a bar. Traffic on the bar may be concentrated during the relatively short period of slack tide, so fog can be an even more significant problem when many vessels are navigating at the same time.

If you’re going to cross in fog, be adept at using your radar; you may want to supplement it with an AIS (Automatic Identification System). Be sure that you’re aware of where you are relative to the main channel at all times so you know where to go to avoid large commercial traffic that may have to pass you in tight quarters. If you are uncertain how to safely avoid a ship, hail the ship—typically on VHF Channel 13—well in advance of close quarters.

Dredges are another common hazard on larger bars. Be sure you know how to read the day marks and lights that the dredge displays. In general, the dredge will display two green lights or two diamond shapes in a vertical line to indicate the side that is safe to pass. Remember that dredges may also have floating pipes running to shore to carry the sand or mud dug from the bottom. These floating pipes are generally lit with orange or yellow lights, but they may be difficult to see at night because they are low and relatively dim. If you are in doubt, hail the dredge on VHF Channel 13.

PREPARATION IS KEY

Getting your boat ready for a bar crossing really is not that different from preparing for any rough-water voyage. Be sure you’ve performed all the required maintenance for your engine and other systems. Check that gear is stowed. Secure all hatches prior to reaching the bar. Many people choose to wear personal flotation devices during a bar crossing, for extra protection.

Make sure that you are familiar with handling your vessel in large following or head seas. Fortunately, in most bar crossings, the seas are generally directly on the bow or stern, so it’s unlikely you’ll have to deal with significant beam seas unless you attempt to turn around on the bar, which usually is not a good idea in less-than-ideal conditions.

The confined channel of a bar is not the appropriate setting for learning how to handle your vessel in steep seas. Gain that experience in a large, open body of water, where you have more room to correct for mistakes.

Crossing a bar safely requires careful planning and good seamanship, and there are great rewards for executing this successfully, including access to many beautiful, protected harbors. 

This article was originally published in the January 2023 issue.