Sailing Adventures

Crossing the Bar

If you are planning to transit the U.S. Pacific Coast, the following information about crossing river bars may be of interest to you. Because the Columbia River bar is the most challenging of all the West Coast bars, I will give it extra attention.
Why cross the Columbia bar at all? Astoria is a wonderful historic harbor town with a great marina, excellent chandlery, and lots of good restaurants and places to see. Portland, Oregon is just a day sail up the river. The Columbia Gorge is a stunning cruise, with the Bonneville Dam, Cascade Locks, and Hood River to explore. The Columbia and Snake Rivers are navigable all the way to Lewiston, Idaho 425 NM inland with eight dams to pass through.

The Columbia Bar
The Columbia Bar, referred to as The Graveyard of Ships, is one of the most dangerous in the world, according to Lloyds of London. During winter storms, waves can exceed 40 feet in height. Over 2000 ships have been lost crossing the bar in the last 150 years.
Despite the dangers, approximately 3,600 large vessels cross the bar every year guided by a Columbia River Bar Pilot. These ships haul about 40 million tons of goods valued at $23 billion between the Pacific Northwest and the rest of the world. Countless smaller craft cross each year without the benefit of a pilot, including commercial and recreational fishermen, sailboats, and trawlers.

Crossing the Columbia Bar
Most of the river bars of the West Coast of the U.S. consist of one or two stone jetties that extend into the ocean past the line of breakers at such an angle that they provide smoother water behind them. The danger zone on a typical bar is 100 yards or less. Crossing most bars involves carefully timing two or three swells before passing the end of the jetty and entering the protected harbor.
The Columbia bar is much longer. The danger zone can extend up to a mile, especially when the winds or waves are out of the southwest. The north jetty extends one half mile southwest from the northern headland, Cape Disappointment. The south jetty extends nearly three miles west from Clatsop Spit, a low lying sand spit separating the river channel from the ocean for eight miles.
You will feel the effects of the river for as much as fifteen miles off shore. When passing by the mouth of the Columbia with no intention of entering you should stay seaward of the ODAS weather buoy #46029 to avoid the potato patch that sometimes extends well out to sea.

Tidal Influences 
Changes in tides and currents are caused by the gravitational pull of the sun and moon. Imagine if you will a globe covered with water. The depth of the water would logically be about the same everywhere. Now add a sun to the equation. The gravitational pull of the sun will pull the fluid water toward it, making the shape of the water surface more egg shaped pointed at the sun. Next, add a moon. Though smaller, it is closer so its gravitational pull has a greater influence. Now you have two egg shapes overlaid over each other, one pointing at the sun and a larger one pointing at the moon.
When the sun and moon are more or less aligned, either in the same direction around the dark of the moon or opposite each other near the time of the full moon, the gravitational pull on the ocean waters can be doubled. During these times the tides are much higher. These are called the "Spring Tides". When the moon is half full, the sun and moon aren't in alignment and their gravitational pulls cancel each other out to some extent. The result, called the "Neap Tides", is lesser tides and currents.
There are important differences between tidal levels and tidal currents. Each has its place in your planning and it is important to be aware of the state of the tides when planning a voyage, especially in tidal zones such as river bars. Good navigating systems such as Rosepoint Coastal Explorer or Nobeltec provide tide and current information in graphical displays for most locations along the Coast, aiding your planning.

Tidal Levels
The tide level determines how deep the water will be at various stages of the tide. Tide levels are easily observed if you tie to a dock next to a piling. At high tide the piling will appear to be shorter, cleaner, and drier than at low tide, when the lower portions of the piling may well be covered with barnacles and damp seaweed. It is obvious that the depth of the water is changing on about six hour increments.
This is important if you plan to anchor in an area with large tides. For example, if you anchor a vessel with a 5' draft in 10' of water at high tide in an area where the tidal swings vary by 6', you may awake to find your keel stuck in the mud at low tide.
However, during ocean travel when vessels rarely travel in less than many fathoms, an extra 5-20' of depth caused by the tidal influence has little impact on your vessel. At some river bars where there is shoaling at the end of the jetty this might be a concern but, as a practical matter, if you are close enough to the jetty to worry about shoaling, you probably have bigger worries than the state of the tide.

Tidal Currents
As a mariner it is important to pay close attention to tidal current levels any time you are in an area affected by tidal flows. Considering that the tidal level is changing up and down every six hours, a lot of water flows in and out of a bay or estuary to make these changes. At times the flow can be substantial.
Current levels describe how fast the water is flowing in or out of the mouth of a bay or river estuary or between islands and points of land within a tidal zone. This has an immediate effect upon your progress through the water. An extreme example is at Deception Pass, between Fidalgoand Whidbey Islands in the Puget Sound. The bulk of the body of water behind these long islands ebbs and fills through this narrow pass. At full flood or ebb, the flow resembles a white water river with large standing waves and overfalls. The Pass is extremely dangerous for vessels shooting through on the current and is often impassable even to powerful speedboats attempting to run up current.
Consider if the current at a river bar is running as high as 5-6 knots. If your boat only makes 7 knots, you can sit in almost the same spot for a long time in rough and unpredictable conditions. Always plan your trip to depart and arrive at the river bars on favorable tidal currents.
What are favorable currents? When the tidal waters are flooding into a bay or estuary there may be more tidal water entering the channel than is exiting with the river flow. The opposing flows partially cancel each other out making for flatter conditions.
When the tide is ebbing, the full river current flowing out is increased by the outgoing tidal flow. This makes heavier currents to contend with. Worse yet, if this increased volume meets a strong onshore wind, as is typical during the day for much of the year in the Pacific Northwest, the opposing forces of wind and current can create large, square waves. This is uncomfortable at best and can be extremely dangerous at worst. Hitting a large square waves at a slight angle can spin a boat rapidly into a broach.

Secrets to Crossing any Bar
The safest time to cross any bar is typically after the full flood but an hour or two before the slack. The currents will be subsiding but you will have a time buffer before the beginning of the ebb tide in case you arrive later than planned. Ideally you should plan your transit to leave harbor on one favorable tide and arrive at your next port on another favorable tide.
Unfortunately, due to the distances involved, the timing doesn't work. You must choose which bar is most important to get the timing right on. It is generally easier to cross a bar outbound than inbound. Presumably you've already crossed it once to get into the harbor so you will be more familiar with the hazards. Secondly you will be better rested at the beginning of a passage than at the end when your judgment may be impaired by lack of sleep.
It is easier to see the wave sets from the inland side. And finally the waters are calmer inside the bar so you can slow down or stop to observe the conditions prior to making your move. Remember that waves come in sets. Watch for a big set to pass through then make your crossing on a smaller one.
As a rule you will plan your passage to arrive at or near a favorable tide and time your departure to achieve that. This may require burning extra fuel to make a bar crossing or slowing down to arrive at the right time.

Coast Guard Assistance
The United States Coast Guard monitors VHF channel 16 and conducts business on channel 22. Once an hour most local Coast Guard stations will make an announcement on VHF Channel 16 inviting you to switch your radio to Channel 22 for a description of the current bar conditions. Or you can call the local station on VHF Channel 16 for an update before entering or leaving port. If you ask for assistance they may send a patrol boat to stand by as you make your crossing.
The Coast Guard is hesitant to advise you on when or whether to cross a bar and will typically respond that "as Captain of your vessel you are responsible for the safety of your boat and crew". However if you call them on a cell phone instead of over the open air waves they are often more forthcoming with advice regarding likely prospects.
The Coast Guard has a series of warnings by which they regulate the bars. The lowest warning is a Small Craft Advisory. This means the winds are predicted to approach 21-38 knots within the next twelve hours. At times they will fly a red triangular flag to indicate that an advisory is in place. Small craft are considered to be vessels less than 33' in length.
The second level is a Small Craft Warning or Gale Warning for winds of 39-54 knots. Two red triangular flags, one above the other, indicate a gale warning is in place.
Storm warnings for winds of 55-73 knots are indicated with a red rectangular flag with a black rectangle in the center.
Sometimes wind or wave conditions make the bar unsafe to cross, usually due to breaking waves across the mouth. The Coast Guard will close the bar, first to small vessels such as 26' and under, then to larger vessels perhaps 40' and under, and finally to all traffic. Sometimes the closure will last for a few hours until a change in the tide creates a change in conditions. In this case you may choose to sail offshore for a couple of hours then make your way back in time for the slack. Other times such as during a winter storm the bar may be closed for days. At these times your only option may be to continue to another port.
Do not attempt to cross a closed bar or you may face a heavy penalty either in money or in the loss of your vessel and/or your life. This is especially true at the Columbia bar one of the most dangerous in the world!

Crossing a bar can be intimidating. However, once you familiarize yourself with the process, it becomes easier and less stressful.

Safe sailing!

Douglas Cochrane
S/V Simplicity, Nonsuch 30
Formerly M/V Orion, Nordhavn 57-25