My brother Daniel was as twitchy as a burglar in church. We were approaching Deception Pass on a recent cruise to the San Juan Islands in the Pacific Northwest. It was to be his first transit of the pass as captain and pilot. He was doing so in his 21-foot cuddy cabin sportfisherman, powered with a 140-hp Suzuki outboard. Top speed, maybe 35 knots.

I was a bit more at ease. Dan and I have been boating together since Jimmy Carter was president. We tend to move about a boat in a well-understood, often silent, choreographed ballet. Rarely does one of us do anything that surprises the other. I had also transited Deception Pass on many occasions in small, fast boats, and in not-so-small and slow trawlers. In all honesty, some encounters have not been my finest hour, but safe passage, I seem to find.

Deception Pass is created by the gap between the north end of Whidbey Island and the south end of Fidalgo Island. It is a spectacular place. High rock walls form the sides. The Deception Pass bridge was finished in July 1935 and rises some 180 feet over the water. This place is often a favorite of those with a camera in hand.

For those cruising from the southern waters of Puget Sound, the pass marks the unofficial arrival in the San Juan Islands after cruising north between Whidbey and Camano islands in Saratoga Passage. There are only two other routes from the southern sound to the San Juan Islands. One path takes the boater on the west side of Whidbey Island, which is exposed to the weather and seas of the Strait of Juan de Fuca. The other path calls for a boater to cruise north between Whidbey and Camano islands in Saratoga Passage, and then stop short of the pass to transit the Swinomish Channel. This route takes one through the pleasant town of La Conner, Washington, and exits at the north end of Fidalgo Island, then finally turns west toward the islands. This is a slower route, as the Swinomish Channel is largely a no-wake zone, and odd currents can further impede progress.

And so it is: Deception Pass is the oft-chosen route to the islands, notwithstanding the perils it presents.

The core of the pass is a rocky-sided, water-filled canyon. The water flowing through creates some of the fastest, strongest and potentially dangerous currents in Puget Sound, or for that matter, in the expansive waters of the Canadian Gulf Islands to the north.

Deception Pass is actually two passes. False Pass (also known as Canoe Pass) to the north is about 30 feet wide. Deception Pass to the south is about 150 feet wide at its navigable waters. The two passes are separated by a high rocky protrusion, upon which part of the Deception Pass bridge is affixed. Deception Pass runs between 4 and 37 fathoms.

Four times per day, the massive waters of the Strait of Juan de Fuca (to the west) and those of Saratoga Passage (to the east) surge through the narrow opening of Deception Pass. Two million cubic feet of water rush through the pass at peak flow per second. One cubic foot of seawater weighs about 64 pounds. So, at peak flow, more than 127 million pounds of seawater, or nearly 64,000 tons, flow through Deception Pass per second. To put those numbers in perspective, that is about eight times more water than the average flow of the Columbia River.

All that water crushes its way through the pass, creating maximum currents that can exceed 9 knots. The currents create massive whirlpools and eddies that can easily alter the course of heavy displacement vessels like a toddler being hit by an offensive lineman in the National Football League. Standing waves can reach 8 to 10 feet under maximum current, and when they’re coupled with an opposing wind and/or storm surge. Tugboats with a cargo tow, and low-powered sailboats, avoid the pass except at the hand of an expert captain and in the small window of slack tide.

The unique characteristics of Deception Pass are for us to enjoy as the result of gravity, the moon and the geography of Puget Sound. Even with a careful and informed reading of the tide chart and current table, transiting the pass can be a sweaty-palm proposition.

Deception Pass can ambush even an experienced captain. The waters approaching the pass from either the east or the west can be calm, seemingly devoid of any appreciable current. The reality in the core of the pass can simultaneously be quite disturbing. Many a time have I held back a good distance from the pass, waiting for the appropriate time to transit, only to see other boaters bull ahead and then circle back after the whirlpools spin their boat like a wine cork in a toilet. On other occasions, a large and powerful trawler will enter the pass at the wrong time. I watch knowing that its over-ground speed is dropping from 8 knots to 6, then from 6 knots to 3, then from 3 to zero. When the inevitable stalemate occurs between vessel and sea, the captain aborts the transit, turning broadside to the rushing water and imperiling any other vessel in the near vicinity.

So, all of this begs the question: When is it possible to safely transit Deception Pass?

The captain’s experience and boat-handling skills are factors to consider when answering that question. The type of vessel also matters. But before you start revving the engines, do these four things.

With these matters duly addressed, it is time to delve into the tide chart and current tables. Ideally, you want to transit the pass at slack water, or as close to it as possible, given the capabilities of your vessel.

Slack water (slack tide) should not, however, be confused with standing water (standing tide). Slack water is the state of a tidal current when its velocity is near zero. Standing water is the interval, albeit brief, at low or high water when there is no discernible change in the tide height.

Going through Deception Pass at a standing tide is not the same as a slack tide. On the former, you may encounter significant seas. On the latter, in theory, the current is zero.

If you spend much time boating in Puget Sound, then you probably are referencing a tide table that predicts the tides with a reference point of Seattle. For Deception Pass, it is necessary to reference the portion of the tide chart that calls out the adjustment to time and height of the tide for locations other than Seattle. When planning a passage through Deception Pass, making this adjustment is critical because it helps guide when you want to arrive.

Tidal currents are normally a benign event throughout much of Puget Sound, but the unique characteristics of Deception Pass make understanding the current a matter not to be ignored. Simply timing your passage through the pass when the flood tide turns to an ebb, or vice versa, is not good enough. Your tide chart will tell you when high or low tide is expected. It will not, however, tell you when slack tide is predicted; slack tide will not occur at Deception Pass until the water level is even on both sides of the pass. Depending on the day of the month, moon phase and other conditions, slack tide can be one to two hours after the high (or low) tide. Consult a current table to know the predicted slack tide.

In other words, if you are thinking that the current will be zero right when the flood tide turns to an ebb tide, that’s almost certainly not going to be the reality. To the contrary, you could find some of the strongest currents at the transition between flood and ebb tide.

Also be aware of the wind. When an ebb tide (water running to the west) meets with a wind from the west, large, standing waves are likely. The same is true when a flood tide (water running to the east) meets with an incoming wind from the east. These large, standing waves may not be apparent from a distance. The waves tend to have a short frequency, and are steep. They present a dangerous condition, particularly for small craft. A small vessel intending to go through the pass at, say, 20 knots suddenly encounters standing waves and may take green water over the bow. A swamping condition could ensue. Many captains in this situation will instinctively reduce power to take the boat off plane, while maintaining sufficient power to lift the bow. This sudden reduction in speed can affect following vessels, as they now face the prospect of running up on the stern of the leading boat. If any appreciable water has made its way on board, maneuverability will also be challenging.

Some boaters just follow another vessel through the pass, but I do not advise relying on this method. First, you are assuming that the lead vessel has a captain who knows what he’s doing. Second, vessels have different handling and seaworthiness characteristics. If I am at the helm of a trawler, then I may glean some guidance about the conditions by holding back and watching a vessel of similar size, displacement and power proceed first. If, however, I am at the helm of a 13-foot Boston Whaler, then watching that same trawler is not helpful in determining whether my vessel should proceed.

I also tend to treat the pass as an alternating, one-way road. Ideally, one vessel passes through at a time. The reality, however, is that you are likely to encounter captains who think otherwise. Sometimes, you will be in the danger zone when an oncoming vessel blasts through. Or, maybe your trawler is not going fast enough for the fisherman in a 20-foot aluminum boat, so he decides to overtake your vessel. Deception Pass is about 150 feet wide in the navigable waters, and it seems quite small when two trawlers meet in a head-on course, both being rousted about. Try to hold back and time your passage for when other vessels are not champing at the bit to get through. (But once you go, hold tight to a steady and clear course so others are not confused as to your intent.)

Once you have navigated Deception Pass, avoid holding up to admire your success and take a picture. Other vessels will be following, and stopping short can create a dangerous situation. Depending on the currents, reducing speed can also suck your vessel back toward the pass, which is not a good thing.

With solid seamanship skills and knowledge of tide and current, Deception Pass can be safely navigated. But keep in mind that the water never really comes to a stop. Be prepared for conditions different than what you anticipate, and have a backup option.

As for my brother Dan and his first transit as captain, with some guidance from his first mate and navigator, the experience was a success. Though I found it was difficult to discern whether even a small increase in confidence resulted.

Have a Good Plan

The moment when Deception Pass is in sight is not the time to be fumbling through the tide chart and tide tables. Have a plan not only for clearing the pass, but for immediately afterward as well. Know the course heading you intend to follow once you’re through.

Grab a 3-by-5 Index Card

These are a good investment at about $2 for several dozen. Here is the information to write on the index card: When you need to leave the moorage, when you need to arrive at the pass, what weather and sea conditions you expect to encounter, the earliest time you can transit the pass, the latest time you can transit the pass, and the plan if you cannot safely get through. Recording this information in good old-fashioned ink, while in the safety and comfort of your moorage, will provide confidence and minimize the potential for an unpleasant and dangerous situation.

Batten Down the Hatches

In any vessel going through the pass, some level of awkward and unusual movement will occur. Secure the items at the helm. (You don’t want to be distracted when your half-eaten maple bar flies to the sole.) Close and secure all hatches to prevent water intrusion. Docklines, fenders, coolers and such should be secured. Some years ago, a fellow boater told me about the time one of his docklines, still attached to a cleat, went overboard, fouled his propeller and caused a loss of power near the pass.

Assume your Guests Are Clueless

Well, maybe not completely clueless, but there is a good chance they may not appreciate the process of transiting Deception Pass. Inform them of what to expect before reaching the pass. At a minimum, guests should be seated and have a hand free for holding onto the boat. If you expect any assistance from a guest, make sure he or she is familiar with the task. And remind all guests that if the captain wants to hear your voice, he will ask you a question. Quiet helps with focus.