Sailing out the Golden Gate

To many, the Golden Gate conjures up mental images of the Golden Gate Bridge. To most local seafaring types, the Golden Gate represents the channel or passage from just about a quarter-mile east of the Golden Gate Bridge all the way to an imaginary line drawn between point Bonita to the north and the corner of Lands End to the south. This “passage” is nearly 2.5 nautical miles in length.

Waters of the Golden Gate bounded by the Ruby red lines. the magenta lines represent the separation lanes for inbound and out bound traffic. The light blue represents more shallow waters and yellow land masses. The a Golden Gate Bridge is just to the west of the right most or East red line.

There is something magical, and a profound sense of accomplishment achieved, by sailors and passengers alike, in sailing under and past the Golden Gate Bridge. In fact, commercial fleets offering Bay tours, for a not insignificant fee, will steam through the bay, under the bridge, turn around, and take you back to your starting point. Sightseeing photo opportunities. I get it. I am likely guilty of taking at least one photograph every single time I cross the threshold passing under the bridge. New and inexperienced sailors, including many new boat owners not bound by sailing club rules and boundaries, oft venture out the gate unaware of the dangers that exist on the western side of the bridge. Look at the charts. It seems to be just an extension of the familiar and mostly manageable Bay. Well. It’s not! Let’s talk about why, the dangerous scenarios, a way to gain an understanding so that situations can be managed if unavoidable or unexpected, and my recommendations sailing the Gate based on what I’ve learned.

The gate is a narrow channel. The open ocean is to the west and the confines of the San Francisco Bay are to the east. It is bound by cliffs. The deepest part of the channel is well over 300 feet. Most of the depth is actually located in the gate west of the Bridge and yet part of this is also East of the bridge.

Underwater topography of the Gate.

The prevailing Northwesterly winds off the coast of northern California often back when they get close to land and become more Westerly. As this wind approaches the gate, it picks up in velocity due to the Bernoulli effect of having to pass through a narrow cliff-lined channel. This is perhaps enhanced by the wind blowing on shore during the summer months as a result of the rising heated air of the Central Valley drawing cold moist air into the Bay Area from the ocean. As a result, the wind in the gate can sometimes be unmanageable, and especially, if you are not prepared for it. For example, I have sailed traversing this region with wind offshore at 12 to 15 kn, wind in the gate at 37 to 40 kn, and wind in the bay at 20 kn. An unsuspecting sailor who is over canvassed, meaning with too much sail up not having reefed, might be in trouble and find it difficult to manage her vessel sailing upwind out the Gate or downwind in the Gate. Tacking upwind can be particularly difficult. The tacks are not always favorable and progress is slow unless your vessel sails well close to the wind. Further, to make any real progress, you will be required to tack back and forth across the shipping lanes. Don’t attempt to do so unless you are monitoring inbound and outbound traffic. If there is dense fog, turn on and utilize your Radar….. or just stay in the Bay. Sailing downwind in high winds can be fun but one risks exceeding hull speed and it’s attendant consequences. Accidental Jibes are possible. It becomes even more dangerous in certain conditions of the movement of the very water in which one is sailing.

So. What’s going on with the water? A lot! First, this is an area of extreme movements of water. The Sacramento River flow is believed to have been the major influence on formation of the channel. The flow of the Sacramento River is estimated to be 30,000 ft.³ per second! I can’t fathom that but it sounds like a lot of water flowing to the ocean. Next, in response to changes in the position of the earth relative to the moon and the sun, tidal flow is established where water comes in from the ocean and goes out from the bay in a cyclical fashion. There are approximately two high tides, as a result of influx of water (a flood), and two low tides, as a result of the efflux of water (an ebb), every 24 hours. This is an oversimplification and, if you plan to sail in tidal waters you should understand tides because the knowledge might actually spare your life. It has been estimated that 30% of the water in the Bay changes with each cycle of the tide. The estimated flow of water with an influx or efflux is 5,000,000 ft.³ per second. That’s about 150 times the flow of the Sacramento River! So, when the tide is flowing out along with the river, there is a greater current. When the tide is coming in, against the river current, the resulting current is probably somewhat lessened as it is opposed. Depending on the phase of the moon, the tidal currents in the Gate can range from 1 kn to over 4 kn. In most sailboats, with an average speed of 5 to 7 kn, it’s easy to see that the directional flow of water can significantly facilitate or impede one’s progress. If there was no wind, and you were motoring, and if the water is flat, you’re best course of action is to take into consideration the direction of planned travel and current flow. For example, if you have been picnicking in the ocean, and are returning to the bay motoring at 6 kn, and the current is flowing outward, at 4 kn, you’re only going to make 2 NM progress in an hour. It’s not only a waste of time……. it’s a waste of energy. One thing you can do to improve your situation is to recognize that the current runs faster in the deeper parts of the gate channel. Thus, it is best to stay to one side or the other, depending on directional flow of traffic, when the ebb or the flood currents are at or near their peaks.

Simple enough? Not really! There are other factors related to water movement that the adventuresome sailor must consider when planning to go out the Gate. These relate to the prevailing swell and the effect of wind on the water. The swell is the movement of water, usually inbound, that results from storms out to sea. The swell can be very small or large depending on the magnitude and distance from shore of a particular storm resulting in the swells. Sometimes there are two swells off of our coast. The predominant one seems to come from about 275°T and the lesser one from about 220 to 240°T. The swells pass through the gate and into the bay. They often seem to become smaller as one progresses from the ocean into the Gate. They can be, however, somewhat large in the Gate and into the bay. Sometimes they are reflected by the surrounding cliffs making matters a little bit more complicated and creating a confused sea. I have seen swells as high as 12 feet off of our coast then dissipating and rolling through the gate at about 5 to 7 feet. They have been large enough that 900 ft tankers seem to almost disappear in the trough of a distant swell when viewed from a sailboat in a trough. You’d better know how to sail these swells, or motor through them, both upwind and downwind if you’re going to venture through the Gate when there is a significant swell. That’s not all there is to it, though, as you might have imagined by now! The Period or time between the swells is also important. The closer they are together the more likely one is going to get in trouble if he makes a mistake in sailing these rolling waves. Do your homework! But wait…..let’s make it even more complex! If the wind is really blowing, you are going to also have to contend with wind waves that can vary in height from 1 feet to 7 feet, in my experience but they can be higher, depending on the wind strength duration and fetch, or distance the wind has affected the water. Don’t forget, the two swells that I have mentioned sometimes combine to make a larger swell. Further, the wind waves sometimes combine to make a larger waves. The wind waves and the swells combine, too. One can end up in a situation where there are some huge unexpected waves as a result of all of these combinations. Of course, sometimes they cancel out. But you should always expect larger waves than predicted.

An approximately 900 ft oil tanker re-emerges from the trough of a 12 foot swell just outside the Gate.
A reasonable guide to decision-making regarding whether to sail based on predicted wave height versus wave period. I’ve sailed enough to highly advise you believe and follow these guidelines.

Do you believe you have it all figured out? Hold on another minute! Now you have to put it all together. The most important and critical thing to recognize is that the swell, wind waves, wind speeds, direction of tidal current, proximity to peak flow, and speed of the current must be combined and dealt with in your mind when venturing through the gate. One has to learn to quickly assess a situation, make decisions, and adapt the vessel to the prevailing conditions.

Far and away, the most dangerous situation, even though there are several, is in attempting to go out the Gate during an ebb tide of significant magnitude of current flow in the presence of a significant wind from any direction close to west. Whenever the current flows out against the wind large “standing waves” may develop as a result of the opposing actions of the current and the wind. Throw in a swell and wind waves, then some high wind, and it can become, frankly, treacherous in the Gate. The waves do break. They can toss a sailboat if one does not sail the waves properly. Sailing upwind can be next to impossible, and especially, in winds exceeding 30 kn. Sailing back downwind in this situation is plain dangerous. A wave can crash over the stern. The vessel can yaw by 45 degrees and an accidental jibe is possible if one does not maintain control and sail the waves properly. The boat can be knocked down if a significant wave is taken on the beam. All of these disastrous situations are more or less of a potential problem depending on the inherent seaworthiness of the vessel you are sailing. Don’t event think of trying to take a Bay cruising sailboat, or a vessel under 35 feet unless it is designed as a blue water cruising vessel, out the Gate and especially if the conditions are the least bit suggestive of trouble.

I have seen several vessels obviously “in over their heads” in the Gate. They’re easy to spot. Don’t be one of those skippers! Read and understand the circumstances affecting the movement of the water and air and make sound decisions whether to go or not….regardless of which body of water that you may be sailing on. Ensure that your vessel is up to the conditions on hand. Try to go out the Gate at slack tide and plan your return time at slack or with a favorable tidal flow. Read about heavy weather sailing and boat handling in swells, wind waves, etc. Learn what to do when presented with different situations. Learn how and when to safely execute your tacks and jibes. Most importantly, set yourself up for an opportunity to practice.

At some point, you will be caught in a situation, such as going out the Gate, or some unfamiliar tidal body, on an ebb when the wind is coming in. You might be crossing the Gulf Stream, off the East Coast, flowing northward when the wind is blowing from the north. You may be sailing along with an ocean current somewhere off the coast of South Africa with the wind coming directly opposite the current and face the same situation, but much much worse. So, how does one prepare? Practice!

Go out the gate with an ebb against a strong wind! I’ve done it plenty of times to gain experience. Most of the time, it’s relatively straightforward. Simple. Not difficult at all. Three or four times it has been a challenge, due to a combination of factors leading to a joyous ride, and, on one occasion, it was nearly a harrowing experience. I was able to gain confidence in Skiron and also my abilities as they were refined on each occasion. Be careful. Don’t be foolish. Yet, get some experience. Go out when the conditions are not fully developed. Graduate to a higher degree of difficulty as you learn to understand the factors affecting conditions and as you attain skills. It’s difficult to make this recommendation. I believe, however, an important part of sailing is preparedness based on experience.

I didn’t address the situation of coming back in through the Gate with a swell, high wind, wind waves, and a flood. It’s not nearly as treacherous. You will encounter some choppy water. And you will run fast so be careful with your downwind tactics. Don’t jibe by accident!

Point Bonita. It looks like a crocodile…..and is much more dangerous!

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