San Francisco bar conditions and currents

[MarkSF]

This year we have made a resolution to get out into the ocean outside the Golden Gate bridge more. Last year we did lots of sails around the bay, but only got out into the ocean once.

Given that the safest conditions beyond the bridge, across the bar, are at slack water and during a flood, my plan is to ride the ebb to the bridge, and get to the bridge around slack water / no current, allowing us to sail around for a few hours, and then ride the building flood back home.

Can anyone with experience of doing daysails beyond the bridge advise me if this is a good plan? Are my assumptions about the bar correct?

What would you consider the ideal time to get outside the bridge?

Obviously I'll be checking the weather forecast, including the sea state, before we go.

Thanks in advance!

[JPA Cate]

Mark, if you're concerned about it, make it a trip during neaps, the flow will be weaker. In Jim's Yankee 30, we sailed out to Pt. Bonita and back in a number of times, actually associated with MORA racing, and the Vallejo race.

In summer time, I'd look for him coming back from the Farallones race, singlehanded, with that spinnaker he built. A splendid sight.

Enjoy.

Ann

[donradcliffe]

Take a look the attached chart of the entrance. Basically, if you stay in the shipping channel, there is no bar. North of the channel is the four fathom bank, known locally as the potato patch. It also shallows to the south, but is closer to 5 fathoms there.

The ship channel is deep enough that it is safe under all conditions. The potato patch will get breaking waves in an ebb tide, and should be avoided if the forecast swell is over 8 ft or so. I have been hit by breakers a mile off Golden Gate Park with a predicted swell of 12 ft, so sometimes things can get a bit dicey if you cut the corner going south.

In the deeper areas, its not as much a concern about safety in ebb current, its more about the MSI (Motion Sickness Index). When I race out the gate, I look for rougher water as an indication of favorable ebb current, and head toward it. Of course, the currents are complex, particularly when they are changing, and you should carry a copy of the current charts.

The wind tends (not always) to peak under the bridge, and drop off when you get out in the ocean. The roughest water (except for the potato patch)is outside the bridge, but inside a line between Point Bonita and Seal Rocks.

[Celestialsailor]

Having sailed SF and Monterey Bay alot. I would just say do it in all condititions. The experience is good for your abilities. I went out on full ebb a few times and experienced being pushed towards one tower. Scary, but good experience. Another time at slack and the water seemed a little confused. When I went out the gate and turned left it was the end of a flood but was socked in with fog and used the radar to tip-toe out. Again, great experience.

[IRG]

I completely endorse all the below. I've been in the Potato Patch in fair weather on a 27 ton 57' boat and that wasn't fun (and once testing a liferaft!), but having been through the ship channel in both directions dozens of times and in every condition up to full gale, I've never had a problem with the channel EXCEPT bloody hell keep a watch on shipping traffic! There's often a lot in both directions. I entered on a surfing downwind run from Seattle once and when driven in between ships coming from left and right at dusk once I left a brown streak in my skids...

Originally Posted by donradcliffe

Take a look the attached chart of the entrance. Basically, if you stay in the shipping channel, there is no bar. North of the channel is the four fathom bank, known locally as the potato patch. It also shallows to the south, but is closer to 5 fathoms there.

The ship channel is deep enough that it is safe under all conditions. The potato patch will get breaking waves in an ebb tide, and should be avoided if the forecast swell is over 8 ft or so. I have been hit by breakers a mile off Golden Gate Park with a predicted swell of 12 ft, so sometimes things can get a bit dicey if you cut the corner going south.

In the deeper areas, its not as much a concern about safety in ebb current, its more about the MSI (Motion Sickness Index). When I race out the gate, I look for rougher water as an indication of favorable ebb current, and head toward it. Of course, the currents are complex, particularly when they are changing, and you should carry a copy of the current charts.

The wind tends (not always) to peak under the bridge, and drop off when you get out in the ocean. The roughest water (except for the potato patch)is outside the bridge, but inside a line between Point Bonita and Seal Rocks.

[gamayun]

I'm still not an expert at it, but lot's of good info from others about heading out, especially to go out on the last of the ebb so you get an assist. The only reason to head out on the slack is to minimize the chop you'll be facing from wind waves, particularly if it's really blowing. It's less of a problem when you stay in the deep channel. I also avoid the Potato Patch and Bonita Channel in all but the lightest of sea states (i.e., practically flat calm. Call me a chicken but YouTube will help dissuade you of this, too). Just watch where you are in relation to the channel when traffic needs to pass, and to Mile Rock - to stay on the outside of it. The Bonita side is more protected and you'll see small boats in the cove just outside the north tower waiting out the ebb. My advice is to be prepared for the return. Often it is dead down wind and with a big swell, so it can be a bit of bear to handle. You'll find how good your AP is. If it's really light wind, look at the water and other sails inside the bay, and be careful coming back under the bridge with a lot of sail up. It's like turning on the switch to a wind tunnel. But it's all very manageable. My first time surfing back from the Light Bucket and hitting 15 knots is etched forever on my mind as a highlight. In fact, just going out to the Light Bucket (about 6 miles outside) and back might be a good day trip.

[bruce v]

I have been on San Francisco bay (mostly in small fishing boats) in boats as small as 15' and grossly under powered. If, as you suggest, you are a fair weather sailor looking to enter and exit the bay. The best times to enter and exit are at slack tide. There are really no "tricky" spots other than those created by tidal movement. That being said, stay away from the bridge structures and toward the middle of the channel (lots of room here in both regards) and you will have no problems. I might also mention even being a fair weather sailor will not keep you from dealing with the occasional "blow" that are not uncommon to the bay. I have friends that will not go out on the waters there due to previous bad experiences (not with me although some of them tell me I am crazy for doing what I do in small boats there).

[Chuck Hawley]

Originally Posted by IRG

I completely endorse all the below. I've been in the Potato Patch in fair weather on a 27 ton 57' boat and that wasn't fun (and once testing a liferaft!), but having been through the ship channel in both directions dozens of times and in every condition up to full gale, I've never had a problem with the channel EXCEPT bloody hell keep a watch on shipping traffic! There's often a lot in both directions. I entered on a surfing downwind run from Seattle once and when driven in between ships coming from left and right at dusk once I left a brown streak in my skids...

Interestingly enough, I did a life raft test in the same area, on a 57' boat. What are the chances? I have fond memories of sailing under the GG Bridge in a 10' Tinker Dinghy with only a jib flying. That was awe inspiring! Ray, you were a good influence!

(Damn; would normally insert image of Tinker Dinghy, but cannot figure out UI of this forum. It's a good shot, too.)

And, back to the point, I think that you can experiment without a high degree of concern on virtually any day that doesn't have extreme currents or a high sea running. Stay in the channel(s), watch for shipping traffic (monitor Ch 14), keep your eyes open, and have fun.

Chuck

[Sailor647]

Originally Posted by donradcliffe

Basically, if you stay in the shipping channel, there is no bar.

The ship channel is deep enough that it is safe under all conditions.

Having motored our sailboat into and out of SF Bay in the shipping channels, I can attest that these statements are complete BULLSH*T!

This particular part of our journey (from Astoria, Oregon to Cabo San Lucas, Mexico, was one of the most challenging. It was actually rougher than our crossing of the Columbia River Bar.

Check the bar conditions before you go. And have a plan in case conditions change.

[Revenue Cutter]

While it (the MSI) was alluded in passing, if you're going to play around the potato patch, for the comfort of passengers and cleanliness of your boat, I'd bring an abundance of barg bags!

[Paul Elliott]

With a big ebb current and big seas coming in even the main channel can be challenging. The potato patch and south shoal / "channel" can be deadly.

But typically the main channel is fairly easy as long as you watch for shipping. When the currents are strong the washing machine near Pt. Bonita can really spin you around. There are useful counter-currents along the north and south edges of the channel, but there's no easy way to get under the bridge in strong current -- you just have to fight it. Avoid the south span of the bridge unless conditions are mild -- that's often a great surfing spot.

[EveningTide]

I like donradcliffs response and pretty much agree. I am a big chicken so I won't go out when a strong ebb is running. Also difficult if a strong flood is running. So I go out on slack but once went with a 2 knot ebb. That meant 3-4 foot chop but nothing worse. Naturally a big swell (>10 feet) can only make things worse. But I am always amazed when I go out to see many little boats out toward Bonita Point just sailing or motoring around like it was no big deal. I assume they have lots of local knowledge that I do not have.

I came in through Bonita Channel once in a 3 knot flood and 20 knots of wind. That was a very interesting ride but the cockpit never got flooded. Once out into the deep water past Bonita Point the water smoothed right out and we were swept quickly under the bridge.

I don't know what to think about the "south channel". It sure looks shallow to me (what channel?) and I have seen some very large and steep swells when crossing there on a 3 knot flood. But you see fishing boats out on south bar all the time. On my first visit to SF a fishing boat was capsized on south bar. There is even a spot there that is marked on the chart, "breakers".

[gamayun]

Heading to HMB once, I saw a big racing sailboat on its way to Santa Cruz hug the south shore so closely that it seemed they would be looking straight up at the cliffs. There is a "south channel" but all the books say don't use it. Many locals have knowledge about how to cut the corners, but then something like Low Speed Chase happens. If you're just going out for a fun day on the water, I wouldn't risk it.

[markpierce]

When sailboat racing in the 1960s for the Lightship Races, I always got seasick. Whole boats would disappear (except for their sails) between the waves.

[scotty c-m]

Mark also started this topic on SailNet.

San Francisco Bay bar and currents - SailNet Community

I posted this:

George and Stu have such good information. Thanks guys. If you look at the chart you see the channel and the north Potato Patch and south shallows.


I've experienced the roughest waters when the wind is coming in from the NW, and the Ebb is strong. The bigger the swell, the worse it gets. What do you guys think?

Look along the coast off Ocean Beach (the SF side). That's the South Channel. I think that place is a death trap. On a calm day it looks so simple. Go out the Gate and turn left. On a falling tide, if there is any swell you can sail into a shallow spot and the door in front, behind and outside closes into shallow water with breaking waves. I've done that channel a few times when the surf is really small, but I've given up on it, it's just not worth the chance to me anymore.

By the way, Mark, in my thinking, a two day trip to Half Moon Bay is a great adventure. Go down during the day when the weather is nice. Pay attention to the information about getting into Pillar Point Harbor. Yes, it is a bit tricky. Buddy boating with someone who has done it before makes it really easy. Enjoy Princton ( a very cool place), and motor back early the next morning before the wind comes up. Wow, what a trip.


Back to Cruisers Forum:

I do have one difference of opinion with DonR and Chuck. I know both of these guys and they are both VERY knowledgable and experienced, however, I stay out of the shipping channel. I usually stay to the South and run parallel a couple of miles to the south. Look at the chart. You can stay out of the channel on both the North and South side. There is a bit of shallows on the "red bouy side" (the south) near R6, but other than that, it's plenty deep. I stay on the outside of the channel because there can be a lot of shipping comming in and out.