San Francisco Potato Patch

I filmed this yesterday. It shows a trawler coming in safely from the ocean, however you can see a 15' - 20' sneaker wave breaking a few hundred yards behind it, where it had just been.


https://youtu.be/AZ9kru3KLDE

Every time (in the 1960s), I became seasick entering/exiting the potato patch during the lightship races. Whole boats, (but not their sails) disappeared among the waves.

What area is the potato patch?

jimdavi said:

What area is the potato patch?

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It's a shoal north of the San Francisco channel. The nickname came from several potato boats breaking up on it over the years. It's a ballsy shortcut into the Bay to say the least.

I remember, albeit vaguely, sailing my boat from Seattle to San Francisco because of a job transfer back in the early 1980's when we went from a sounding of hundreds of feet to about 30 feet. We couldn't figure out what was happening until we looked at the chart. WOW! None of us bothered to look at the chart until that happened. Luckily, the seas where calm and it was a none event.

After I lived and sailed in the bay area for awhile and heard the horror stories about the potato patch, I realized how lucky we where. I guess the anticipation of the long none stop cruise being almost over and the left turn into the bay almost in sight made us "stupid".

That's a great video of what can happen on the Potato Patch. I wonder if the guy who shot the video actually saw the boat head through there. The buoy to the left of the frame looks to me like the entrance/exit for Bonita Channel. If the boat had come down that channel it would have been between the buoy and the shore. Note that the wave breaks on the shoal and doesn't cross into the channel. I know many people do not trust the Bonita Channel - but this video shows a large wave dissipating before hitting the channel.

Richard

I shot the video and yes, the trawler had transited that area. I transit the bar frequently and decided to get the bird's eye view of it. I saw some large swells forming but not breaking. I decided to video some of it to show my cousin who is learning the ropes, to show him how the swells form in the area. When the trawler came around I started taping. It's five minutes of video and I just clipped it to show the breaker. If I had a video editor I'd show the trawler transiting the area, then take out the three minutes, then show the breaker. I'll post the other videos when I get some time. These are filmed from the Point Bonita light house.

Dear Carquinez Koot,

Would love to see your boat. I live in Benicia on a Sundowner tug. My email is blazingcontent@yahoo.com.

Great video!

R_p_ryan said:

I shot the video and yes, the trawler had transited that area. I transit the bar frequently and decided to get the bird's eye view of it. I saw some large swells forming but not breaking. I decided to video some of it to show my cousin who is learning the ropes, to show him how the swells form in the area. When the trawler came around I started taping. It's five minutes of video and I just clipped it to show the breaker. If I had a video editor I'd show the trawler transiting the area, then take out the three minutes, then show the breaker. I'll post the other videos when I get some time. These are filmed from the Point Bonita light house.

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If I'd read your original post more carefully I would have known you shot the video! Sounds like that trawler was foolish and lucky - the swell looks big enough that I would have stayed in the Bonita Channel. Was there an ebb running too?

Richard

I didn't check the tides. What I noticed though, is how totally unpredictable the waves were across the bar. There was nothing comparable happening in the main shipping channel. Makes somewhat of a case for taking it wide (offshore) when coming home from a fishing trip off Duxbury reef. However it adds at least a couple hours to the trip. I noticed that the steep or breaking waves on the bar dissipate as they get closer to shore, and I usually take that path when transiting the area. But what I saw that day made me think that I must hug the shore closer in order to avoid that type of sneaker. However, should the engine fail you'd be on rocks quickly. Being naturally afraid of the breakers on the rocks, one could easily be tricked into staying too far away from them.

i used to do some ocean racing out of the SF Bay and we would never cross the potato patch. That was on the short list of things not to be done under any circumstances, like going under the GG bridge south of the south tower. There was a video around a few years back of a Santana 22 that did attempted that route and it was not pretty. I'll look for it.

Edit: actually it is just photos https://www.latitude38.com/LectronicLat/2005/0405/Apr04/Apr4.html

the link to the complete set of 100+ photos not longer works but there are few in this link from latitude 38 magazine.

Nice video RP Ryan, sorry i did not say that before!!

Always wanted to visit the lighthouse pass it all the time.

I was in the Bonita Channel with my son and daughter on a "calm day" Son and I were on the flybridge and he said "Look at that Fu&*ing Wall of Water coming at us". Sure enough there was a random 20+ footer just rolling in across the Patch. Fortunately it broke after it passed under us.

In recounting the story to a bay area "Old Salt" he said "not sure I would ever refer to anything ever in the Potato Patch as a Rouge anything"

Pineapple Girl said:

... like going under the GG bridge south of the south tower. There was a video around a few years back of a Santana 22 that did attempted that route and it was not pretty. I'll look for it.

Edit: actually it is just photos https://www.latitude38.com/LectronicLat/2005/0405/Apr04/Apr4.html

...

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Wow - that's terrifying. I had a scary but much milder experience in my Cal 20 close to that spot. The wave didn't break but was steep enough to surf down, out of control , then broach and round-up.

I read somewhere that a rule of thumb for a beam-sea is a breaking wave with a height of 1/4 the boat's beam could capsize it, and there is no design that can withstand a wave height of 55% of the beam. I've been trying to find that stat but can't so maybe I made it up. So a 12' boat could theoretically be capsized by a 3 foot breaking wave if taken abeam. My guess is that type of boat is a poor design, but the point is that if you have breaking waves of even small height, then batten the hatches and get passengers off the flybridge.

Back when I did search and rescue on a 34' patrol boat we had a runabout try to pass us and it capsized. Our wake was breaking but it was less than 2 feet. The beam of the runabout was probably around 6 - 7 feet. It had an outboard, so the center of gravity would have been higher than an inboard. The water was glassy except for our wake which I guess didn't look significant for the runabout since it was approaching it from behind.

Howdy!

The Potato Patch and the San Francisco bar have fascinated me since I sailed out of the Golden Gate, cruising up to Point Reyes or in races such as out to the Farallon Islands.

Here is a link to a page which gives a very good description of the SF Bar along with tips for boaters who wish to enter.

The San Francisco Bar | CoastsideFishingClub.com

We took the Bonita Channel into SF Bay on our way down to San Diego from Victoria, BC, about six weeks ago. Swell was 2-3 feet at the time. Don't think I would've attempted it with anything more than that, based on some of the stories I had read and warnings I'd been given.

Two years ago I helped a guy take a 58' boat from Seattle to Stockton. We crossed the Potato Patch as we came into SF area. It was a bit choppy, but nothing real bad. That was on a fairly calm day and no, I don't recall what the tides were doing.