The Chas Lap

by Evan Morrison. 13 February 2014.

The “Chas Lap” is the longest, burliest standard training swim one can do in the Aquatic Park vicinity.

(By ”standard”, I mean: It is readily understood by a two- or three-word phrase in the SERC men’s and women’s saunas.

The Chas Lap touches, by definition, the western and eastern boundaries of the area in which it is acceptable for South End members to swim unescorted. There are bigger, burlier swims possible elsewhere in the Bay, but - and here’s the key - if you swim across the path of potential boat traffic, you must have an escort vessel. A Chas Lap can be done unescorted, and therefore requires far less planning.

Important Safety Caveats:

Click the map to enlarge:

san francisco aquatic park

To complete a Chas Lap, swim out from the South End beach to the Opening. Then turn left and swim along the outside of Muni Pier to Fort Mason. Not just Pier 1 of Fort Mason (as for an RTFM), but all the way to the end of Pier 3 - the entrance to Gashouse Cove Marina. Then, swim all the way back to the Opening and keep heading east along the Breakwater to the Creakers (entrance to Hyde Street Harbor). Then back to the Opening and into the Beach.

Or, in SERC shorthand: Beach -> Opening -> Gashouse -> Opening -> Creakers -> Opening -> Beach. Shortest straight-line distance is 1.95 miles. Let’s call it 2.

Chas D.


The Chas Lap is named after South Ender Chas D., who didn’t exactly “invent” this route, but started swimming it so often that people started calling it a “Chas Lap.”

The challenge of a Chas Lap is that you’re swimming against the current twice - not just once, as in a vanilla RTFM. And the second time is at the end of your swim, when you’re probably already exhausted.

Chas Laps are best done on a flood tide - so you swim the longer stretch of head current (Opening to Gashouse) first, and the shorter stretch of head current (Creakers to Opening) last. I do not recommend trying to get all the way back from Gashouse on a rising ebb. The currents can increase faster than you expect, and you can get tired faster than you expect. If you have to be rescued, you will bring shame upon Chas, the South End… really, just about everyone.

The cove between Muni Pier and Fort Mason. Not sure if it has a name.

The cove between Muni Pier and Fort Mason. Not sure if it has a name. Photo credit: D. Ho.

Varieties of Chas Laps

In order of difficulty:

The Creakers. SS Jeremiah O'Brien in background.

The Creakers. SS Jeremiah O'Brien in background.

One last thing, and I’ll try to put this gently:

Do not try this unless you know what you are doing.

If you’ve never swum in the Bay before, try going to the Flag and back. If you get tired of running head-first into triathletes along the buoy line, try swimming around the Cove once. Then twice. If you get comfortable in the Cove, try swimming against an ebb down to the Creakers. If you master that, maybe try a RTFM. If you are a fast enough swimmer to get to Fort Mason against a flood on most days, only then should you consider attempting a Chas Lap.

Don’t swim alone. Always check the tide books. Use common sense. Don’t be an idiot.

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Posted in: local Tags: San Francisco , SERC