Hanging precariously off the side of his 30ft sloop as it bashes upwind through the agitated seas approaching the Golden Gate Bridge, Mike Peterson is in his element. Which is strange, because the elements certainly seem to be doing everything they can to make Peterson feel entirely uncomfortable.
The wind howls through the pillars of the bridge at 25 knots, whipping at your face as you are drenched by the bitterly cold seaspray.
It is ebb tide in the bay, meaning the wind and tide are going in opposite directions, colliding tocreate a fierce chop on the surface of the water.
Peterson's yacht, Knarrmageddon - a play on the name of the fleet - pitches up and down in the waves.
"Isn't it incredible?" he enthuses.
A notoriously difficult sailing venue, San Francisco Bay has been described by Oracle Team USA skipper Jimmy Spithill as the ultimate battleground for this year's America's Cup match.
With its complex matrix of tides, wind and powerful currents, the bay is considered one of the toughest stretches of water to sail in and will test teams' ability to get the most out of their hi-tech AC72 racing machines.
Savage winds gusting over 25 knots are common on the bay, particularly later in the afternoon because of a confluence of sea breeze and the warm air coming out to greet it.
Then there are the tides.
Team New Zealand weather guru Roger "Clouds" Badham said few places on earth had such extreme tidal conditions. The current can move at around 3 to 4 knots in a slow tide, and up to 6 to 7 knots in the pinch points. Every six hours the water level in San Francisco Bay, which extends from San Jose in the south to North Bay, goes up or down about 1.5m.
"That's an enormous volume of water that has to come in and out the very narrow entrance, so it's a very, very strong flow of water," said Badham.
"All that makes for a pretty demanding sort of race.
"Just the sailing environment is tricky enough in itself, let alone thinking about where the opposition is on the racetrack."
In short, the bay is as choppy, unfriendly, unpredictable body of water as ever faced a yachtsman.
A San Francisco native, Peterson has been sailing on these inhospitable waters for 24 years.
He learned to sail on the America's Cup race course and reckons he's been on that stretch of water six days a week for most of his life. He is sure it is the coldest, wettest, most rugged place in the world to sail, but also the most beautiful.
"See, look at that," Peterson says, nodding towards the Golden Gate Bridge illuminated in an orange glow as the setting sun feathers through the pillars. "The view doesn't suck."
As he appreciates the picture postcard-worthy sunset, Peterson also remains seamlessly in tune with the environment. He points out different ripple patterns in the water, which indicate the changing current - of which there are plenty.
In the hour and a half it took to cross the bay from Peterson's berth at St Francis Yacht Club to the small, wealthy town of Tiburon beyond the Marin headlands, we crossed four tidelines.
Those tides converge right under the Golden Gate Bridge, creating a tumultuous sea state, which Peterson calls the "flushing toilet". The water surface also tells much about the direction and force of the wind. Dark patches on the water indicate where you can expect a puff of breeze, while the water flattens off where there is less breeze, which is what happens as we near the inlet near Tiburon.
After a white knuckle start to the sail, the breeze drops out and we are left drifting and, as much as he enjoys the adrenalin of being battered by the elements, that's entirely okay with Peterson as well.
He is a trained therapist ("the talking type"), but sailing is Peterson's therapy.
His passion was ignited when as a teenager he discovered his beloved Knarr sailboats - a beautiful 30ft wooden sloop originating from Norway - and has never bothered with any other class.
He bought Knarramegeddon with a mate in 2000, and has spent his summer holidays racing other Knarrs in Scandinavia - the only other part of the world outside of San Francisco where they are raced.
But a stroke about eight years ago kept him off the water for a while.
Peterson was having his fifth operation on a troublesome wrist ("I injured it picking up a box of heavy files, which just goes to show you how dangerous white-collar work is") when he had a stroke on the operating table.
The rehab was long and hard, and Peterson still has health problems from that day, "but the wrist is great!"
Ditching his career in finance, Peterson retrained as a therapist, and now works with athletes, mainly baseball players and golfers as well as actors and opera singers.
The more harrowing side of his job is counselling battle-scarred soldiers suffering post-traumatic stress and victims of trauma.
"So sailing is a good way to escape all of that."
Even when he's not able to sail on it, Peterson pays close attention to the bay. He pretty much knows all its quirks and characteristics, but every now and then it will throw up something that will surprise.
He has noticed that every year it is subtly changing. He's learned that man is responsible. Beyond the increasing temperature of the water caused by global warming, urban sprawl in the area has slowly but surely shifted and changed the wind patterns.
Peterson's desire to protect his stretch of water is why he has mixed feelings about the America's Cup.
He hates the zoo the bay becomes on race days; his mates at the St Francis Yacht Club, just down the road from the Golden Gate Yacht Club (or "Uncle Larry's supper club" as they call it), also find the continued disruption "a pain in the tuchus".
But he believes that for all the controversy the event has highlighted some of the good things happening in the local sailing community, not to mention the place he calls home.
Ask him who the real star of the show will be tomorrow when Oracle and Team New Zealand take to the water and Peterson will tell you: "San Francisco Bay".