Living near the Golden Gate bar -- one of the most dangerous pieces of water in the world -- and being a Coast Guard volunteer, as well as a local charter skipper, I am privy to the details of the deaths at sea which occur every year within sight of San Francisco. Most of these deaths happen because experienced sailors visiting the area do not take the time to carefully study the local conditions before trying to sail here.

But the same is true on every coastline. Peculiar local conditions can sneak up on even the most experienced sailors. Here on the Northern Californian coast, this lack of local knowledge causes the capsizing of as many as three yachts each year in the steep seas that mount every afternoon just off the mouth of the Golden Gate.

The crews of these stricken vessels are often very experienced world cruising sailors. Yet, unaware of the local phenomena, they confidently believe they will have an easy passage.

A couple of years ago, a 20-foot sailboat operated by a skipper unfamiliar with the Northern California coast was making a passage from Half Moon Bay into the Golden Gate. Leaving Pillar Point Harbor in the morning, the gentle seas along the Montara coast that morning gave no warning of what lay ahead.

Six hours into the cruise, and half an hour from the Golden Gate, the boat got into the rollers off San Francisco's Ocean Beach, just south of Point Lobos. The rollers capsized their boat at 2:23 p.m. Bystanders on the beach reached the Coast Guard by 2:40 p.m., and they immediately dispatched two 47-foot motor lifeboats from Station Golden Gate six miles away. A Coast Guard helicopter went up and the San Francisco Fire Department launched its surf rescue team within five minutes.

Two survivors were rescued by fire department divers and taken to UCSF Medical Center, where they were treated for hypothermia. However, a third man, who was only 22 years old, was never found. Several witnesses said that they had seen the vessel roll over in the surf and sink beneath the waves. According to Coast Guard reports, the missing man was somehow tethered to the boat.

All this was avoidable. Three hours earlier, or three hours later would not have been during the ebb, and there would only have been gentle waves. The high winds and steep seas that capsized the boat were predictable. It was a fair weather sunny day. Due to the warming of the afternoon sun, by 2 p.m. every afternoon, winds are blowing onshore at 18 to 20 knots everywhere on the Bar outside the Golden Gate. When the tide also happens to be running out during the ebb, it creates steep seas on the bar. Inside the Golden gate this is what creates the wonderful 25 to 30 knots in "the slot" which makes good sailing winds off the St Francis YC so predictable.

These were safety conscious boaters with proper lifejackets and harnesses tethering them to the boat. They had left San Diego a couple of weeks before and were making their way up the Pacific Coast to British Columbia. So they already had 450 miles of Pacific Coast sailing behind them, which means that they were no longer novice sailors even if they had been at the start. Two weeks at sea on a coastwise passage is more hands on experience than most pleasure sailors get in five years of weekend sailing. Yet, they unknowingly arrived in the hazardous area at exactly the time of maximum ebb current when the normal local conditions are always hazardous.

One of my mentors and a seasoned veteran, Captain John E. Kelly of West Seattle's Sea Scout Ship Yankee Clipper, had this to say about the secrets of successful passage making:

"When you have to make a passage off a strange coast read all you can about it, but don't forget as you make each port, to visit with all the other skippers, especially aboard the local fishing boats. Pick the brains of those who have recently been where you are heading, to perfect your local knowledge before you set out."

Capt. Alan Hugenot is a naval architect and marine surveyor based in San Francisco, where he operates an 81-foot motor yacht converted from a Navy patrol boat. His column appears here weekly.