Sailing to a specific time schedule can be dangerous. Trying to “get there” at a specific time, or wanting to trim 20 minutes off your sailing ETA may create a situation where you put yourself at risk.
While returning from Drakes Bay during a recent Advanced Coastal Cruising class I made the decision to go through Bonita Channel to get home. We had been out for three days, and I was really looking forward to getting home as quickly as possible. Bonita Channel is a one third mile wide alternative to the main ship channel as a means of getting through the San Francisco Bar. It runs between Potato Patch (Fourfathom Bank) and the shoreline of Point Bonita. During mild conditions it cuts quite a bit of time off the trip into the bay from the north.
The decision to use Bonita Channel was based on conditions as we approached. We had 3 to 4 foot swells with a very long period. In other words, it was quite calm, so we made the turn towards the channel. The approach to the channel is like a continuously narrowing funnel of deeper water between two areas of shallower water. During the 20 minutes following our turn into the approach, I watched the swells build from 3 and 4 feet up to 7 and 8 feet. The shallow water to the sides was causing the swell to hump up making me a bit nervous, so 20 minutes into the approach I changed my mind and back tracked to use the main ship channel. Of course, during the next hour I questioned my decision, thinking to myself that going through Bonita Channel would have cut 3 miles off my trip and would have been perfectly safe.
When we reached the point where Bonita Channel joins the main ship channel, I checked out the conditions we would have been greeted by had we gone that way. At a distance of 1/2 to 1 mile, it’s hard to judge height, however, I would estimate there were 3 foot breakers rolling across the channel for most of it’s length. Being hit on the beam by 3 foot breaking waves for a mile isn’t my idea of a fun time. In this case, the correct decision was made!
Sailing on San Francisco Bay involves a constant series of choices like the one above. Choices like: I’m not going to do a complete checkout of the boat because I’m running late and there is never a problem; or, the shortest route takes me through those small kids on dinghies and I don’t really want to take the time to go around; or, following the west side of the channel is faster, but the east side keeps me clear of the tug harbor and the marina exit; or, I think I can make it in front of that tug pulling a barge and I’ll be late if I give way and go behind. Don’t fall into these traps. Be willing to make the best decision based on circumstances and be willing to revise choices mid sail as changing circumstances require.