{"id":3773,"date":"2025-06-14T13:45:01","date_gmt":"2025-06-14T20:45:01","guid":{"rendered":"\/wordpress\/?p=3773"},"modified":"2025-06-25T10:39:55","modified_gmt":"2025-06-25T17:39:55","slug":"sailing-with-karl-the-fog-in-the-sf-bay","status":"publish","type":"post","link":"https:\/\/www.tradewindssailing.com\/wordpress\/general\/sailing-with-karl-the-fog-in-the-sf-bay\/","title":{"rendered":"Sailing with Karl (the fog) in the SF Bay"},"content":{"rendered":"\n

by Tony Johnson<\/h3>\n\n\n\n

There is an old saying that \u201cif you can sail here\u201d\u2014meaning San Francisco Bay\u2014”you can sail anywhere.\u201d With the exception of coral reefs, we do feature most of the scary stuff you\u2019re likely to encounter at sea, including heavy winds, strong currents, shoals, lots of traffic from dinghies to container ships, lee shores in every direction, and fog. So it is a great preparation for the world beyond. San Francisco is famous for its fog. Of all our challenges, I dread fog the most.<\/p>\n\n\n\n

It can catch you unawares. I was once returning from Drake\u2019s Bay, before GPS and without radar. Right around Mile Rock, while I was near the shipping lane, the ceiling went from the top of the bridge towers right down to sea level in about one minute. All I had for navigation was a compass, and I knew that there were two container ships on their way out of the harbor, now completely invisible. I was, um, in their way. Think fast, skipper. I hailed Vessel Traffic Service on VHF 14 and told them of my situation. They have powerful radar capability and can see all vessels in the Bay, but I was nervous about this because I\u2019d never called them before and wasn\u2019t clear whether they would respond to recreational boaters. They assured me it was not only fine, but that even if it were a clear day, if I had doubts, they there for the purpose of helping mariners avoid collisions. I asked if they could tell me whether those ships were going to favor the north or south tower as they exited the Bay, and they said \u201cstand by.\u201d They called both captains and got back to me, saying that both would be closer to the south tower. I headed north by the compass, and sure enough, before long I saw them pass astern, right into my previous course.<\/p>\n\n\n\n

Another time, I was heading along the south coast of Spain on Maverick <\/em>with Terry Shrode on the way to Gibraltar, when fog blinded us within about five minutes. Our radar had been destroyed by lightning about a month earlier and we were to pick up spare parts in Gibraltar. We did have GPS, though, so we wouldn\u2019t be paying an unwanted visit to the shore, but this is a heavily trafficked shipping zone. We turned on the nav lights and headed a bit inshore in the attempt to avoid awkward encounters with ships. I placed myself on the bow with Terry on the helm. After an hour or so of boredom, I suddenly spotted a vague dark form to starboard which I took to be a ship, and yelled \u201cturn to port!\u201d Within about ten seconds, the entire view filled with a wall from horizon to horizon. It was the side of a container ship, and what I\u2019d spotted before was its rudder. We were about two or three boat lengths from contact.<\/p>\n\n\n\n

These are but two of a score or so of troubling fog encounters. Do not imagine that it\u2019ll never happen to you.<\/p>\n\n\n\n

Fog occurs when the temperature is at or below the dew point. Fog along our coast occurs because the cold water from the California Current cools the moist air just above, causing it to condense into fog. The prevailing westerly wind brings the fog into the Bay, and as it comes over the hills or spreads through the Golden Gate and leaves the \u201cslot,\u201d the air warms and mixes with the warmer air in the Bay. If the ambient temperature is cooler, particularly in morning or evening, the temperature will remain below the dew point and fog will extend farther inland.<\/p>\n\n\n\n

When you see it cascade over the hills in Sausalito, what you\u2019re seeing is the air warming as it comes down the hills into the protected Bay, rising enough in temperature to exceed the dewpoint while the flow of air continues. The rise in temperature is caused by adiabatic warming, and mixing with the warmer air in the Bay. Adiabatic warming results from the very slightly higher pressure and consequent higher temperatures at lower altitudes. In saturated air this is around 3\u00b0 per 1000 feet, but it only has to rise just above the dewpoint to dissipate.<\/p>\n\n\n\n

So how do you deal with it?<\/p>\n\n\n\n

    \n
  1. When fog occurs, turn on your navigation lights even if it is daytime and sound the appropriate signals (Colregs rule 20 and 35) depending whether you are under sail or power. Power driven vessels \u201cshall sound at intervals of not more than 2 minutes one prolonged blast.\u201d A sailing vessel shall \u201csound at intervals of not more than 2 minutes three blasts in succession, namely one prolonged followed by two short blasts.\u201d \u201cProlonged\u201d means 4-6 seconds. \u201cShort\u201d means one second. Blowing the sailing signal with the horn on your boat according to regs may require two minutes between signals to catch your breath. 4-6 seconds is a long time to blow. Don\u2019t ask me how I know.<\/li>\n\n\n\n
  2. Attend to your navigation. Radar and GPS are your friends. Even with the first, you absolutely need to keep a very close watch. You\u2019ll find this nerve-wracking. GPS will get you home, but what if you lack it? When conditions are ripe for fog, i.e., very cool temperatures, keep on top of your coastal piloting with dead reckoning and frequent fixes. Rember that current. Take the coastal navigation class and then practice while you\u2019re underway so when this occurs, navigation is not an unfamiliar experience. If the fog descends suddenly, you\u2019ll have a pretty good idea where you are in order to start plotting a safe compass course on your chart. I\u2019ve been in Potrero Reach when the fog was so thick I had to do this to get down the channel, as I couldn\u2019t see the next daymark.<\/li>\n<\/ol>\n\n\n\n

    At Tradewinds, our manual clearly states club rules: \u201cIn both winter and summer, fog on the Bay can descend very rapidly and create extremely dangerous sailing conditions. If visibility is poor when leaving the marina, stay very close to home. If you are across the Bay and see fog rolling in or visibility worsening, immediately take a compass bearing to safety and head there.\u201d<\/p>\n\n\n\n

    The prudent skipper takes nothing for granted. Know the procedure and if fog threatens, inform the crew of the situation and what you plan to do, which will help calm their nerves, and yours as well<\/p>\n\n\n\n

    If, despite reading this, you have neglected all of the above and find yourself too freaked to continue and are a deer in the headlights, remember that the folks at VHF 14 can see where you are. As a last resort, call the Coast Guard on 16. They\u2019ve rescued people for much worse seamanship than being lost in the fog.<\/p>\n\n\n\n

    \"\"<\/a><\/figure>\n","protected":false},"excerpt":{"rendered":"

    by Tony Johnson There is an old saying that \u201cif you can sail here\u201d\u2014meaning San Francisco Bay\u2014”you can sail anywhere.\u201d With the exception of coral reefs, we do feature most of the scary stuff you\u2019re likely to encounter at sea, … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"open","ping_status":"0","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[8,7,4,6],"tags":[],"class_list":["post-3773","post","type-post","status-publish","format-standard","hentry","category-chartering","category-club","category-general","category-skippers-tip"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/3773","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/comments?post=3773"}],"version-history":[{"count":1,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/3773\/revisions"}],"predecessor-version":[{"id":3775,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/posts\/3773\/revisions\/3775"}],"wp:attachment":[{"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/media?parent=3773"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/categories?post=3773"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tradewindssailing.com\/wordpress\/wp-json\/wp\/v2\/tags?post=3773"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}