{"id":1981,"date":"2018-08-14T09:42:28","date_gmt":"2018-08-14T16:42:28","guid":{"rendered":"http:\/\/tradewindssailing.com\/wordpress\/?p=1981"},"modified":"2018-08-14T09:42:28","modified_gmt":"2018-08-14T16:42:28","slug":"exiting-chrysopylae-the-golden-gate","status":"publish","type":"post","link":"https:\/\/www.tradewindssailing.com\/wordpress\/general\/exiting-chrysopylae-the-golden-gate\/","title":{"rendered":"Exiting Chrysopylae … “The Golden Gate”"},"content":{"rendered":"

Also known as … is it safe to head out the gate?<\/strong><\/p>\n

For over two hundred years, the Golden Gate hid its existence from the Europeans transiting and exploring the coast of California by boat.\u00a0 First “missed” by Juan Rodriguez Cabrillo in November 1542, the Golden Gate was discovered accidentally in November of 1769 by a land expedition working it’s way north along the San Francisco peninsula in an attempt to reach Point Reyes.\u00a0 Needless to say, the one to two mile wide expanse of water moving into and out of what would become known as San Francisco Bay halted the successful completion of the mission.<\/p>\n

In 1846, John C Freemont coined the name we now know.\u00a0 In his memoirs he wrote “To this Gate I gave the name of ‘Chrysopylae’, or ‘Golden Gate’; for the same reasons that the harbor of\u00a0Byzantium\u00a0was called Chrysoceras, or\u00a0Golden Horn.”<\/em>\u00a0 Freemont saw this as a “golden gate to trade with the orient.”\u00a0 So, the name has nothing to do with the discovery of gold in California, or the famous bridge that spans its eastern end.<\/p>\n

However, this is a sailing tip, not a history lesson or a linguistic exploration of the Greek word Chrysopylae, translated “Golden Gate.”\u00a0 Instead, we will be looking at guidelines to follow while determining if and when it is safe to transit the Golden Gate, pass outside the line of demarcation, cross the San Francisco Bar, and sail the waters of the Gulf of the Farallons.\u00a0 It is important to remember, these are guidelines which do not take into consideration your level of skill, the skill of your crew, or the seaworthiness of your vessel, all things that MUST be taken into consideration when sailing anywhere, anytime.<\/p>\n

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Gulf of the Farallones – Chart 19645<\/p><\/div>\n

Currents<\/strong><\/h2>\n

Water from the Pacific Ocean flows into (floods) and out of (ebbs) on a cycle that repeats itself twice each day.\u00a0 In between each flood and ebb is a transition period referred to as slack water where there is relatively little movement of water.\u00a0 Step one of deciding if it is safe to sail outside the gate is determining the best time to transit the gate.\u00a0 To the untrained, the best time would seem to be during the ebb, so that you can ride the current out and get there quicker.\u00a0 Unfortunately, that is actually the worst time to go.<\/p>\n

One of the first things someone notices when approaching the bridge from the bay is that the water begins to “feel” different.\u00a0 Less and less are you experiencing the wind driven waves and chop of the bay, and more and more you beginning to ride the swell coming in from the Pacific Ocean.\u00a0 During an ebb, water moving out of the bay at velocities that can exceed 6 knots runs into swell coming into the bay resulting in increases in size and frequency.\u00a0 \u00a0A fact that is true of every river bar in the world.\u00a0 Throw in San Francisco’s famous 25 knot winds and things get really interesting.<\/p>\n

\"\"<\/a>Instead, I prefer transiting the gate, in either direction, on the slack before the flood.\u00a0 Second choice would be slack before the ebb, but get there a bit early.\u00a0 You don’t want to get caught in transit during the ebb.\u00a0 The flood would be next (makes for a slow trip out or a quick trip in) with the ebb being last.\u00a0 If you must exit on an ebb, make it early in the morning before those breezes pick up.\u00a0 Better yet, wait a few hours and go out on the next slack.\u00a0 In the example shown, I would most likely leave Marina Bay about 10:30 to arrive at the bridge between 12:00 and 12:30.<\/p>\n

Forecasts of the currents through the gate are found in tide books and online.
\nhttp:\/\/tbone.biol.sc.edu\/tide\/tideshow.cgi?site=San+Francisco+Bay+Entrance+(Golden+Gate),+California+Current<\/a><\/p>\n

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San Francisco Bar and Main Ship Channel<\/p><\/div>\n

Coast Pilot 7, Chapter 7, contains a wealth of information about transiting the gate and crossing the bar.\u00a0 The Coast Pilot Index if found at
\nhttps:\/\/nauticalcharts.noaa.gov\/publications\/coast-pilot\/index.html<\/a>
\nClick on California to bring up Coast Pilot 7.\u00a0 Unless otherwise indicated, all references to the Coast Pilot are from Coast Pilot 7, Chapter 7 (CP 7:7).<\/p>\n

CP 7:7 Item 43, describes the San Francisco Bar as:<\/p>\n

“a semicircular shoal with depths less than 36 feet, is formed by silt deposits carried to the ocean by the Sacramento and San Joaquin River systems. The bar extends from 3 miles south of Point Lobos to within 0.5 mile of Point Bonita off the southern coast of Marin Peninsula; the extreme outer part is about 5 miles west-southwest of San Francisco Bay entrance.\u00a0Potatopatch Shoal\u00a0the north part of the bar on Fourfathom Bank\u00a0has depths from 24 to 28 feet.”<\/p>\n

The San Francisco Bar is the light blue areas of shallow water shown in the excerpt from the Entrance to San Francisco Bay chart above.\u00a0 It is approximately 8 miles from the bridge to the last buoy through the Main Ship Channel (G “1” Iso G 6s BELL).\u00a0 Expect it to take 2 hours (plus or minus) to transit the gate and cross the bar.<\/p>\n

CP 7:7 Item 45 and 46 contain a warning:<\/p>\n

Very dangerous conditions develop over the bar whenever large swells, generated by storms far out at sea, reach the coast. A natural condition called shoaling causes the large swells to be amplified and increase in height when they move over the shallow water shoals. This piling up of the water over the shoals is worsened during times when the tidal current is flowing out (ebbing) through the Golden Gate. Outbound tidal current is strongest about 4 hours after high water at the Golden Gate Bridge and attains a velocity in excess of 6 knots at times. The incoming large swells are met by outbound tidal current causing very rough and dangerous conditions over the bar. Steep waves to 20 or 25 feet have been reported in the area. Mariners should exercise extreme caution as the bar conditions may change considerably in a relatively short period of time.<\/p>\n

The most dangerous part of the San Francisco Bar is considered to be Fourfathom Bank. Bonita Channel, between the shoal and the Marin coast, can also become very dangerous during large swell conditions. The safest part of the bar is the Main Ship Channel through the center of the bar. But even that area can be extremely dangerous when the tidal current is ebbing.<\/p>\n

CP 7:7 Items 149 through 152 discuss currents in the area.\u00a0 In essence, the ebb goes straight out, and begins to fan as it goes across the bar.\u00a0 However, the main strength of the current runs parallel to the south edge of Potatopatch Shoal, and through the Main Ship channel.\u00a0 The flood runs straight in, with a slight set to the north shore.\u00a0 Heavy rips and overfalls can be found at each of the four corners of the Golden Gate (Lime Point at the north tower of the bridge, Fort Point and the south end of the bridge, Point Lobos near Mile Rocks, and Pt Bonita to the northwest)\u00a0 \u00a0Overfalls at Point Bonita can extend 1\/4 mile south into the strait. Eddys, rips, and overfalls can be extreme near the south tower of the bridge, and can cause even large ships to veer off course.<\/p>\n

\"\"<\/a>Once through the gate, crossing the bar through the Main Ship Channel is generally safest.<\/p>\n

A\u00a0 forecast of conditions across the bar and through the Main Ship Channel is at:\u00a0 \u00a0https:\/\/marine.weather.gov\/MapClick.php?zoneid=pzz545#<\/a>.<\/p>\n

Point 1 on safety out the gate:\u00a0<\/strong> Time your exit to minimize the impact of dangerous currents.\u00a0 Generally, the slack before flood is best.<\/em><\/p>\n

Channels across the San Francisco Bar<\/strong><\/h2>\n

There are two channels across the San Francisco Bar.<\/p>\n