4. All vessels shall go to the right and pass through the right-hand opening of the draw.

5. Between the hours of 7.20 a. m. and 7.45 a. m. daily, except Sunday, the draw shall not be opened for the passage of vessels other than police or fire boats and vessels employed or controlled by the United States Government. The "delay signals prescribed in rule 3 shall be continuously displayed during the closed periods herein specified.

6. The bridge draw shall habitually be swung so as to open away from an approaching vessel; that is, in a direction contrary to the motion of the hands of a clock.

7. Tugboats, launches, barges, and other small and low craft shall lower their poles or masts whenever by so doing they can pass under the bridge, and the bridge shall not be required to open for such boats, launches, barges, or other small or low craft.

8. These rules and regulations shall be in force on and after October 15, 1925, and will supersede the regulations approved October 2, 1924, for this bridge.

Rules and regulations for the three bridges across the Tidal Canal of Oakland Harbor

Between the hours of 8 a. m. and 4 p. m. of every day the draws shall be promptly opened upon the approach of any vessel or water craft desiring to pass through said bridges, and may remain closed during the remaining hours of every day: Provided, That whenever the interests of navigation, as determined by the Secretary of War, shall require longer or other hours for the opening of the said bridges, the same shall be provided for by the county of Alameda upon notice from the Secretary of War.

Oakland, the second largest city on the bay, is situated on the eastern shore opposite San Francisco. The inner harbor has been improved by dredging San Antonio (Oakland) Creek and by the construction of several well-equipped terminals.

Oakland Harbor is under the jurisdiction of the city of Oakland, and is entirely separate from the Port of San Francisco. In 1925 the controlling depth at the entrance to San Antonio Creek was 27 feet (8.2 m.) at mean lower low water, with a least depth of 2812 feet (8.7 m.) to the Brooklyn Basin. The South Channel through the basin is being dredged to a project depth of 30 feet (9.1 m.) at mean lower low water, with a turning basin at its eastern end, and the project calls for a continuance of the 30-foot (9.1 m.) channel through the Tidal Canal to the Park Street Bridge. It is expected that the project depths will be attained in the spring of 1927.

Shipyards.-A large shipyard with building ways, marine railways, and extensive repair facilities, is located on the north side of the channel, 2 miles eastward of the entrance. There are several other shipyards located on the Oakland and Alameda sides.

Oakland Creek is crossed by the Webster Street Bridge, with two openings. The signal for opening the bridge is three long blasts of the whistle. (See preceding table for details.)

Oakland Mole, just north of the Oakland Harbor entrance, is the terminus of the Southern Pacific Railroad, and is used largely for passenger and automobile ferry service. A channel with a least depth of 22 feet (6.7 m.) at mean lower low water and marked by range boards has been dredged through the flats to the three freight piers at the southern side of the outer end of the mole.

Key Route Mole, just north of the Oakland Mole, extends southwestward from Emeryville to a point within 12 mile of Goat Island, and is used for passenger ferry traffic only.

Outer Harbor.-Between the Oakland and Key Route Moles, the city of Oakland has dredged a channel to 30 feet (9.1 m.) at mean lower low water, leading to a shipyard and several wharves along a northerly extension of the Oakland Mole.

Alameda, immediately southward of Oakland, is of little commercial importance. A railroad mole and wharf, parallel to and southward of San Antonio Creek, projects about 2 miles westward from the western part of the town, and forms a part of the south jetty of San Antonio Creek.

Berkeley, the seat of the University of California, is a rapidly growing city northward and adjoining Oakland. The Berkeley wharf has been condemned and is not in use (1925). In clear weather, the Campanile at the university shows prominently from the bay.

West Berkeley and Emeryville, on the bay shore northward of Oakland, are small manufacturing towns. Several wharves, accessible for light-draft vessels at high water, are built out within their limits.

Point Richmond (Richmond Harbor), on the eastern shore of the bay, nearly 4 miles southward from Point San Pablo, is the terminus of the Santa Fe Railroad, and an important oil-refining

center.

The inner harbor has been improved by dredging a channel from deep water off Point Richmond toward Point Potrero thence to the northward to Ellis Landing. The controlling depth to Ellis Landing in 1925 was 19 feet (5.8 m.) at mean lower low water. There were depths of 24 feet (7.3 m.) in the channel leading to the municipal wharf on the south side of Point Richmond.

The railway-car ferry slips are built out from Point Richmond just northward of the dredged channel. A fog signal sounding 1 blast every 15 seconds has been established on the end of the Santa Fe ferry slip. There is also an automobile ferry slip just southward from the car ferries. Midway between Point Potrero and Point San Pablo there are a large number of oil tanks.

Port Orient and Winehaven are shipping points located southward of Point San Pablo, and have wharves built out to the channel. At the former large vessels load refined oil.

Sausalito, on the western shore about 2 miles northward from Lime Point, is the terminus of a railroad extending northward to Humboldt Bay. The anchorage off Sausalito is much used by yachts and small pleasure craft. There is passenger and automobile ferry service to San Francisco.

Richardson Bay, northward of Sausalito, is shoal and of little importance commercially.

Belvedere, on the eastern shore of Richardson Bay opposite Sausalito, is a summer resort and of little commercial importance. Tiburon, near Point Tiburon, is the terminus of a railroad connecting with interior northern points.

California City, 1⁄2 mile northward from Bluff Point, is a naval coaling station.

Several small towns and villages, of little commercial importance, on both shores of the bay south of San Francisco, are reached at high water by narrow sloughs winding through the marshes,

The United States military reservations, embracing Fort Point and Black Point, are on the northern shore of the peninsula. Channels. From the Golden Gate to the anchorage off San Francisco and southward to Point Avisadero, and northward to the entrance of San Pablo Bay, the channels are wide, and have ample depth at low water for deep-draft vessels. The most important dangers are described above.

From Point Avisadero, the southern end of the bay is reached by a rather narrow channel, marked by beacons, following the western shore, and gradually decreasing in width from 211⁄2 miles at its northern end to less than 1/4 mile at its junction with Alviso Slough near the southern end. This channel is used principally by lightdraft steamers and sailing vessels, engaged in transporting farm produce from some of the landings reached by the sloughs connecting with the channel.

CURRENTS, SAN FRANCISCO BAY AND TRIBUTARIES

Immediately outside the bar there is a slight current to the northward and westward, known as the coast eddy current. The currents at the San Francisco light vessel are described in some detail under currents at lightships, page 286. The currents most affecting navigation in this vicinity are the tidal currents. Across the bar the flood current converges toward the entrance, with a preponderance from the southward, so that it is felt sooner around Point Lobos than around Point Bonita, and around both points earlier than across the Main Ship Channel. The ebb current spreads from the entrance over the bar, but the main strength is westsouthwestward, parallel with the southern edge of the Four Fathom Bank, and through the Main Ship Channel. It is not strong across the Four Fathom Bank, and is hardly felt at all in the Bonita Channel, where, on the contrary, during the middle of the ebb a slight eddy current has been observed setting east-southeastward. In the vicinity of Mile Rocks the currents attain a considerable velocity within a few minutes after slack on both flood and ebb.

In the Golden Gate the flood current sets straight in, with a slight tendency toward the north shore, and with heavy overfalls both at Lime Point and Fort Point when strong. It causes an eddy in the bight between Point Lobos and Fort Point. The ebb current has been observed to have a velocity of more than 62 knots between Lime Point and Fort Point and sets from inside the bay on the north side toward the latter point. Like the flood current, it causes an eddy in the bight between Fort Point and Point Lobos, and a heavy rip and overfall reaching about 1/4 mile southward from Point Bonita.

In the Golden Gate the current attains its average maximum rate (2.8 knots) inward about 2 hours before the time of high water at Fort Point and its average maximum rate (3 knots) outward 12 hours before the time of low water.

Slack water in the Golden Gate occurs on the average approximately 12 hours after the time of high water at Fort Point and 2 hours after the time of low water.

When the diurnal inequality in the tide is considerable the ebb stream turns to flood about 2 hours after the time of higher low

water.

Daily predictions of the times of slack water and the times and velocities of maximum flood and ebb in the Golden Gate, together with factors and differences for obtaining the times and velocities of the current for other points in San Francisco Bay, are given in the Pacific Coast Current Tables.

Inside the Golden Gate the flood current sets mainly northnortheastward and northeastward and causes swirls from the Golden Gate as far eastward as Alcatraz and Angel Islands and through Raccoon Strait, northward of the latter island. The ebb current, inside the Golden Gate, is felt first along the south shore. In the Golden Gate the duration of the ebb stream is somewhat greater than that of the flood. At periods of great freshets in the Sacramento and San Joaquin Rivers there have been instances of very slight surface current, or none at all, on the small flood in the Golden Gate.

Along the water front of San Francisco the current turns from flood to ebb approximately two hours earlier than in the Golden Gate (shortly before the time of high water at Fort Point), and from ebb to flood 12 hours earlier than in the Golden Gate (about one hour after the time of low water at Fort Point). Farther out in the bay the current turns somewhat later.

When the land water discharge is small, the time of the currents in San Pablo Bay, off Mare Island, and in Suisun Bay, follow the times of the currents in the Golden Gate by approximately one, two, and three hours, respectively.

For a detailed description of tides and currents in San Francisco Bay, see United States Coast and Geodetic Survey Special Publication No. 115. This document may be purchased from the Superintendent of Documents, Government Printing Office, Washington, D. C., at the price of 20 cents. It gives the results of a systematic current survey made in 1923.

GENERAL REMARKS ON APPROACHING SAN FRANCISCO BAY

Vessels approaching San Francisco Bay in clear weather, by day or night, will experience no difficulty in making a landfall, as the aids to navigation, both natural and artificial, are prominent and easily distinguished. From northward, vessels will make Point Reyes, and when up with the point can lay a course for the light vessel, observing proper care to avoid Noonday Rock northward of the North Farallones, or use the Bonita Channel, as prudence and inclination direct. From seaward, vessels should make the Southeast Farallon and shape a course for the lightship. From southward, vessels should make the lightship, or if desiring to cross the bar southward of the Main Ship Channel make Point Bonita Lighthouse and use the South Channel, or cross westward of the channel, as prudence and the condition of the bar warrant.

In thick weather, which prevails during a considerable portion of the year, vessels approaching from any direction must exercise great caution. The currents are variable and uncertain, at times

attaining considerable velocity. A detailed description of the conditions which may be encountered and the precautions which should be observed is given on page 25.

Vessels equipped with radio should not fail to obtain radio bearings from the three stations located in the vicinity of the entrance, while those equipped with the radiocompass should get frequent bearings from the San Francisco Lightship. (See Radio Service on p. 10.)

From northward vessels endeavor to make Point Reyes fog signal. This signal may not be heard in the bight northward of the point, but the lead will indicate the position. If inside the 30fathom (55 m.) curve and the signal is not heard, the vessel should be put broad offshore. Under certain conditions of foggy weather it has sometimes been found difficult to locate the signal, owing to deflection in the direction of the sound, but by following the 30fathom (55 m.) curve closely a vessel can round the point safely.

Cordell Bank lies about 20 miles 277° true (W. by S. mag.) from Point Reyes. Within the 30-fathom (55 m.) curve it is about 2 miles long in a northwest and southeast direction, with a width of about 2 miles. The least water given on the bank is 25 fathoms (46 m.), rocky bottom, but 19 fathoms (35 m.) have been reported. Between the bank and Point Reyes the depths increase to 66 fathoms (121 m.); outside the bank the depths increase rapidly to 100 fathoms (183 m.) in 2 miles, and over 200 fathoms (366 m.) in 3 miles. Vessels from northward are sometimes guided by soundings on Cordell Bank, provided they can verify their soundings by the depths and characteristics of the bottom.

Strangers are advised not to use the Bonita Channel in thick weather. The approaches lead past Duxbury Reef, on which many vessels have been lost under similar conditions, and after passing the reef, unless the buoys are plainly seen and distinguished, the channel, on account of its comparatively narrow width, is dangerous to those not thoroughly familiar with it.

From westward vessels should exercise the greatest caution when inside of 100 fathoms (183 m.), and if inside of 50 fathoms (91 m.) should head offshore and wait for clear weather or a pilot, unless the fog signal on the Southeast Farallon can be made. This signal can not be heard well from northward, especially during northerly or northwesterly winds. If northward of the Farallones, the 50fathom (91 m.) curve followed southward should lead within sound of the fog signal, after making which a course can be shaped for the lightship.

From southward vessels make the fog signal at Pigeon Point or Point Año Nuevo and lay a course to pass about 3 miles off Montara Point, when the fog signal at that point should be made; the depths should not be shoaled to less than 25 fathoms (46 m.). When abreast Montara Point a course can be shaped for the lightship, and the lead will be a good guide in approaching it and the bar.

Strangers without a pilot, after crossing the bar, are advised to anchor in about 10 fathoms (18.3 m.) and wait for a pilot or clear weather. Unless one is thoroughly familiar with the characteristics of the fog signals in the entrance and the peculiarities of the currents, entering in thick weather is hazardous, as the lead is of little value in the Golden Gate.