DIRECTIONS, SAN FRANCISCO BAY.

In the choice of the channel to be used in entering strangers should be guided by the following considerations:

The South Channel should be used only in clear weather and with a smooth or only moderately rough bar.

The Main Ship Channel should be used in thick weather unless the bar is inclined to break.

The Bonita Channel should not be used in thick weather. It may be used at any time when the aids can readily be seen, and at such times, if the bar is breaking, should be used in preference to the Main Ship Channel.

In thick weather and with the bar breaking strangers should stand offshore and wait for more favorable conditions.

Having these considerations in mind, the following directions, which connect with the coastwise directions given on page 31, may be used to enter by any of the above channels.

1. By the South Channel.-From a position 2 miles west-southwestward of Pigeon Point Lighthouse, steer 344° true (NW. by N. mag.) for 221/2 miles to Point Montara Lighthouse abeam, distant 2 miles. Then steer 7° true (N. by W. mag.) for 13 miles to a position 400 yards west-southwestward of red buoy No. 2 S. Then steer 357° true (NNW. mag.) for 23% miles, passing 100 yards westward of buoy No. 4, and when Seal Rocks are abeam, distant 11⁄2 mile, change to 33° true (N. by E. 14 E. mag.) for 11 miles to Mile Rocks light abeam, distant 1/4 mile. Then steer 51° true (NE. by N. mag.) for 21/2 miles to Lime Point light abeam, distant 3⁄4 mile, and proceed as directed in section 4 following.

2. By the Main Ship Channel.-Having made the lightship, bring Fort Point Lighthouse to bear 70° true (NE. 5% E. mag.) with Alcatraz Island Lighthouse in range, and steer for it on that range until Point Bonita Lighthouse bears 344° true (NW. by N. mag.). Then make good a 60° true (NE. 14 N. mag.) course until Lime Point is abeam, distant 3% mile. Then proceed as directed. in section 4 following. The above range leads over the axis of the new dredged channel over the bar.

3. By the Bonita Channel.-From a position 11⁄2 miles southwestward of Point Reyes, steer 114° true (E. 2 S. mag.) for 18 miles to a position 1/4 mile southwestward of Duxbury Reef gas and whistling buoy. Many vessels have been lost on Duxbury Reef, and great caution is essential on this course. The lead should be used constantly, and the vessel should be stopped a little short of her distance to the buoy to listen for its fog signal. Under no conditions should the vessel proceed beyond this point until the buoy has been located.

From the buoy steer 102° true (E. 11⁄2 N. mag.) for 61⁄2 miles to 1/4 mile northward of Bonita Channel gas and whistling buoy. Then steer 134° true (SE. by E. 34 E. mag.) for 24 miles, passing 100 yards southwestward of Bonita Channel gas and bell buoy, mile southwestward of Bonita Point Lighthouse, and to a position with the light bearing 356° true (NNW. mag.) distant 3⁄4 mile. Then steer 76° true (NE. by E. 1% E. mag.) for 25% miles to Lime Point Lighthouse abeam, distant 3⁄4 mile.

After passing Bonita Channel gas and bell buoy, the channel is marked by a lighted range, of which Mile Rock Lighthouse is the front range, and a fixed red light on a black box on top of a large white square building approximately 400 feet (122 m.) above water, is the rear range. The building carrying the rear range light is the new California Palace of the Legion of Honor at Landsend, Point Lobos.

Steamers leaving San Francisco Bay through the Bonita Channel on the ebb tide must mind their starboard helm when crossing the tide rip off Point Bonita. When the bow passes the rip the stern is thrown to port and, unless promptly met, the vessel is headed straight for the rocks off the point.

4. If bound to the anchorage off San Francisco, from a position about 3 mile southeastward of Lime Point Lighthouse, steer 93° true (ENE. 5% E. mag.) for 234 miles, heading for the northeastern point of Goat Island and passing a little over 1/4 mile northward of Presidio Shoal gas buoy and 1/2 mile southward of Alcatraz Island Lighthouse. Then haul southward and follow the water front of San Francisco at a distance of about 1/2 mile. Anchor as desired in any of the anchorages shown on chart 5532.

If bound to San Pablo Bay or Mare Island Strait, vessels can use the following courses, which lead over a rocky area with a least depth of 30 feet (9.1 m.) westward of Alcatraz Island in a least depth of about 32 feet (9.8 m.) (1925) in the dredged channel through San Pablo Bay and about 31 feet (9.4 m.) (1925) in Mare Island Strait.

From a position 3 mile southeastward of Lime Point Lighthouse steer 63° true (NE. mag.) for about 3/4 miles, giving Point Blunt a berth of 11⁄2 mile. Round Point Blunt at this distance and steer 335° true (NW. 1 N. mag.) for 43% miles heading for the western one of the Marin Islands, passing 1/4 mile northeastward of Quarry Point and Point Simpton (Angel Island) and 3 mile southwestward of Red Rock Bank buoy to a position with Red Rock abeam. distant mile. Then steer 3° true (N. by W. % W. mag.) heading for the western one of The Sisters, off Point San Pedro, and passing westward of Invincible Rock and Whiting Rock buoys to East Brother Island Lighthouse abeam, distant 11⁄2 mile.

From this position, steer 40° true (NNÉ. mag.) for 5 miles to the gas and bell buoy at the southwestern end of the dredged channel. The courses through the dredged channel are 58° true (NE. 12 N. mag.) for 214 miles to the bend, then 79° true (NE. by È. % E. mag.) for 24 miles to the gas and bell buoy at the eastern end.

If bound to Mare Island Navy Yard, from this position steer 74° true (NE. by E. mag.) for 15% miles, to a position 1⁄4 mile south-southwestward of the entrance to the strait, with a black buoy 1 mile on the port beam. Then steer north-northeastward for 1/4 mile to a position midway between the ends of the jetties and then follow the channel to a point midway between the black gas buoy and the red buoy opposite it. From this point steer 330° true (NW. 14 W. mag.) for 13% miles, then follow a 318° true (NW. by W. 1⁄2 W. mag.) course to a point off the navy yard.

SAN PABLO BAY

(chart 5533) is a nearly circular basin of water about 10 miles long in a northeast and southwest direction, with a greatest width of about 8 miles. The northern part consists of low marshes intersected by numerous sloughs with a large area of shoal water and mud flats that bare at extreme low tides. The southern shore is bolder, except between Point San Pablo and Pinole Point, where it is low and marshy for about 3 miles. At its eastern end it communicates with Suisun Bay by Carquinez Strait, and by Mare Island Strait northward with Napa Creek. There is considerable traffic through the bay; deep-water vessels pass through to load grain at points on Carquinez Strait, and to South Vallejo to load flour and discharge lumber, while many oil tankers and sugar-laden vessels pass through the bay bound for Crocket and Martinez.

Light-draft vessels, sail and steam, pass through for points on Suisun Bay and the Sacramento and San Joaquin Rivers, and on Petaluma and Napa Creeks.

The main channel through the bay extends in a gentle curve northward and eastward from the entrance to the eastern end of the bay. The average width between the 18-foot (5.5 m.) curves is a little over 114 miles, being a little wider at the southern end and about 3/4 mile wide at the eastern end. The channel across Pinole Shoal has been improved by dredging, and in 1925 the controlling depth was 32 feet (9.8 m.) at mean lower low water. The dredged channel is marked on the north side by gas and bell buoys at each entrance, and a gas buoy at the turn.

Point San Pablo is described on page 90.

There are several landings on the southern shore of San Pablo Bay used by light-draft vessels; on the northern shore McNears Landing, near Point San Pedro, is the most important.

Petaluma Creek enters San Pablo Bay at its western end. It is improved under a project to obtain a least depth of 5 feet (1.5 m.) to the turning basin, thence 4 feet (1.2 m.) to the head of navigation in the city of Petaluma, which is the center of an extensive poultry and egg industry. In 1925 there were depths of 62 feet (2 m.) through the flats to the entrance of the creek, 4 feet (1.2 m.) to the turning basin, 22 feet (0.8 m.) in the turning basin, and gradually shoaling above. The full project depths were to be restored by dredging in 1925.

Considerable amounts of farm and dairy produce are carried in small vessels, and general merchandise is received. There is a regular freight service with San Francisco. A bell buoy and an echo board have been established near the entrance to the channel across the flats. This channel is marked by lighted beacons, and above the entrance the chart is the guide. The creek is crossed by a railroad drawbridge near its mouth.

Pinole Point is a moderately high, rocky bluff projecting 1 mile from the southeastern shore of San Pablo Bay, with a wharf built out from the east side of it. Powder works are located on the point, and 2 miles back of it there are numerous oil tanks, known as a "tank farm." Shoals and flats bare at low water extend from

Point San Pablo to Pinole Point, and from Pinole Point northeastward to Lone Tree Point.

The Selby Smelting Works, on the southern shore abreast Mare Island, are prominent. There is a wharf here with 30 feet (9.1 m.) alongside.

Ferry slip.-Just westward of Selby there is a ferry slip, connected to the highway by a high trestled viaduct.

Landmark. The high white pyramidal skeleton towers on each side of Carquinez Straits that carry electric-power cables across the straits are prominent in clear weather. The cables are too high to interfere with passing vessels.

Mare Island Strait (chart 5525) opens into San Pablo Bay at its eastern end, on the eastern side of Mare Island. It leads to South Vallejo and Vallejo on its eastern side and the navy yard on its western side, 2 miles above the entrance. A channel about 30 feet (9.1 m.) deep and 600 feet wide, widened to 1,000 feet abreast the navy yard, has been dredged from the entrance to the navy yard. It is subject to some shoaling and is redredged at intervals. The depth in 1925 was about 31 feet (9.4 m.). It is well marked by lighted beacons and buoys. The channel is contracted by jetties on each side at the entrance (both marked by a lighted beacon on the end), and in several places above the entrance. (For direction see page 102.)

Carquinez Strait Lighthouse (cream-colored tower on dwelling) is on the jetty on the eastern side of the entrance to Mare Island Strait, 230 yards from its end; there is a lighted beacon and fog signal (air siren) on the end of the jetty.

South Vallejo, on the eastern shore of Mare Island Strait inside the entrance, is the terminal of a railroad connecting with interior northern points. A large flour mill is located southward of the railroad wharf, and lumber wharves northward; they are prominent in entering. From 10 to 21 feet (3.0 to 6.4 m.) at low water can be taken alongside, depending on the locality. Communication may be had by rail and steamers with other points on the bay; there are also telegraph and telephone facilities.

Vallejo, about 1 mile above South Vallejo, is a town of little commercial importance. It supplies a large amount of fresh provisions to the naval station and affords residences for the employees and others attached to it; it also serves as a distributing point for a considerable agricultural area in its vicinity. Communication with San Francisco and other points may be had by rail and steamer; a ferry makes regular trips to the navy yard. There is a regular launch freight service to Napa at the head of navigation on Napa River. The United States naval station, located on the western side of Mare Island Strait, has two dry docks and extensive facilities for repairing and building vessels of all sizes. A time ball is dropped from a building near the ferry gate at noon, one hundred and twentieth meridian, or 20h. Om. Os. Greenwich civil time.

There is a bridge with a draw span connecting Mare Island with the city of Vallejo at the northern end of the navy yard.

Napa River, the continuation of Mare Island Strait above the navy yard, has been improved by dredging, and in 1925 there was a least depth of 6 feet (1.8 m.) mean lower low water to Napa, 17

miles from the entrance to Mare Island Strait. The mean tidal range is about 5 feet (1.5 m.) and the river channel is subject to some shoaling. A considerable amount of farm and dairy produce is carried in vessels of 4 to 6 feet (1.2 to 1.8 m.) draft, steam and sail, to and from various points on the creek. The channel is marked by lighted beacons and buoys, and is easy to follow with the aid of chart 5533.

Directions through San Pablo Bay and Mare Island Strait to the navy yard are given on page 102.

For currents see page 98.

CARQUINEZ STRAIT

(chart 5534) connects San Pablo and Suisun Bays and is about 6 miles in length in a general easterly direction. For the first 32 miles it is a little less than 12 mile in width, and then expands to a width of about 1 mile. It is deep throughout with the exception of a small stretch of flats on the northern shore, and a smaller area in the bight on the southern shore near the eastern end. There are several small settlements on both shores.

A highway bridge crossing the straits at Semple Point is under construction (1925) with one pier located in the middle of the strait. The bridge will be high enough to clear all shipping.

Benicia, on the northern point at the eastern entrance, is the largest town. The United States Army reservation and arsenal are located at the eastern end of the town. The car ferry of the Southern Pacific Railroad between Port Costa and Benicia lands at the western part of the town.

A shoal spot, with a least depth of 10 feet (3 m.) at mean lower low water, lies 1/2 mile 137° true (SE. by E. 12 E. mag.) from the light on the car-ferry slip at Benicia.

Crockett, on the southern shore, is built around a large sugar refinery. The wharves accommodate the deep-draft vessels that discharge sugar from the Hawaiian Islands.

Port Costa, on the southern shore, ships a large amount of wheat. Extensive warehouses for storing the grain occupy a considerable portion of the southern shore of the strait.

Martinez, on the southern shore, in the bight near the eastern entrance, is a small town of little commercial importance. There are two wharves off the town, one for the automobile ferry service to Benicia, and the other for light-draft vessels with local freight. Just to the eastward of the town are two piers built out to deep water, and used for handling oil.

Bullhead Point shows as a rounding hill and is 100 feet (30.5 m.) in elevation. The high brick chimney located on the point is prominent. There is an oil-refining plant here with many storage tanks located between it and Martinez.

SUISUN BAY

(chart 5534) is a broad, shallow body of water with marshy shores, and filled with numerous marshy islands, a large number of which have been reclaimed and are now under cultivation. It is practically