(183 m) extend so close to the beach that a vessel cannot count on getting bottom with the lead in time to prevent disaster. Point Sur, therefore, should be given a wide berth. If, on this track, the weather has not cleared by the time Piedras Blancas has been reached, the vessel should be hauled out 2° or 3°, and great caution should be exercised as Point Sur is approached.

The lead should find bottom off Point Sur, but even if it does not, no difficulty should be experienced in making a landfall northward of Monterey Bay, as the depths shoal very gradually from the 100fathom (183 m) curve to the beach. The track to the lightship may then be followed by means of sounding.

Detailed local knowledge is necessary for entering the Golden Gate in thick weather, because of the strong, irregular currents and tide rips. At times, however, it will be clear within the Heads when it is foggy outside. It is well, therefore, to stand in cautiously as far as bell buoy no. 7; if from that vicinity Point Bonita cannot be seen, the vessel should be anchored until the weather clears. Southbound.-The courses from the bar to Point Sur are short and should be easy to make good, especialy as the 100-fathom (183 m.) curve extends well offshore to the northward of Point Sur, affording ample opportunity for checking the vessel's position by sounding as the point is approached.

Likewise, on the long course from Point Sur to Point Arguellonorthward of Point Arguello the soundings extend well offshore and the point may be reached without difficulty. If the lead shows 30 fathoms (55 m), haul to a south-southeast (mag.) course, keeping in that depth, and if the water deepens to over 40 fathoms (73 m) the vessel will be past the point, and may be hauled up for Point Conception.

Again, in approaching Anacapa Island, soundings may be used to guide the vessel to within sound of the fog signal. A fix should be obtained off Anacapa Island before attempting to approach Point Vicente.

Point Vicente, formerly considered the most difficult point to make on the southward track, is now marked by a light and fog signal. Deep water extends so close to the point that the navigator will get an echo from his whistle before he gets bottom with the lead. From Anacapa Island, the course should be shaped to pass about 2 miles off Vicente, and the lead should be used as the point is approached.

Guided by the soundings, Los Angeles Harbor Lighthouse can be made after passing Point Fermin.

Strangers should not attempt to enter Los Angeles inner harbor in thick weather without a pilot.

Vessels bound from Los Angeles to San Diego usually experience little difficulty in making Point Loma. If in doubt, the course may be shaped to pick up the 30-fathom (55 m) curve to the northward of the point, and that depth followed to the fog signal. The presence or absence of kelp just inside the 30-fathom (55 m) curve is a good guide in deciding whether the vessel is north or south of the point.

Strangers should not attempt to enter San Diego Bay in thick weather without a pilot.

SAN FRANCISCO TO COLUMBIA RIVER AND TO THE STRAIT OF

FUCA

Courses and distances

(Abbreviations: Pt., Point; Lt., Light; Id., Island; t., true; dist., distant)

No. 4. San Francisco to Strait of Fuca (charts 5052, 5502, 5602, 5702, 5802, 5902, 6002, 6102)

No. 5. San Francisco to Columbia River (charts 5052, 5502, 5602, 5702, 5802,

5902)

No. 6 Columbia River to the Strait of Fuca (charts 6002, 6102)

The following brief summary of the methods actually employed in thick weather by the ablest masters on the coast indicates the methods and precautions by which safety is assured:

Northbound.-Taking the departure from Point Bonita, there should be no trouble in making the lightship and very little in making Point Reyes, if the track is checked by sounding.

Approching Point Arena, start sounding when off Gualala and continue until assured that the ship is not inside the track. The differences in the bottom characteristics north and south of the point are a good guide. Point Arena fog signal will nearly always be heard north and south of the point, but seldom when abeam if over 2 miles distant.

When within 10 miles of Punta Gorda soundings should be taken as rapidly as possible, as the depths shoal abruptly; also, with soundings taken infrequently, there is a possibility with wire sounding that the lead will drop in the successive submarine valleys, entirely missing the shoal areas in between and resulting in the dangerous and erroneous conclusion that the vessel is wide of the point. If Punta Gorda is passed in not less than 50 fathoms (91 m) the vessel will also clear Blunts Reef. If, however, the course is changed at Cape Mendocino without making the lightship, sounding should be continued long enough after the change to make certain that the vessel is not behind her reckoning.

Soundings need not be taken again until approaching the shoal off Rogue River. Here the bottom should be searched for in the same manner as in approaching Punta Gorda, as the soundings obtained on this shoal give a check on the latitude and indicate any change of course necessary in approaching Orford Reef, 20 miles beyond. If less than 60 fathoms (110 m) is obtained the ship should be hauled out at least a point and, in any case, the lead should again be used in approaching Orford Reef. The lead may find no bottom off the reef, but to the northward of Cape Blanco bottom, fine, gray sand will be found in 70 to 80 fathoms (128 to 146 m) if the vessel is near the track.

If bound for the Columbia River the vessel, after passing Cape Blanco, will be within soundings obtainable with the lead for practically the entire distance. If uncertain of the position, edge in to a depth of 32 to 35 fathoms (58 to 64 m) anywhere between Cape Meares and Tillamook Rock and steer northwest in that depth and the fog signal on Tillamook Rock will usually be heard. At times difficulty may be experienced in hearing this fog signal, even when passing it in that depth. However, if the vessel keeps outside the 30-fathom (55 m) curve she cannot get into trouble, and the change in direction of that curve is a good indication of the time at which the vessel passes Tillamook Rock. The lightship can then be made by following the 30-fathom (55 m) curve.

Vessels bound for the Strait of Juan de Fuca frequently steer one course from Blunts Reef Lightship, Cape Mendocino, applying to the true course the mean of the magnetic variations. This causes the track to curve away from the shores during the first half of the distance, approaching them during the remainder. Approaching the strait, if the position is uncertain, stand in to pick up the 30fathom (55 m) curve in the vicinity of Cape Elizabeth or Destruc

tion Island and follow that depth to make Umatilla Reef Lightship. Thence the short distance to Tatoosh Island may be traversed without difficulty.

Southbound. Taking the departure from Umatilla Reef Lightship steer one course for Cape Mendocino as described above. Use the lead to pick up Heceta Bank, as vessels may overrun their distance, particularly during the summer. The time required in crossing the bank gives a good determination of the vessel's position at the time the lead drops again into deep water.

Cape Blanco should be passed with caution. If soundings taken show less than 60 fathoms (110 m), haul out parallel to the coast until the depths are increased materially; the vessel will then be past Cape Blanco. Recent surveys show the area off Cape Blanco to be of even bottom with the 60-fathom (110 m) curve 51⁄2 miles off the cape. Vessels from the Columbia River should use the lead frequently to guard against an inshore set. Vessels at times have encountered a strong set on or offshore in the region between Heceta Bank and Cape Arago, when none was apparent farther northward. Cape Blanco should be rounded as described in the preceding paragraph. After passing Orford Reef there are no dangers until in the vicinity of Cape Mendocino. Currents setting the vessels directly on or offshore have been reported between Trinidad Head and Čape Mendocino and for that reason, as the former point is approached, an occasional deep sounding should be taken, and from the time the vessel is abreast of Table Bluff the lead or other means of sounding should be used frequently. If in doubt as to the position, the vessel should be hauled inshore to pick up the 30-fathom (55 m) curve somewhere off Table Bluff; then hauled out parallel to the shore, keeping in depths of 30 to 35 fathoms (55 to 64 m) until the lightship is made.

This course should lead across the head of a submarine valley about 10 miles northwest of Cape Mendocino. Here the navigator may lose the bottom (unless equipped with echo sounding apparatus) as the depths drop off suddenly to 200 fathoms (366 m), but in about 3 miles bottom should again be picked up in about 60 fathoms (110 m). Cape Mendocino is a dangerous point and many vessels have been lost here. The mariner can not be too careful in rounding this point. The charts now show complete hydrographic surveys of this area, and should be studied carefully with the soundings obtained. After changing course the sounding should be continued to pick up the submarine valleys south of the cape.

Approaching Point Arena, start sounding 10 or 15 miles north of the point, and if at any time the lead shows 40 fathoms (73 m) or less, haul out on a south (magnetic) course in not less than 40 fathoms (73 m). In this way the fog signal will usually be made; if not, and the water deepens to 60 fathoms (110 m), the vessel will be past the point and the course may be changed for Point Reyes. Arena Rock, with 13 feet (4.0 m) over it, is only 34 mile inside the 30-fathom (55 m) curve.

Point Reyes fog signal should be made before proceeding beyond it and if the vessel's position has been located off Point Arena little difficulty should be experienced in doing so, as the soundings are distinctive if started early. But if the vessel has passed wide of

Arena without obtaining a fix, caution is necessary, as the soundings may be misleading. Practically the same chain of soundings can be obtained in the vicinity of Cordell Bank as on the regular track passing Point Reyes, and vessels, although sounding frequently, have been known to find themselves in the midst of the Farallones while still anxiously trying to pick up Point Reyes. An occasional sounding should, therefore, be taken after passing Point Arena to verify the distance off land.

In the immediate vicinity of Point Reyes the character of the bottom is a better indication of the position than are the depths. North of the point the lead will bring up a muddy substance; south of it, gray sand. This indication is particularly valuable in the area to the northward and eastward of the point.

Having made Point Reyes fog signal, there should be little difficulty experienced in making the light vessel, provided the lead is used to check the course.

Detailed local knowledge is necessary for entering the Golden Gate in thick weather, because of the strong, irregular currents and violent tide rips. At times, however, it will be clear within the heads when it is foggy outside. It is well, therefore, to stand in cautiously as far as lighted bell buoy no. 7; if from that vicinity Point Bonita cannot be seen, the vessel should be anchored until the weather clears.

SAN DIEGO BAY AND APPROACHES (CHARTS 5105, 5107)

The entrance to San Diego Bay lies about 10 miles northwestward from the boundary between the United States and Mexico. The bay is the best natural harbor south of San Francisco and affords perfect protection in any weather. From the entrance, which is about 1/4 mile in width, it expands to a width of 11⁄2 miles, curving sharply eastward for 5 miles, where it contracts to 3% mile between San Diego and Coronado. From this point it extends southeasterly for 711⁄2 miles, expanding to a shallow basin 2 miles wide, through which a well-marked channel leads to a point 5 miles above San Diego. The head of the bay is separated from the ocean by a low, narrow, sand spit, which at its northern end expands to a width of 1 mile and is nearly divided by Spanish Bight, dry at low water.

San Diego, population 147,995 (1930 census), on the eastern shore about 5 miles from the entrance, is the principal city on the bay. The depths at the wharves vary from 18 to 33 feet (5.4 to 10.0 m), according to the locality. The municipality maintains two modern piers, capable of accommodating large modern vessels. These two piers have a depth alongside of 33 feet (10.0 m) at mean lower low water. They handle practically all of the general cargo of the port. There is a large amount of foreign and domestic commerce by rail and water. Petroleum products, lumber, fresh fish, cement, steel, and general merchandise are imported; fruit, farm produce, canned fish, cotton and cottonseed products and general merchandise are exported. The customs barge office, maintaining a 24-hour guard service, is located on the municipal Broadway Pier.

National City, population 7,301 (1930 census), on the eastern shore, 311⁄2 miles southward of San Diego, is of no maritime importance; it is connected with San Diego by rail.