Page images
PDF
EPUB

erly and westerly winds. There are some rocks close to the west point at the entrance.

Northeast Bay (chart 8841), at the northeast end of Sanak Island, affords temporary anchorage about 14 mile south-southeastward from Northeast Point in about 13 fathoms (23.8 m). Small vessels may anchor between Northeast Point and Eagle Rock, slightly favoring the point, with Chernabura Island just open of Northeast Point, in 6 to 9 fathoms (11 to 16.5 m), sandy bottom. The bay is exposed to easterly winds.

Northeast Point, forming the north side of Northeast Bay, is about 100 feet (30 m) high. Eagle Rock, about 50 feet (15.2 m) high, lies near the middle of the bay; it is surrounded close-to by a ledge which covers, and a sunken reef connects it with the head of the bay. Water can be obtained by boats at the head.

There are steep and prominent rocky bluffs on the northeast shore of Sanak Island just to the northwestward of Finneys Bay.

Lida Anchorage is a temporary anchorage in southerly winds, at the west end of Caton Island, south of Lida Island, and which may be entered on either side of the latter.

Approaching Lida Anchorage from eastward stand in near the visible rocks off the east end of Lida Island, taking care to avoid the partially covered reef, nearly 1,2 mile eastward of Lida Island, which extends in a northerly direction from Caton Island. Anchor about 14 mile from Caton Island, and 14 to 12 mile southward of Lida Island, in 6 to 7 fathoms (11 to 12.8 m), sandy bottom; care should be taken not to approach the south side of the anchorage.

Approaching Lida Anchorage from westward steer for the southwestern side of Caton Island on a 144° true course, passing about 38 mile southward of Lida Island, and leaving a rock awash, lying 1/2 mile northward from Wanda Island, about 38 mile on the starboard hand, and anchor as directed above. The western end of Lida Island should not be approached closer than 12 mile.

CATON ISLAND is rolling but comparatively low, the grass-covered land rising in places to elevations of 120 to 170 feet (37 to 52 m). There are steep and prominent bluffs on the northwest point of the island. The eastern side is low and fringed with rocky ledges to an average distance of 12 mile offshore. The southern side is also fringed with rocky ledges to as far as 1 mile offshore. Heavy breakers extend a considerable distance offshore, and the entire south side of the Sanak Islands excepting perhaps Peterson Bay is dangerous to approach by a stranger.

The beaches on Caton Island are for the most part composed of rocky ledges or boulders and gravel.

Whale Bay, on the northeast side of Caton Island, is extremely shoal.

Caton Harbor is a large area with general depths of 2 to 3 fathoms (3.7 to 5.5 m), sandy bottom, on the southwest side of Caton Island, protected on the south by Elma Island and on the northwest by the islands and reefs, above water in many places, between Caton Island and Sanak Island. It is protected from all swells, and schooners of considerable size have wintered here. These waters provide the best all-weather anchorage for small vessels in the Sanak Islands. Fresh water in small quantities may be obtained.

[blocks in formation]

Princess Rock, off the west end of the islet in the center of Caton Harbor, is the most prominent feature in the vicinity.

The best entrance channel to Caton Harbor is from the northward. It is narrow and is close to the west end of Caton Island. To enter the harbor from the south through Devils Pass (westward of Elma Island) or through the pass eastward of Elma Island requires local knowledge to avoid reefs and breakers. These passes should not be attempted by a stranger. Surveys in progress (1937) indicate a controlling depth of 112 fathoms (2.7 m.) in the approach to Devils Pass with deeper water through the narrow part of the pass. The tide rips in Devils Pass are at times dangerous to small craft.

To enter Caton Harbor from northward proceed as directed for entering Lida Anchorage from westward, and when well past the rock awash, mentioned under Lida Anchorage, bring the south side of the rock awash in range with Northeast Point astern, and stand in, keeping the range astern, course 125° true, until close to Caton Island. Then keep the bare rocks and kelp projecting from Caton Island close aboard on the port hand, but do not approach the kelp on the starboard hand; the least depth found in the narrowest part of the passage was 412 fathoms (8.2 m), shoaling inside to 312 and 3 fathoms. When past the rocks on the port hand steer about 193° true about 1/2 mile, and anchor in about 3 fathoms (5.5 m) with Princess Rock (high, grassy on top, extensive surrounding reefs covered at high water) in line with Sanak Mountain, bearing 294° true. This anchorage is about 12 mile from Caton Island, and the same distance from the nearest reef on the western side. Anchorage, with probably better shelter from northeast gales, can be made off the sand beach on Caton Island, just inside the narrow entrance.

Peterson Bay (chart 8841), on the south side of Sanak Island, is well protected from all but southeast winds, especially for small vessels, of 12 feet (3.7 m) or less draft, which can anchor well inside the bay. It is reported that during heavy northeast winter gales a heavy swell makes into the bay. The entrance is nearly 12 mile wide. In the widest part of the bay near the head there are depths of 12 to 14 feet (3.7 to 4.3 m). There is a 114-fathom (2.4 m) spot in mid-channel about 1/2 mile inside the south entrance point. Another shoal of 134 fathoms (3.3 m) marked by heavy kelp lies about 350 yards off the south shore and about 14 mile inside the south entrance point. The mean rise and fall of tide is about 412 feet (1.3 m).

To enter Peterson Bay-In approaching from eastward give the east and southeast sides of Caton Island a berth of about 2 miles to clear the reefs and the breakers which extend more than 1 mile offshore, and steer 262° true passing 1 mile southward of Umla Island and Telemitz Island. When the latter island is abeam bring the tangent of the north side of Peterson Bay in line with the slight saddle between Sanak Peak and the eastern shoulder of Sanak Mountain, and run in on this range, course 318° true. When the south point of the bay is about 34 mile distant, haul northward a little so as to bring the north side of the bay in line with the extreme southwest tangent of Sanak Mountain, and run in on this range, course 311° true, until the south point at the entrance bears 177• true. Then steer 294° true for the middle of the bay but avoid the 11/4-fathom spot southward of the course, and select anchorage according to draft. The survey ship Discoverer in 1937 did not enter Peterson Bay but anchored in 12 fathoms (21.9 m) 0.9 mile 112° true from the tip of the south entrance point.

Hague Rock, 9 miles north-northeastward from Sanak Island, is a rocky, grass-covered islet, about 40 feet (12 m) high, with deep water close-to, except on its northern side. A reef extends about 1 mile in a northwesterly direction. The channel between Hague Rock and Sanak Island was surveyed in 1936 and found to be clear and deep. Two E. D. rocks charted previous to 1937 as lying in this channel do not exist, and this channel may be safely used by ships bound from seaward to Ikatan Bay and False Pass. Caton Island should not be approached closer than 112 miles. The foul area to the eastward of Hague Rock has not been surveyed. The channel between Hague Rock and Sanak Island has been used several times by large steamers proceeding directly to sea from Ikatan Bay.

Chernabura Island, 14 miles north-northeastward from Sanak Island, is grass-covered and composed of gently rolling hills about 100 feet (30 m) in height. It is reported that there are cattle on the island.

10. ALEUTIAN ISLANDS

This chain of islands (charts 8802, 9102) is a prolongation of the formation of the Alaska Peninsula, sweeping in an arc 900 miles or more to the westward and forming the southern limit of the Bering Sea. The islands fall into various groups, of which the Fox Islands, Islands of the Four Mountains, Andreanof Islands, Rat Islands, and Near Islands are the most important.

The topographic features are uniformly rugged; the islands are mountainous, and the shores bold, with numerous off-lying islets, rocks, and reefs. In the absence of surveys, the only safe assumption is that these features are duplicated beneath the surface of the water. At all times in approaching the land, therefore, vessels should be navigated with great caution. Surveys are being carried westward from Unimak Island and in 1937 have progressed to and including parts of Unalaska and Umnak Island. The regions to the westward are imperfectly charted with the exception of Nazan Bay. The charts are compilations from various sources and based principally on early Russian explorations.

In addition to the lack of surveys, navigation in this region is made difficult by the prevailing thick weather and further by the lack of knowledge of the currents which attain considerable velocity at times.

A great many of the Aleutian Islands are now utilized as fox farms and owners object to landing on the islands or any other interference, claiming that if the foxes are disturbed in any way, especially in the spring or early summer the yield of pelts is diminished. In some cases, a keeper lives on the island, usually in the winter. Sheep raising is an industry on some of the islands and it is reported that there are now 12,000 head of sheep on Umnak Island.

CURRENTS, Aleutian Islands.-Southward of Latitude 50° N., there is an eastward drift across the Pacific. An eddy, accompanying this flow sets westward along the south shore of the Alaska Peninsula and the Aleutian Islands and then drifts through the passes into the Bering Sea. These currents form a part of the general circulation of the North Pacific Ocean,

Through the Aleutian Island Passes, the velocities of the currents caused by tidal and wind effect are sufficiently large to mask the continuas northward drift through the passes. In the past, numerous reports have been received to the effect that the flood currents flowing into the Bering Sea are very much stronger than the ebb currents. These reports have been largely discounted by observations over a period covering several tides, which reveal equally strong ebb currents flowing through the passes from the Bering Sea. It is believed that on account of the large diurnal inequality in the tide of this region, mariners have been deceived by the length of the duration of the flood.

All passages in the Aleutian Islands have strong currents. On account of the scarcity of reliable observations definite current predictions cannot be made. The effect of the tidal currents has often been felt offshore at a considerable distance from the passes, resulting in unexpected sets. Mariners should guard against such contingency. In the region of the Aleutian Islands the navigator must heed the currents carefully; a vessel is in more danger there from that cause than from any other, except the lack of surveys.

Tidal currents and rips, Fox Island Passes. In the vicinity of the passes the tidal currents are strong and their direction and times of change are uncertain; they are somewhat influenced by winds. In navigating near the entrances, these currents should be kept in mind as they may be felt at a considerable distance. Precautions should be taken to guard against being set into dangerous localities, especially in thick weather. In bad weather, the currents cause much heavier seas, and this effect has been noticed as much as 20 miles off

the passes.

In general, tide rips occur to the southward of the passes on the ebb and to the northward on the flood, furnishing a rough means of determining the set of the current, although local tide rips may be caused by detached banks.

Tide rips even well off the entrances may appear as broken, choppy seas, with a few steep, short swells near the edge. In rough weather, the effect is to make the seas higher and steeper. The tide rips are much more noticeable during periods of tropic tides.

Whirls are more likely to occur in the passes near the times of slack water.

À characteristic of the currents in the vicinity of the passes is the sudden change from slack to strength of flood. A change from slack to almost 2 knots in 10 minutes has been noted, and in many cases the maximum flood occurs within 112 hours after slack. It is therefore probable that the worst tide rips occur at the first of the flood, and under exceptional combinations of weather and tropic tides an effect resembling a bore may be caused in the narrower passes.

In Unimak Pass (p. 308) the current is probably strongest between Scotch Cap Light and Ugamak Island, where at strength of flood and ebb the velocity averages about 3 knots, but the maximum may exceed this figure considerably. A maximum ebb of 5 knots was observed.

The current has a large diurnal constituent which at times of tropic tides may cause the current to set continuously in a flood direction for as much as 18 hours. The ebbs preceding and following these long flood periods have larger velocities but, of course, much shorter duration than the floods.

The predictions for Unimak Pass published in the Pacific Coast Current Tables give an indication of what current may be expected, but these predictions are based on meagre data and should be used with caution.

The set of the flood between Scotch Cap Light and Ugamak Island averages about 295o true. Farther to the westward it is about 325° true. The variation in the set of the current increases the difficulty of navigating Unimak Pass. A vessel proceeding from Unimak Pass

« PreviousContinue »