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these stations is to lead mariners to the light vessels off harbor entrances.
Where only one radio compass station is available, the mariner may fix his position by two or more bearings from the station with the distance run between, or may use the bearings as a line of position, or as a danger bearing. Or the bearing may be crossed with a line of position obtained from an observation of an astronomical body to establish a fix.
Wave Jengths.—All independent and group radio compass stations keep watch on 800 meters. Only this wave should be used to call and work with these stations.
Calling a radio compass station. To obtain a bearing from independent radio compass stations, call the station from which the bearing is desired in the usual manner and request bearings by means of the conventional signal given hereafter. Simultaneous bearings from two or more compass stations can be obtained by making the call include the other compass stations desired. To obtain bearings from the harbor entrance compass stations, carry out the procedure previously given. The compass control station only will answer.
Conventional signals.—The following abbreviated signals will be used:
The following radio compass stations will be of use for vessels approaching the Pacific coast of the United States:
Cattle Point, Wash..
Lat. 48° 27' 04" N., lon. 122° 57' 45'' W.
1 Limited service. Standing watch during thick and heavy weather.
3 Limited service. Standing watches: 0000 to 0200; 0400 to 0600; 0800 to 1400; and 1600 to 2200 (G. M. T. civil).
PROCEDURE IN DETAIL.
(a) A ship calling the radio compass station or compass control station should make the abbreviation “QTE?" ("What is my bearing?"). This request will be answered by the radio compass station or control station, and when ready to observe the radio bearing it will send the signal “K," indicating to the ship to commence
testing”; i. e., repeating its distinguishing signal for a period of 50 seconds. The signal should be made slowly with the dashes considerably prolonged.
(6) The testing should be made on 800 meters, upon the completion of which the ship should await reply from the radio compass station.
(c) The radio compass station or control station will then reply, repeating the abbreviation “QTE”. (“Your bearing from
degrees”), followed by the bearing in degrees given by a group of three figures 000 to 360, indicating the true bearing in degrees of the ship station from the radio compass station, and then the time group giving the time of observations in local standard time. In the case of more than one radio compass 'connected by land line only, the station originally called will answer. This station will combine all the bearings taken by itself and associated stations into one message, which gives each bearing observed immediately after the name of the station making the observation. All compass
stations transmit on 800 meters. Danger from reciprocal bearings.-Attention is invited to the fact that when a single bearing is furnished there is a possibility of an error of approximately 180°, as the operator at the compass station can not always determine on which side of the station the vessel lies. Certain radio compass stations, particularly those on islands or extended capes, are equipped to furnish two corrected true bearings for any observation. Such bearings when furnished vessels may differ by approximately 180°, and whichever bearing is suitable should be used.
Caution.—Mariners receiving bearings which are evidently the approximate reciprocal of the correct bearing should never attempt to correct these bearings by applying a correction of 180°, as such correction would not include the correction necessary on account of deviation at the compass station. An error of as large as 30° may be introduced by mariners applying an arbitrary correction of 180° to such bearings. Vessels receiving bearings manifestly requiring an approximate 180° correction should request the other bearing from the radio compass station if not previously furnished.
Bearings, except in the case of approximate reciprocal bearings, should be accurate within 2° of arc provided the transmitting equipment on board vessels is tuned sharply to 800 meters. Operators should use sufficiently wide coupling to obtain low decrement. If radio transmitters are not tuned sharply, it is difficult to obtain bearings that are sufficiently accurate for navigational purposes. When bearings from three or more compass stations are not over 2° of arc in error, but do not meet at a fixed point, the geometric center of the triangle formed by the bearings can generally be taken as the approximate position of the vessel. Mariners until thoroughly familiar with the system are advised to use radio compass stations frequently, especially in clear weather, when positions of vessels can be accurately fixed in order to accustom operators to the procedure and to acquaint themselves with the degree of accuracy and dependability of bearings furnished by the radio compass stations.
Reports.-In order that the operation of shore radio compass stations may be checked, mariners obtaining bearings are requested to forward a brief report to the Director Naval Communications, Navy Department, Washington, D. C., containing the following particulars:
1. Name of ship. 2. Name of radio compass station. 3. Date and local standard time at which radio bearing was taken. 4. Bearings given by radio station.
5. Estimated position of ship at above time and dates by methods other than radio.
6. The probable degree of accuracy of the estimated position.
There is no charge for bearings furnished by the U. S. Naval Radio Compass Station.
Radio FOG SIGNALS.-The following radio fog signal is operated on the Pacific coast by the United States Lighthouse Service: San Francisco Light Vessel, Calif.-Series of double dashes for 30 seconds, silent 30 seconds.
These radio fog signals are intended for the use of vessels equipped with radio compass. By reason of this radio compass (also termed radio direction finder) the bearing of the radio fog signal station may be determined with an accuracy of approximately 2o and at distances considerably, in excess of the range of visibility of the most powerful coast lights. The apparatus is simple and may be operated by the navigator without the assistance of a radio operator or without knowledge of the telegraph code. The radio directionfinding apparatus consists of a radio receiving set, similar in operation to those used for radio telegraph or telephone reception, and a rotatable coil of wire in place of the usual antenna. By, rotating the coil the intensity of the signal received from the transmitting station is caused to vary, and by noting the position of the coil when the signal is heard at its minimum intensity the bearing of the transmitting station is readily obtained.
The signals from the light vessels have definite characteristics for identifying the stations, as have the flashing lights and sound fog signals, and bearings may be obtained with even greater facility than sight bearings on visible objects. The radio fog signals are transmitted on a wave length of 1,000 meters, which is exclusively reserved for this purpose to avoid interference. The stations transmit continuously during thick weather and also for one-half hour twice each day, beginning at 9 a. m. and 3 p. m., regardless of weather conditions.
A general description of this method of navigation and the instruments required may be obtained from the Commissioner of Lighthouses, Washington, D. C., upon request. The Bureau of Standards Scientific Paper No. 428, the Radio Direction Finder and Its Application to Navigation, may be obtained from the Superintendent of Documents, Washington, D. C., for 15 cents.
the largest of the islands, is at the southeast end of the group. It is irregular in shape, resembling a triangle, and has a greatest length of 83 miles north and south and a greatest width of 73 miles. The island is dominated by the two principal peaks, Mauna Loa and Mauna Kea, each almost 14,000 feet high, from the summits of which the land slopes gradually to the coast, with occasional cinder cones and lesser peaks intervening. In the central western part of the island Mount Hualalai rises to an altitude of 8,269 feet, while in the northwestern part Mount Kohala, elevation 5,505 feet, dominates the Kohala Peninsula. Hawaii, being the youngest of the islands, shows evidences of recent volcanic activity in the numerous lava flows, some of which almost reach the coast, and in the various cinder cones dotting the slopes. The only active volcanos in the Hawaiian group, Mauna Loa and Kilauea, are located on this island.
RIVERS.—There are numerous streams on the east coast, but none are navigable except for boats and small craft.
POPULATION.—By the census of 1920 Hawaii had 64,895 inhabitants.
WINDS.—The easterly trade winds seems to divide at Cape Kumukahi, part following the coast northwestward around Upolu Point, where it loses its force, the other part following the southeast coast around Kalae, where it loses its force. On the west coast of Hawaii, except at Mahukona, the sea breeze sets in about 9 a. m. and continues until after sundown, when the land breeze then springs up. Vessels from westward bound to ports on the windward side of Hawaii should pass close to Upolu Point and keep near the coast, as the wind is generally much lighter than off shore. Sailing vessels from westward bound to ports on the eastern side of Hawaii should keep well northward until clear of Alenuihaha Channel.
RAINFALL.--The rainfall of Hawaii varies greatly in different localities. The greatest amount is found along the windward side. There is moderate rainfall on the Kona district highlands, while a little reaches the Kau district and the west coast.
ANCHORAGES are numerous except on the northeast and southeast coasts, the first requirements under ordinary condition being shelter from the northeast trades.
SUPPLIES.—Provisions, ice, lumber, and some ship chandler's stores can be obtained at Hilo. Some provisions can be obtained at other places.
WATER can be conveniently obtained at Hilo.
REPAIRS.—There is a machine shop at Hilo, where vessels can make extensive repairs.
COMMUNICATION with Honolulu by a regular line of steamers can be had several times a week.
RAILROADS extend northwestward, southeastward, and southward from Hilo. There is a railroad that follows the coast from Mahukona around the north end of the island to within 1 mile of Akokoa Point.
HIGHWAYS.-There are good highways in many parts of the island, and automobiles can be obtained at most of the towns.
TELEPHONE.-There is communication by telephone to all parts of the island and by wireless telegraph to the other islands.
CURRENTS.-Generally the currents follow the trades, but occasionally they set against the wind. A current follows the coast north of Cape Kumukahi around Upolu Point; another one follows the trend of the coast off shore southwestward from Cape Kumukahi around Kalae and northward as far as Upolu Point. There is also a countercurrent inshore that sets southward from Okoe Landing along the west coast around Kalae, and thence northeastward along the shore as far as Keauhou.
NORTHEAST COAST' OF HAWAII.
From Upolu Point to Cape Kumukahi, a distance of 80 miles, the coast has a general southeasterly trend; it is only partially surveyed, but is generally bold. The only known outlying dangers are shoals off Kauhola Point, off Honokaneike Gulch, and Blonde Reef in Hilo Bay. All dangers will be avoided by giving the coast a berth of about 2 miles. There are no harbors or sheltered anchorages on this coast except Hilo Bay. At some of the landings the freight is handled by local vessels, and at most of these, vessels load by means of a wire cable. When running the coast at night, it will be found that the electric lights of the various sugar mills define the coast fairly well.
Upolu Point, the northernmost point of Hawaii, is hard to identify, There are numerous bluffs, forming headlands, in the vicinity, all of which are quite similar from seaward. The country back of the point is covered with sugar cane, and here and there may be seen clumps of trees, among which are generally situated the mills, camps, and villages.
Kauhola Point, 7 miles eastward of Upolu Point, is a low point of land marked by a flashing white light, off which a dangerous reef, generally marked by breakers, extends 3 mile. Vessels should give this point a berth of 1 mile. A fair anchorage, used by local vessels, can be had in Awaeli Harbor, in 9 fathoms, with Kauhola Point light bearing 90° true (E by N mag.), distant 43 mile. In leaving this anchorage, bound eastward, steer 10° true (N mag.) for 1/4 miles to clear the reef.
Keokea (white) Harbor, 192 miles southeast of Kauhola Point, is an abandoned shipping point. It can not be recommended as an anchorage when the trade winds are blowing.
Niulii Plantation, about 1 mile southeast of the harbor, is the eastern terminus of the Hawaii Railway, which is engaged in the transportation of freight from the various plantations along the Kohala coast to Mahukona.
Akokoa Point, 3 miles eastward of Kauhola Point, marks the easterly limits of the sugar plantations in the Kohala district. Southeastward of this point the country has the appearance of a large table-land, rising gradually to the Kohala Mountains, which are heavily wooded to their summits.
The coast between Akokoa Point and Waipio Gulch, a distance of about 10 miles, consists of numerous precipices, ranging in heights up to 1,300 feet, and deep gorges that extend back into the country. There are also numerous waterfalls. The faces of the precipices present a general brownish appearance, although in places they are covered with vegetation from the top to the sea.