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miles off Molasses Reef lighthouse; then 234° true (SW.58 W. mag.) for 161/2 miles to 114 miles off Alligator Reef lighthouse.
From 114 miles off Alligator Reef lighthouse make good the course 234o true (SW.58 W. mag.) for 11 miles to 114 miles off Tennessee Reef buoy (nun, No. 4); then 247° true (SW. by W. 34 W. mag.) for 11 miles to 2 miles off Coffin Patches beacon “C”, then 2520' true (WSW. 1/4 W. mag.) for 9 miles to 114 miles off Sombrero Key lighthouse; then 253° true (WSW. 38 W. mag.) for 17 miles to 13% miles off Looe Key beacon "G"; and then 257• true (WSW. 5/8 W. mag.) for 261/2 miles, passing 11/2 miles off American Shoal lighthouse and to a position 2 miles off Sand Key lighthouse.
At night.-From 2 miles off Fowey Rocks lighthouse make good the course 189°_true (S. 58 W. mag.) for 1372 miles, keeping in the white rays of Fowey Rocks lighthouse, until Carysfort Reef lighthouse is in sight showing white and up to Pacific Reef light, distant off 2 miles; then 205o true (SSW. 18 W. mag.) for 11 miles to a position 2 miles off Carysfort Reef lighthouse.
A number of vessels have been lost on the reefs between The Elbow and Molasses Reef, and extra caution should be observed in this locality. The extremely variable current against the vessel should be carefully considered in determining the position off Carysfort Reef light, from which to shape the course to lead well clear of The Elbow. (The establishment of Molasses Reef lighthouse will undoubtedly minimize the danger in this locality.)
From a position 2 miles off Carysfort Reef light make good the course 212° true (SSW.78 W. mag.) for 161,2 miles to a position 212 miles off Molasses Reef lighthouse; then 234° true (SW.578 W. mag.) for 17 miles to a position 212 miles off Alligator Reef light. The edge of the red sector of Carysfort Reef light leads close to the reefs between the light and The Elbow.
From a position 212 miles off Alligator Reef light make good the course 234° true (SW 578 W. mag.) for 1612 miles until Sombrero Key light is in sight showing white; then 255o true (WSW. 1/2 W. mag.) for 15 miles to 2 miles off Sombrero Key light; then 254° true (WSW. 12 W. mag.) for 23 miles to 214 miles off American Shoal light; and then 259• true (WSW.78 W. mag.) for 2012 miles to 2 miles off Sand Key Light.
SAND KEY TO DRY TORTUGAS. On the south edge of Florida Reefs between Sand Key and Dry Tortugas there is broken ground with rocky, very uneven bottom, which, like other parts of Florida Reefs, rises abruptly from the deep water of the Straits of Florida. As a measure of safety this broken ground, including the areas with depths less than 10 or 12 fathoms lying southward and westward of Rebecca Shoal and Dry Tortugas, should be avoided by vessels of the deepest draft. The 50-fathom curve is about the least depth that can be depended upon to insure clearing this broken ground when skirting it, except southwestward and westward of Dry Tortugas. A vessel is reported to have struck an obstruction with about 18 feet over it lying 11 miles 147° true (SE. 78 S. mag.) off Rebecca Shoal lighthouse; the least depth found in this locality by a careful examination is 512 fathoms. A vessel is also reported to have struck an obstruction 2 miles 285° true (WNW.78 W. mag.) off Rebecca Shoal lighthouse.
STRAITS OF FLORIDA TO CAPE HATTERAS.
The currents near the edge of the bank in this locality are variable, being influenced by the winds, by differences in barometric pressure in the Gulf and outside, and by the tides. There are strong tidal currents through the passage westward of Rebecca Shoal; a velocity of 1.5 knots has been observed in the passage, and 1.0 knot (north and south) on the edge of the bank southward of the passage. The tidal current on and off the edge of the reef should also be considered.
From a position 2 miles off Sand Key lighthouse make good the course 2650 true (W.5/8 S. mag.) for 41 miles, passing nearly 4 miles southward of Marquesas Rock nun buoy, the same distance southward of a gas and whistling buoy marking a wreck 212 miles westward of Marquesas Rock, and to a position 13 miles from Rebecca Shoal lighthouse bearing 8o true (N. 42 E. mag.). Then make good the course 287° true (WNW. 34 W. mag.) for 27 miles to a position 1112 miles 228° true (SW. mag.) of Dry Tortugas lighthouse.
DIRECTIONS, STRAITS OF FLORIDA TO CAPE HATTERAS. On the eastern side of the Gulf of Mexico for a distance of possibly 100 miles outside the 100-fathom curve, southeasterly currents prevail and velocities as high as 2.5 knots have been reported. The Gulf Stream investigations indicated that the strongest current into the Straits of Florida is found near the 1,000-fathom curve westward of Dry Tortugas, and that velocities of 1.5 to 2 knots are frequent in that locality. Approaching Dry Tortugas from the Gulf should therefore be regarded as a difficult run, as a vessel will overrun her log, and observations are the principal guide; currents may be expected at all times, but variations occur both in direction and velocity, due to the season of the year and the winds. Approaching the passage westward of Rebecca Shoal from northward, a number of vessels have stranded on New Ground Shoal, indicating an easterly set.
From Florida Straits to Cape Hatteras, vessels follow the Gulf Stream, pass about 12 miles southwestward of Dry Tortugas lighthouse, about 14 miles southward of Rebecca Shoal lighthouse, then follow Florida Reefs about 8 miles off, and pass Fowey Rocks at a distance of 10 to 12 miles and Jupiter Inlet lighthouse 15 miles. The velocity of the current varies greatly in different localities, and is also subject to sudden changes, due to wind, differences in barometric pressure, and the like, so that no fixed hourly rate can be given. Frequently high velocities will be carried between certain points, and suddenly dropping off between others. The position should therefore be checked whenever possible by bearings. The ship speed plus supposed rate of current should not be assumed to fix the position. The greatest velocity will be found between Carysfort Reef and Jupiter Inlet, ranging from 2 to 412 knots.
From 15 miles off Jupiter Inlet lighthouse make good the course 1° 30' true (N. 18 E. mag.) for 208 miles to latitude 30° 25' N., longitude 79° 40' W. This should lead from 12 to 18 miles outside the 100-fathom curve and should give a current nearly equal to the average made between Fowey Rocks and Jupiter.
From latitude 30° 25' N. and longitude 79° 40' W. make good the course 26° true (NNE. 38 E. mag.) for 50 miles to latitude 31° 10'
N., longitude 79° 15' W. Then 45° 30' true (NE. 14 E, mag.) for 243 miles to latitude 34° 00' N., longitude 75° 50' W.
It is stated that between latitude 30° 30' and 32° 30' N. heavy tide rips will be experienced, indicating a change in the direction of the stream and not an increase in the velocity, and creating in stormy weather a very uncomfortable sea.
From latitude 34° 00' N. and longitude 75° 50' W. make good the course 22° true (NNE. 38 E. mag.) for 69 miles and pass eastward of Diamond Shoal light vessel. Then follow the tracks to ports northward as described in the southbound routes on page 36.
When approaching Diamond Shoal great care must be taken to have a correct location for the vessel. The currents are subject to wide variations, as indicated by the observations on the light vessels. At times during both summer and winter the Gulf Stream has great velocity; at other times none will be found, or a southerly set may be experienced with northerly winds. The general direction of the stream is northeast with a velocity of 1 to 2 knots, but on nearing Diamond Shoal light vessel the current is said to set well to the eastnortheast and at other times nearly north. Overallowance and this northerly set have been fatal to many vessels. If a northerly gale is encountered between Jupiter and Cape Hatteras, some navigators keep closer inshore to get on soundings before reaching Diamond Shoal.
The courses given from Jupiter to Hatteras follow nearly the axis of the Gulf Stream. If followed, the best current will usually be obtained, but good observations are essential to avoid overrunning or underrunning. Due regard should be given to the seasons of the year. It is stated that winter currents are much lighter, often dropping to nothing after long spells of northerly and northeast winds.
DIRECTIONS FOR ENTERING STRAITS OF FLORIDA THROUGH PROVIDENCE CHANNELS.
The greater number of sailing vessels bound to the Gulf of Mexico from ports in Europe, British North America, or the northern Atlantic ports of the United States, and a large number of steamers from European ports, enter the Straits of Florida from eastward through the Providence channels, which have a least width of 22 miles between Great and Little Bahama Banks.
The point for which a course is shaped, and the first land sighted, is the south point of Great Abaco Island, known as Hole in the Wall. Vessels coming from northward, if at all doubtful of their reckoning, should make latitude 26° 30' N., well eastward of the eastern end of Abaco Island, so that in case the wind falls light or the weather becomes thick they will not be picked up by Elbow Key. At night, in a sailing vessel, if the wind is from southward when in this locality. and the light is not sighted or the reckoning is doubtful, the vessel's head should be kept eastward, as the lead will be of little use to give warning of danger. Near the northeastern end of Great Abaco Island the currents are strong and variable and have caused many wrecks in the vicinity of Elbow Key.
Caution:—A branch of the North Equatorial Current runs strongly on the eastern side of Bahama Islands, and several vessels have stranded between Hole in the Wall and Elbow Key. The current
generally sets north-northwestward; its velocity is about 1.5 knots, increased during southeast winds, but it sometimes sets in an opposite direction.
In the Northeast Providence Channel the currents are variable and the reefs and keys should not be approached too closely in light winds. In the Northwest Providence Channel, between Great Stirrup Key and Great Isaac, the flood sets southward on the Great Bahama Bank and the ebb northward off the bank. In the middle of the channel there is generally but little current, except after northerly winds, when it frequently sets eastward with a velocity of about 1 knot. The tidal current has a velocity of about 1 knot on the banks, setting directly on and off on the rising and falling tide, respectively.
Steamers bound to ports in the Gulf of Mexico, after passing Great Isaac, will find it to their advantage to stand across the Straits of Florida for Fowey Rocks Lighthouse and follow the Florida Reefs into the Gulf. The reefs are so well marked in the daytime, and at night by the red sectors in the lights, that no uncertainty as to the position of a vessel is possible with ordinary care. This route is also shorter than the one along the western edge of Great Bahama Bank and across Salt Key Bank.
Sailing vessels after passing Great Isaac stand along the western edge of Great Bahama Bank for a distance of about 75 to 80 miles and then stand for the northwest end of Salt Key Bank; or, if not over 18 feet draft, they can cross Salt Key Bank, passing either side of Dog Rocks (30 feet high) and south of Double Headed Shot Keys, thus avoiding the strength of the Gulf Stream, which is weaker here than on its western side. From Salt Key Bank the wind generally decides whether the vessel bound into the Gulf of Mexico crosses the Straits of Florida so as to make Sand Key lighthouse, or follows the north shore of Cuba and crosses the straits so as to pass westward of Tortugas.
Vessels of less than 12 feet draft can stand across the northwest end of Great Bahama Bank after entering the Northwest Providence Channel, but this should not be attempted unless in the daytime, when the rocky patches can be seen so as to be avoided. A vessel using this route will leave the western edge of Great Bahama Bank about 78 miles southward of Great Isaac lighthouse, and southward of Orange Key.
THROUGH PROVIDENCE CHANNELS TO GREAT ISAAC AND FOWEY Rocks.--When Hole in the Wall lighthouse is made, shape the course to pass from 3 to 5 miles southward of it; a narrow bank of soundings with depths of 9 to 12 fathoms extends 5 miles between the bearings southeastward and east-southeastward from Hole in the Wall. Then make good a 281° 30' true (W. by N. mag.) course for 100 miles, passing 5 miles northward of Great Stirrup Key lighthouse and to a position near the edge of the bank with Great Isaac lighthouse bearing_231o true (SW. 12 W. mag.) distant 7 miles. Then round Great Isaac lighthouse at a distance of about 4 miles in a depth of about 12 or 13 fathoms.
The principal dangers are the Gingerbread Ground and the rocks and reefs lying between it and Great Isaac lighthouse, which have a total length of about 30 miles; and the greatest caution and attention to soundings should be observed in approaching this dangerous
locality, as the flood tide sets directly on the reefs, and in places parts of it are only about 11/2 miles from the edge of the bank. From westward of Stirrup Keys to eastward of the Gingerbread Ground the northern edge of the bank is clear and the lead a safe guide, and vessels sometimes anchor here during light winds.
From northward of Great Isaac lighthouse steamers shape the course across the Gulf Stream for Fowey Rocks lighthouse. On this course an allowance should be made for a northerly current, averaging about 214 knots for the entire run. It will therefore be necessary to shape the course for a position some 8 or 10 miles southeastward of Fowey Rocks light to allow for the northerly set. When fixing the position by bearings on the light, keep in mind that while outside the 100-fathom curve the vessel is probably in the full strength of the Gulf Stream, where the northerly current may average a velocity of 4 knots; if the light is on the starboard bow, the vessel will be much closer to it than indicated by the distance run between the successive bearings on it. On account of the strong current and the abrupt shoaling inside the 100-fathom curve the greatest caution should be observed in approaching Fowey Rocks and in fixing the position from which to shape the course southward. (See the caution as to currents in the Straits of Florida on p. 38.)
TO STAND ALONG THE WESTERN EDGE OF GREAT BAHAMA BANK.If possible, daylight should be selected for the run.
Having rounded Great Isaac lighthouse at a least distance of 3 miles, steer 223° true (SW. 14 S. mag.) for 10 miles to pass outside Eldorado Shoal (depth 10 feet), taking care in the night not to come within the depth of 10 fathoms, or to bring the light to bear northward of 51° true (NE. 12 E. mag.) until the shoal is passed. The course may then be altered more southward to follow the edge of the bank in not less than 10 fathoms and pass outside Moselle Shoal buoy.
After passing North Bemini the keys must be closely hugged in order to avoid the Gulf Stream, which sometimes comes close to the rocks. A short calm within a mile of the edge of this part of the bank might drift a sailing vessel so far northward as to oblige her to run around Little Bahama Bank and to enter again from eastward. Therefore, instead of attempting to beat along
with a light wind it is more prudent to anchor under North Bemini and await a slant of wind to get around the elbow.
In the winter when near Great Isaac, if the weather indications give warning of a northwester, it is advisable for a sailing vessel to remain in the Northwest Providence Channel and be guided by bearings on Great Isaac until the wind draws northward, which it usually does in 24 to 48 hours.
Vessels proceeding westward from Great Bahama Bank should endeavor to strike soundings on the northwest end of Salt Key Bank. Should the wind be scant from westward they may run in on the bank on either side of Dog Rocks and pass off southward of the Double Headed Shot Keys; or, should the wind be light and tending to calm, they may anchor on the bank to avoid being set northward. At night vessels had better run down westward of the bank, paying great attention to the lead.
It is advisable for sailing vessels not to stand over for Salt Key Bank until after reaching Orange Key. In the summer months, when