NEW YORK TO STRAITS OF FLORIDA

CHESAPEAKE BAY TO CAPE HATTERAS

49

The currents may be expected to set about 20° to the right of the wind up or down the coast. High velocities of current may occur either with heavy gales or with long-continued gales from one direction, the estimated maximum velocity near the coast being 2 to 3 knots. In depths of 20 fathoms (36.6 m) or more, 0.5 to 1 knot is regarded as nearer an average of what may be expected. Currents produced by on-shore winds set inshore as well as alongshore.

Courses and distances, Chesapeake Bay to Cape Hatteras

CAPE HATTERAS TO JUPITER INLET LIGHTHOUSE, FLA.

From Diamond Shoal Lightship there are two routes to the Straits of Florida. Most of the regular lines use the route outside of the Gulf Stream. All vessels bound to any port as far south as St. Johns River follow the coast inside the stream.

Cape Hatteras to Jupiter Inlet Lighthouse, Fla., outer route.-Course 1 to 2.-This course crosses the Gulf Stream. Under ordinary conditions an average allowance should be made for a 1-knot current setting 45° true for the entire run; with northeasterly winds there may be practically no current, while southerly, and especially southwest, winds may increase it considerably. Observations should be obtained as often as possible.

Course 2 to 3.-There is uncertainty as to the currents that may be expected on this run. It is probable that a Gulf Stream set of 0.5 knot against the vessel and, as the Bahama Bank is approached, possibly some easterly drift also will be experienced. With northeasterly winds it is stated that a southwesterly set of 0.5 knot has been experienced. This and the easterly set mentioned are the dangerous one to guard against in order not to overrun and get too close to Matanilla Shoal. Observations should be obtained as often as possible. The establishment of radio beacons and radio direction-finder stations on the Florida coast has greatly facilitated the fixing of position, and their use should not be neglected by vessels in this area. In case of doubt from about latitude 28° N., vessels can stand west

ward and watch the lead carefully to pick up the edge of the bank on the Florida coast northward of Jupiter.

Course 3 to 4.-This course leads across the Gulf Stream for Jupiter Inlet Lighthouse. Matanilla Shoal, marked by Matanilla Shoal Lighted whistle buoy M S, should be given a wide berth. On this course an allowance should be made for a northerly current, averaging about 24 knots for the entire run of about 80 miles. It will, therefore, be necessary to shape the course for a position some 8 or 10 miles southeastward of Jupiter Inlet 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 (183 m) 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.

The courses given in the table, "Cape Hatteras to Jupiter Inlet Lighthouse, Florida, Outside Route", must be corrected for current.

Courses and distances, Cape Hatteras to Jupiter Inlet, Fla., outer route
(Use this table in conjunction with the 4 paragraphs preceding)

Courses and distances, Cape Hatteras to Jupiter Inlet, Fla., inner route (Use this table in conjunction with 3 paragraphs following)

Cape Hatteras to Jupiter Inlet Lighthouse, Florida, Inner route.-The courses southward to position No. 6 off Hetzel Shoal Lighted Whistle Buoy 8 lead in depths of 17 to 20 fathoms (21 to 36 m). In approaching and passing the shoals off Cape Canaveral care must be exercised; the depth should not be shoaled to less than 13 fathoms (22.7 m).

The current of the Gulf Stream may be expected under ordinary conditions to set against the vessel for the entire run with a velocity of about 0.5 to 0.8 knot, the direction of the current following the curve of the coast. It must be remembered, however, that the effect of winds is almost immediately felt on the currents, and that with northerly, and especially northeasterly, winds a current of about 1 knot will set with it along the coast. Southerly, and especially southwesterly, winds increase the velocity of the Gulf Stream.

On course 6 to 7 the 15-fathom (27.4 m) curve is a good guide. The current of the Gulf Stream may be expected under ordinary conditions to have a velocity of about 0.7 knot off Cape Canaveral, increasing to 1.5 or 2 knots off Jupiter Inlet Lighthouse.

STRAITS OF FLORIDA AND THE FLORIDA REEFS

Caution as to currents.-The attention of navigators is called to the fact that most of the wrecks on Florida Reefs have occurred in the case of vessels bound southward, especially at night. They generally occurred on reefs lying about halfway between the lights; and the region of maximum frequency of wrecks was between Carysfort Reef and Alligator Reef, and to a less extent between Fowey Rocks and Carysfort Reef and between Alligator Reef and Sombrero Key. The establishment of intermediate lights has greatly facilitated navigation in this area.

From a consideration of the data it can be stated that nearly all casualties are due to one cause-an underestimate of the strength of the Gulf Stream against the vessel. This leads to two errors in navigation: First, the distance made good over the bottom is less than assumed or indicated by the log, and when skirting the reefs the course is changed too soon for the next light and before sighting it; second, the vessel underrunning her log is closer to the reefs than indicated by the four-point bearing, and this error is greater for slow vessels than for fast ones.

At night, when bound, southward and navigating at a safe distance from the reefs between Fowey Rocks and Sombrero Key, it is on the side of safety to assume that the vessel is steaming against a 3 or 4 knot current and from one light to hold a course that will insure clearing the reefs until the next light is sighted. It is also well to remember that near the reefs there is a tidal current, possibly as much as 0.5 knot in places directly on and off the reefs on the rising and falling tides respectively.

On the other hand, when bound northward and following Florida Reefs between Sombrero Key and Fowey Rocks, it is on the side of safety to underestimate the velocity of the Gulf Stream with the vessel; the courses should be laid well clear of the reefs, which is the usual practice. Vessels are rarely lost on Florida Reefs when

bound northward, except when crossing the stream from Habana and making the reefs in misty or rainy weather.

The following are extracts from a report of a stranding:

Rounded Great Isaac Light at a distance of 24 miles, steered by compass and log 227° true for 20 miles, and then steered 224° true. By bow and beam bearing Fowey Rocks Light was 12 miles distant when abeam, but on account of the northerly current it was probably about 7 miles. The vessel stranded on the north end of Long Reef, having had a northerly set of 17 miles, or an average of about 24 knots for the crossing from Great Isaac Light to Florida Reefs. Along the keys there is a slight tidal drift, of not more than 0.5 knot, setting on and off the reefs. This current will probably not be noticeable at a greater distance from the reefs than 1 mile. Between the keys, in the passes connecting Hawk Channel and Florida Bay, the current has considerable velocity (3 to 4 knots) in the immediate vicinity of the openings and is felt to some extent, probably, on and beyond the usual sailing line in Hawk Channel. When not influenced by winds the maximum current northwestward into Florida Bay and southeastward into Hawk Channel through the openings between the keys occurs about 1 hour before high and low waters, respectively, in the straits. The northwesterly current is increased by easterly winds and the southeasterly current by westerly winds, due to the effect of these winds in driving out or piling up, respectively, the waters in Florida Bay.

Jupiter to Fowey Rocks.-Vessels follow the coast as close as safety permits in the daytime at a distance of 1 to 12 miles to Hillsboro Inlet Lighthouse, then 12 to 2 miles off-and pass 1 mile eastward of Miami Lighted Whistle Buoy No. 2 and Fowey Rocks Lighthouse. Close attention should be given to the lead, and courses not depended upon entirely and checked frequently. From Jupiter to Lake Worth Inlet the depth should not be shoaled to less than 13 fathoms (23.7 m) and then keep in over 15 fathoms (27.4 m). Southward of Lake Worth Inlet the depths increase so rapidly offshore that the hand lead cannot be depended upon to insure safety for deep-draft vessels. A narrow ridge, on which least depths of 7 to 12 fathoms (12.8 to 21.9 m) were found and with somewhat deeper water inside it, lies from 1 to 12 miles from this coast. This ridge has not been closely developed and should be avoided by deep-draft vessels. A vessel with a draft of 23 feet (7.0 m) reports striking at a point 11⁄2 miles from shore and 6 miles southward of Jupiter Inlet Light and another with a draft of 19 feet (5.8 m) at a point 134 miles from shore and 182 miles northward of Fowey Rocks Light. It is suspected that the reported grounding of several steamers on ridges south of New River Inlet is in a measure attributable to the indistinct shore line for which the line of trees along the west edge of the marsh is mistaken, which would place a vessel 1 to 12 miles inshore of her intended position.

The current of the Gulf Stream may be expected to have a velocity of 1.5 knots from well northward of Jupiter until southward of West Palm Beach, then 1 knot to Hillsboro Inlet, and then 0.7 knot to Fowey Rocks. The velocity increases rapidly offshore.

Fowey Rocks to Sand Key.-Vessels follow the Florida Reefs from 1 to 2 miles off in the daytime, and 2 to 4 miles off at night. The position should be checked on the aids as passed and on the lights