after the time of the corresponding strengths and slacks at Chesapeake Bay entrance. The approximate times of the four phases of the current refer to the time of tide at Old Point Comfort, are as follows: Slack water before flood, 1/4 hour before high water. Slack water before ebb, 34 hour before low water. Off Smith Point Lighthouse.-Slack water before the flood occurs about 314 hours after the time when the current turns northwest at Chesapeake Bay entrance (or approximately 1/2 hour after high water at Old Point Comfort), and slack water before the ebb occurs about 314 hours after the time when the current turns southeast at Chesapeake Bay entrance (or approximately at time of low water at Old Point Comfort. Between Smith Point and Point Lookout.—A considerable set to the eastward due to an ebb current and to the westward due to a flood current is frequently experienced. The strengths of flood and ebb current occur about 334 hours after the corresponding strengths at Chesapeake Bay entrance (or approximately 334 hours after high water and 21⁄2 hours before high water, respectively, at Old Point Comfort, or 1/2 hour before low water and 1/4 hour before high water, respectively, at Baltimore). The approximate mean velocity at strength of flood is 12 knot and at strength of ebb 1 knot. Off Point No Point.-The current is inclined to be irregular and velocities at strength are generally less than 1 knot. On the average the slack waters occur about 5 hours after the corresponding slacks at Chesapeake Bay entrance. Referring to the tide at Old Point Comfort the slack before flood occurs about 24 hours after high water and the slack water before ebb occurs about 134 hours after low water. Referred to the tide at Baltimore the slack water before flood occurs about 24 hours before low water and the slack water before ebb about 22 hours before high water. Strengths of flood or ebb have average velocities of about 1/2 knot. Off Hooper Island Lighthouse.-All phases of the current occur about 51/2 hours after the times of the corresponding phases at Chesapeake Bay entrance. The slack before flood occurs about 134 hours before low water at Baltimore, and the slack before ebb occurs about 2 hours before high water at Baltimore. Strengths of both flood or ebb have average velocities of about 11⁄2 knot. Off Cove Point.—All phases of the current occur about 534 hours after the corresponding phases of the current at Chesapeake Bay entrance. The slack water before flood occurs about 12 hours before low water at Baltimore and the slack water before ebb occurs about 134 hours before high water at Baltimore. The average velocity of the current at strength is about 3/4 knot for both flood and ebb. Off Sharps Island Lighthouse. The slack waters and strengths of flood and ebb current occur about 7 hours after the corresponding slacks and strengths at Chesapeake Bay entrance. Slack water before flood occurs about 1/4 hour before the time of low water at Baltimore and slack water before ebb occurs about 1/2 hours before the time of high water at Baltimore. Off Sandy Point Lighthouse. The slack waters and the strengths of flood and ebb current occur about 834 hours after the corresponding slacks and strengths at Chesapeake Bay entrance. The slack before flood occurs about 12 hours after low water at Baltimore and the slack after ebb occurs about 14 hours after high water at Baltimore. The average velocity of the current at strength of flood or ebb is about 34 knot. Proceeding from Sandy Point toward Baltimore the velocity of the current diminishes rapidly. At Seven Foot Knoll the average velocity at strength of flood or ebb is about 12 knot. At Fort McHenry.-The tidal current is very weak and the velocity and direction of flow depends mainly upon the wind. Off Worton Point. The slack water and the strengths of the flood and ebb occur about 10 hours after the time of the corresponding slacks and strengths at Chesapeake Bay entrance. The slack before the flood occurs about 3 hours after the low water at Baltimore and the slack before ebb occurs about 22 hours after high water at Baltimore. The average velocity of the strength of flood is about 114 knots and the average velocity of the strength of ebb is about 111⁄2 knots. Further current information for Chesapeake Bay is given in the current tables for the Atlantic coast of the United States. These tables include the predicted times of slack water and the predicted times and velocities of strengths of flood and ebb for Chesapeake Bay entrance for each day of the year for which they are issued. They also contain a current diagram of Chesapeake Bay with explanation and a table of differences and constants by means of which the predicted times and velocities of the current at a large number of places in Chesapeake Bay and its tributaries may be obtained. These tables may be purchased for 10 cents per copy from the Coast and Geodetic Survey or its sales agents. GENERAL REMARKS, APPROACHES TO CHESAPEAKE BAY The prominent landmarks visible in approaching Chesapeake Bay entrance are described on page 110. From northward.-General remarks and directions for the outside coast from New York to Chesapeake Bay are given on page 31. Currents for the outside coast are described on page 25. From eastward.-The entrance may be approached boldly, as there are no outlying dangers. Twenty fathoms (36.5 m.) will be found about 45 miles eastward of Cape Henry; inside that depth the water shoals irregularly. In clear weather Chesapeake Lightship, 15 miles eastward of Cape Henry, should be picked up and the gas and whistling buoys followed to Chesapeake Bay. In thick weather vessels should keep outside the 10-fathom (18.3 m.) curve unless the lightship is sighted. In rough weather vessels of deepest draft should enter the bay through the channel about 3 miles off the shore south of Cape Henry. From southward.-Between Cape Henry and Cape Hatteras, a distance of about 105 miles, there are no dangerous outlying shoals over 5 miles from the beach; with the exception of a few places, 5 to 9 fathoms (9.1 to 16.4 m.) may be carried as close as 1 mile from the beach. Vessels of the deepest draft may, in smooth weather, run as close as 5 miles from the beach, but are not advised to do so, as it is a dangerous coast to be caught on in an easterly gale. The narrow stretch of sand beach forming the greater length of the coast is low and frequently may not be visible more than 4 or 5 miles. The 100-fathom (183 m.) curve, which, abreast of Cape Henry, is about 65 miles offshore, gradually approaches the coast southward, and southeastward of Cape Hatteras is only about 20 miles from the beach. The 30-fathom (55 m.) curve is about 5 miles inside of the 100-fathom (183 m.) curve. Abreast of Cape Henry 20 fathoms (36.5 m.) will be found about 45 miles off the coast, but farther southward that depth is found closer in, and at Cape Hatteras it is only 11 miles offshore. Inside of 15 fathoms (27.4 m.) the depths are extremely irregular, and there are many holes of limited extent lying far inside of the general limits of corresponding depth. In thick weather close attention should be paid to the soundings and the chart, and even then the navigator may be confused by the irregularities in depth. DIRECTIONS, CHESAPEAKE BAY Directions for entering Hampton Roads are given on page 122, and for Patapsco River and Baltimore Harbor on page 109. Directions from the head of Chesapeake Bay to Norfolk for vessels following the inside route are given on page 258. The least depth in the channel between Chesapeake Bay entrance and the entrance to the dredged channel leading to Baltimore is in the dredged channel eastward of York Spit, which is 35 feet (10.6 m.) deep and 1,000 feet wide. Between the entrance to the bay and this point the channel leads between Middle Ground Shoal and Tail of the Horseshoe and is well marked by buoys. Northward of York Spit the bay is clear in mid-channel, but shoals extend a long distance off many of the points and islands. Strangers, unless in small boats, should keep outside the buoys and lighthouses marking the ends of the shoals. The following table gives courses and distances from Chesapeake lightship, or entrance buoy No. 2 CB., to Baltimore. They lead in a least depth of 35 feet (10.6 m.). Between Tail of the Horseshoe gas and whistling buoy and Wolf Trap Lighthouse vessels of less than 20-feet (6.1 m.) draft often pass westward of York Spit channel. Many deviations from these courses are possible for light-draft vessels, but for these the chart is the guide. Chesapeake Bay Entrance to Baltimore [Abbreviations for lights: F., fixed; Fl., flashing; Gp., group; Occ., occulting; Alt., alternating; W., white; R., red; G., green. Color white unless otherwise indicated] Chesapeake Bay entrance to Baltimore-Continued Course True Magnetic Distance in nautical miles FROM CHESAPEAKE LIGHTSHIP-continued 6. To % mile westward of Tangier Island A 20-foot spot lies 0.85 mile, 14° true, from Tangier Shoal Lump gas and bell buoy, 12 TL, and is a menace to vessels passing close eastward of the buoy. 7. To 1 mile eastward of Smith Point Light (Fl.). 8. To close westward of Sharps Island gas and bell buoy, passing 11⁄2 miles eastward of Point No Point Light (Fl., Alt., W., and R.), and 1 mile eastward of Cove Point Light (Fl.). CHESAPEAKE BAY ENTRANCE [Chart 1222] The entrance to Chesapeake Bay leading between Cape Charles on the north and Cape Henry on the south is about 10 miles wide; the main channel leads along the south side and is broad and deep. The northern half of the entrance is obstructed by shoals through which several minor channels lead. The channel south of Nautilus Shoal and between Fisherman Island and Inner Middle Ground, and thence through either North or Beach Channel, had a depth by the last survey of 24 feet (7.3 m.), but with spots of 16 and 17 feet (4.8 and 5.1 m.) close to its southern side. The shoals on the north side have shifted southward and it has become necessary to add two more buoys to mark the channel Cape Henry Lighthouse (right) and Old Tower there. It is used by fish steamers and tugboats up to 12 feet (3.6 m.) draft, but is not recommended for strangers. The most prominent landmarks seen in approaching the entrance to Chesapeake Bay are Cape Charles Lighthouse and Cape Charles old tower on Smith Island, and a tank and several buildings on Fisherman Island, all on the north side; and Cape Henry, Cape Henry Lighthouse, Cape Henry old tower, and the Cavalier Hotel at Virginia Beach, on the south side. Cape Charles Lighthouse is described on page 86. Cape Henry is a prominent bold range of sand hills 80 feet (24.4 m.) high, with lower ones near the water. On the beach near the point of the cape is Cape Henry Lighthouse, and 340 feet southwestward of it is a white unused light tower; near the lighthouse are a storm-warning display station and a seacoast telegraph station of the United States Weather Bureau, from which vessels are reported to Norfolk and Baltimore, and with which they may communicate by the use of International code signals by day or the Morse code by night. |