458 ¢ U.S. Coast Pilot 6, Chapter 13 Chapter 6, Pilot Coast U.S. 88°W 86°W Chart Coverage in Coast Pilot 6—Chapter 13 NOAA’s Online Interactive Chart Catalog has complete chart coverage 2312 http://www.charts.noaa.gov/InteractiveCatalog/nrnc.shtml NIPIGON BAY 92°W 90°W BLACK BAY 2304 State Islands ONTARIO 14968 THUNDER 2303 under Bay BAY 2313 2308 a l e 14976 2309 14967 R o y 48°N I s l e CANADA Grand Marais UNITED ST Michipicoten Island MINNESOTA 14964 ATES Taconite Harbor L AKE SUPERIOR 2307 14972 14966 Hancock 2310 A Y Two Harbors Apostle Islands Houghton B A W N 47°N E E W E Duluth K Ontonagon 14975 Port Wing 14971 14970 Superior 14974 14969 Grand Marais Ashland Marquette WHITEFISH BAY 14965 14963 14884 Munising 14962 WISCONSIN MICHIGAN 46°N 19 SEP2021 19 SEP 2021 U.S. Coast Pilot 6, Chapter 13 ¢ 459 Lake Superior (1) and fall; the lowest stage is usually reached at about the Chart Datum, Lake Superior close of winter and the highest during the late summer. (14) In addition to the normal seasonal fluctuation, (2) Depths and vertical clearances under overhead cables oscillations of irregular amount and duration are also and bridges given in this chapter are referred to Low Water produced by storms. Winds and barometric pressure Datum, which for Lake Superior is an elevation 601.1 feet changes that accompany squalls can produce fluctuations (183.2 meters) above mean water level at Rimouski, QC, that last at the most a few hours. A storm of this type on International Great Lake Datum 1985 (IGLD 1985). in 1939 produced fluctuations at Marquette with a (See Chart Datum, Great Lakes System, indexed as maximum range of 7.4 feet. At other times, strong winds such, chapter 3.) of sustained speed and direction can produce fluctuations (3) that last a few hours or a day. These winds drive forward a greater volume of surface water than can be carried Lake Superior Dimensions off by the lower return currents, thus raising the water Description Length/Area level on the lee shore and lowering it on the windward Duluth Ship Canal to Point Iroquois 383 miles shore. Fluctuations caused by such winds seldom exceed (steamer track) 1 foot above or below the normal level, but may cause Duluth Ship Canal to Michipicoten 350 miles Harbor changes up to 2 feet. An unusually severe storm in 1905 Breadth at longitude 86°45'N 160 miles temporarily raised the water level in Duluth by 2.3 feet. (15) Through an agreement between the United States Maximum recorded depth 1,333 feet and Canada, the water level of Lake Superior is controlled Water surface (including St. Marys 20,600 sq mi (U.S) River above Brush Point) 11,100 sg mi (Canada) by means of compensating works in St. Marys River. The Drainage basin (including St. Marys 37,500 sq mi (U.S.) dikes and sluice gates in the river are operated so as to River above Brush Point) 43,500 sq mi (Canada) maintain the monthly mean level of Lake Superior as nearly as possible between elevations 599.61 feet (182.76 meters) and 603.22 feet (183.86 meters) above the mean (4) General description water level at Rimouski, QC, on International Great Lakes Datum 1985 (IGLD 1985). (5) Lake Superior, the largest freshwater lake in the world, is the northernmost, westernmost, highest and (16) deepest of the five Great Lakes. The lake is fed by the Weather, Lake Superior waters of many short swift-flowing streams and drains (17) Strong winds are a threat from fall through spring through the St. Marys River into Lake Huron. The shores over the open waters. Late autumn is the worst, when of the lake are generally high, rocky and forested. The gales blow up to 6 percent of the time. The west part of lake is sparsely populated, especially along the north the lake is least susceptible since it is somewhat sheltered shore. from the strong winds, many of which have a westerly (6) The waters of Lake Superior are colder and form or northerly component. Fall windspeeds of 28 knots or more shore ice than do the other lakes. The navigation more occur 11 percent of the time in this region compared season, shorter than the other lakes, is generally about 8 to 16 to 18 percent elsewhere. months long. The actual length of the season depends (18) Spring winds are variable, with north through primarily on whether tonnage demands justify the expense southeast winds common in the morning; southwesterlies of ice breaking for earlier or later vessel movements. also appear in the west. Afternoon directions are similar, Commercial fishing operations from harbors around the with the addition of northwesterlies in the east. Gale lake continue throughout the year except where prevented frequencies drop to 2 percent or less by May; however, by ice conditions. some of the highest winds of the year are encountered during this season. Along the shore, it is a volatile time. At many locations, April registers the highest mean (12) Fluctuations of water level windspeed of the year, while speeds of 28 knots or more also reach a peak. At Duluth, they blow up to 3 percent of (13) The normal elevation of the lake surface varies irregularly from year to year. During the course of each the time in April, a month in which its highest windspeed year, the surface is subject to a consistent seasonal rise of 65 knots (northeast) was recorded. Marquette recorded 460 ¢ U.S. Coast Pilot 6, Chapter 13 19 SEP 2021 (7) Recommended Courses on Lake Superior Downbound/Outbound The Lake Carriers’ Association and the Canadian Shipowners Association have recommended the following courses for downbound/outbound and upbound/inbound traffi c in Lake Erie. These courses are recommended and recognized for the Great Lakes by both Associations, with navigation safety and application of the Collision Regulations always taking priority. While strict observance of these courses is recommended for all Masters, Navigating Offi cers of the Watch, and Pilots for their respective vessels in the interest of navigation safety, these are recommended and voluntary lake courses. They are delineated on general and other charts of the Great Lakes both in paper and electronic formats. The distances given for these courses are given in statute miles with the nautical mile equivalents shown in parentheses. To Upper St. Marys River from: Duluth • From a departure position bearing 063° at 3.0 (2.6) miles from the outer end of the Duluth Piers, steer 063° for 69.0 (60.0) miles to a point 12.0 (10.4) miles due north of Devils Island Light. • From this point, steer 077° for 123.1 (106.9) miles to a point 12.0 (10.4) miles due north of Eagle Harbor Light, then steer 085° for 14.0 (12.2) miles to a point 12.0 (10.4) miles due north of Copper Harbor Light. • From here, steer 105° for 18.3 (15.9) miles until Manitou Light bears 204° at 12.0 (10.4) miles, then steer 114° for 131.4 (113.8) miles until Whitefi sh Point Light bears 210° at 2.5 (2.2) miles. • From here, steer 147° for 14.8 (12.9) miles until Ile Parisienne Light bears 050° at 2.5 (2.2) miles, then steer 138° for 9.8 (8.5) miles until Gros Cap Reefs Light bears 113° at 0.6 (0.5) mile. Thunder Bay • From a departure position south of Welcome Island, steer 118° for 8.9 (7.7) miles until Thunder Cape Light bears 047° at 2.5 (2.2) miles or from a departure position 0.5 (0.4) mile northeast of Welcome Island Light, steer 137° for 9.1 (7.9) miles until Thunder Cape Light bears 047° at 2.5 (2.2) miles. • From this point, steer 097° for 26.1 (22.7) miles until Blake Point Light bears 188° at 2.5 (2.2) miles, then steer 121° for 2.1 (1.8) miles until Passage Island Light bears 030° at 1.0 (0.9) mile. • From here, steer 148° for 15.0 (13.0) miles until Passage Island Light bears 330° at 15.5 (13.5) miles, then steer 118° until Whitefi sh Point Light bears 210° at 2.5 (2.2) miles. • From this point, steer 147° for 14.8 (12.9) miles until Ile Parisienne Light bears 050° at 2.5 (2.2) miles, then steer 138° for 9.8 (8.5) miles until Gros Cap Reefs Light bears 113° at 0.6 (0.5) mile. Marquette • From a departure position 2.0 (1.7) miles east of Presque Isle Harbor Breakwater Light, steer 076° for 58.3 (50.7) miles to a point 7.0 (6.1) miles due north of Au Sable Light, then steer 082° for 48.5 (42.1) miles until Whitefi sh Point Light bears 128° at 10.0 (8.7) miles. • From here, steer 114° for 10.0 (8.7) miles until Whitefi sh Point Light bears 210° at 2.5 (2.2) miles, then steer 147° for 14.8 (12.9) miles until Ile Parisienne Light bears 050° at 2.5 (2.2) miles, and then steer 138° for 9.8 (8.5) miles until Gros Cap Reefs Light bears 113° at 0.6 (0.5) mile. Superior • From a departure position with Superior Entry South Breakwater Light bearing 235° at 2.0 (1.7) miles, steer 044° for 17.7 (15.4) miles to a point 3.8 (3.3) miles southeast of Knife River Harbor Entrance Light, then steer 063° for 52.1 (45.3) miles to a point 12.0 (10.4) miles due north of Devils Island Light.