The currents of Lakes Michigan and Huron / John C. Ayers.

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current and are run by it as a large gear would run three small gears.
Currents in the west-central part of the southern half of the lake appear
to be weak, except from Michigan City northward to the offing of Waukegan.
In the northern half of the lake (in Chart 3) the dominant feature is the
outflow current which passes up the Michigan shore from Big Sable Point past
Point Betsie and the Manitou Islands almost to Seul Choix Point on Michigan's
Upper Peninsula. Off Seul Choix Point the current divides, with the larger
portion making a U-shaped swing southward to pass below Beaver Island and
approach the Straits of Mackinac from the southwest, and the smaller portion
passing eastward above the Beaver Islands to the straits. The outflow current
runs small clockwise eddies in the embayments between Big Sable Point and
Point Betsie, between Point Betsie and Sleeping Bear Point, in Little Traverse
Bay, and in Sturgeon Bay (Michigan). It also drives counterclockwise eddies
situated off Naubinway, Port Inland, and Manistique on the Upper Peninsula of
Michigan.
On the west side of the northern part of the lake the currents tend to be
southward with the outflow from Green Bay contributing part of the alongshore
flow. A large counterclockwise eddy lies in the east-central part of the lake
off Frankfort.
The Straits of Mackinac
Under prevailing winds the surface current in the Straits is to the east
with division of the'&flow after it has passed Point Mackinaw. The major part
of the current passes down South Channel, for prevailing winds are from the
north of west. Minor portions of the current pass between Mackinac Island
and Round Island; current speeds in this pass may be high as a result of the
narrowness of the channel. Prevailing winds usually cause southward current
between Mackinac Island and St. Ignace.
Lake Huron
Chart 5 shows the surface current pattern of Lake Huron on 29 June 1954.
Three multiple-vessel single-day coverages of the lake were made during the
summer of 1954; of the three the one shown is the most "normal." Chart 20
shows the courses of the vessels and the stations they visited. Winds prior
to this coverage (Table 2) were more consistently from the prevailing directions than was true in the days before the other two. Further, the results
shown in Chart 5 are confirmed by two previous all-shipping-season-long
studies of currents which gave the same main current features but did not
cover the lake so completely.
There are two primary features in the Lake Huron current pattern: the
flow-through current and the mid-lake eddy. The flow-through current is the
belt of main current by which the inflows from Lakes Michigan and Superior
pass along the length of the lake and arrive at the St. Clair River. The midlake eddy is a large counterclockwise eddy of current located in about midlake between Presque Isle and Cape Hurd. As was the case in Lake Michigan,
smaller eddies are associated with, and driven by, both the primary current
features.
The flow-through current originates in the eastern part of the Straits of
Mackinac. Lake Superior water emerging into Lake Huron through Mississagi