UMD researchers reveal data from wetland studies in the Northland
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2 | The shipsThe largest ships that visit Great Lakes ports are designed to carry such bulk cargoes as iron ore, coal, stone and grain. Other ships are designed for general cargoes such as machinery, steel and bagged food products. Still others are more specialized as tug and work boats, commercial fishing vessels, tankers, day excursion boats, and railroad car ferries, among others.
Most all of the U.S. vessels in the current fleet were built as self-unloaders, equipped so the crew can unload the vessel without any need for shoreside personnel or equipment. Most have a pivoting boom with conveyor; others have a system near the stern that telescopes out. Numerous other vessels on the lakes have been converted from a straight-deck design to self-unloaders. The largest of the Great Lakes self-unloading bulk freighters are 1,000 feet long, but range upward from 500 feet. Self-unloading equipment and enormous cargo capacity make them very efficient carriers. Invented on the Great Lakes, the self-unloading technology allows a 1,000-foot vessel to routinely discharge as much as 70,000 tons of iron ore or coal in less than 10 hours! The vessels are diesel powered with speeds up to 15 knots. Crew size ranges from 21 to 27, similar to other Great Lakes carriers. The Frontenac, a self-unloader owned by Canada Steamship Lines, and the Walter J. McCarthy Jr., owned by the American Steamship Company, are two frequently seen self-unloaders on the Great Lakes.
The J.A.W. Iglehart, pictured at right, was converted in 1965 from an ocean-going tanker to a self-unloading cement carrier. She became the last saltie-to-laker conversion on the American side.
The other type of laker, the straight-deck bulk carrier (or straight-decker), is designed to carry up to 30,000 tons of coal, grain, ore, stone and other dry bulk cargoes. Ranging in length from 600 to 800 feet, these lakers do not have the special self-unloading rig above deck. With diesel or turbine power, their average speeds are from 12 to 16 knots. The crews number up to 27.
Most ships on the Great Lakes are owned by private companies, either Canadian or American. These ships can be distinguished by their hull colors and smoke stack markings. Overall, more than 150 fleets can be identified by the special markings on the stacks of their ships. Several insignia date back more than a century. Many are made up of common geometric shapes in combination with colored bands and initial letters while a few use corporate logos or other unique symbols. One might expect to see an initial "B" on Bethlehem Steel's insignia, pictured at left. Instead, one of the firm's products, an I-beam, is symbolized.
Ships registered in more than 60 countries visit Great Lakes ports annually. More than 800 ocean vessels transit the Great Lakes each season bound for American or Canadian harbors. Each of these vessels flies at the stern the ensign or national flag of the country in which it is registered. The port of registry is usually painted across the ship's stern below its name. At the bow, ships may also fly the national flag of the host port they are visiting.
Whistle blasts...what do they mean?
2 short: Ship ready to secure
1 long every 2 minutes: Vessel moving in fog
1 long and 2 short: Master salute
5 short quick blasts: Danger
Graphics: The Frontenac, the Walter J. McCarthy Jr. and the J.A.W. Iglehard, all shown at the Port of Duluth-Superior; the tug-barge Pathfinder; two foreign-flag vessels in Illinois' Calumet Sag Channel; Bethlehem Steel stack insignia courtesy Great Lakes and Seaway Shipping.