Re: Hatch covers

From: Tom Hynes
Remote Name:
Date: 01/07/07
Time: 11:45 AM


I believe it has to do with two things: first, maintaining as much of the main deck area intact as possible for structural reasons and second, matching existing loading and unloading equipment who's history goes back to 1859. Iron ore was first shipped on the lakes in 1852 from Marquette. (3 years before there were even locks at the Soo, so it had to be unloaded and transported across land there.) It was first loaded in barrels, but after the locks opened it was loaded in bulk using wheelbarrels. By 1859 the first gravity pocket dock was built in Marquette. Railroad cars were pushed out onto the dock and dumped by gravity into holding bins or pockets. Once a ship was available it was dumped out of pocket into the ships hold using a long chute so it could reach the center of the ship. The railroad cars being used at the time were 12 foot (3.7m) long, 4 wheel cars. At that time, sailing vessels were carrying most of the ore. The first steam powered bulk carrier was the R.J Hackett that was built in 1869. Because of the length of the railroad cars then in use, the pockets were spaced at 12 feet as well. Later, 24 foot (7.3m) 8 wheeled cars came into use are are still the standard cars used today to serve all the U.S. ore loading ports on the Great Lakes. Most of the docks maintained a 12 foot pocket spacing with a single cut of railroad cars filling every other pocket. Another cut would be brought onto the dock to fill the remaining pockets. Up to 75 different iron ore grades/subgrades were mined and they were often blended on the dock, using the pockets and the ships holds to combine different ores. Anyway, the ships evolved into having their hatches on either 12 or 24 foot centers to match the spacing of the ore dock pockets.(there are a few boats with hatches on 48 foot centers) Most boats have 4 to 7 holds, with 2 to 6 hatches per hold. For example the Wilfred Sykes has 6 holds, with 3,3,4,3,3,and 2 hatches per hold respectivly. The hatches are 44 feet wide and 11 feet long. It is 678'(overall) x 70' x 37' or 206m x 21.3m x 11.3m. Here are some links to a few photos that show the current dock at Marquette. Railcar length and hatch spacing are 24 feet, while pocket spacing is 12 feet. There is also a photo inside the hold of a self unloader.

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