At BNSF#5 they use a multibelt system, loading 12 hatches at once. Then we shift back or forward 24 feet and load the other 12. Thats where the speed comes in. You better have a good engineer and QMED on the pumps because at that rate you can barely keep up with the de-ballasting! Actually, at that dock, we would often have to take a ballast delay after the second run, to strip the water out before we started the trim.
The ship loaders at Duluth CN Dock ( old D.M.and I.R. dock) and at Two Harbors ( also owned by Canadian National Railroad) are also multibelt systems and are very efficient. Delays come in when we follow a ship taking a differant blend of ore so the dock has to purge and restock before loading us.
The stone docks at Port Inland, Calcite,Cedarville, Stoneport, Drummond Island, and Meldrum Bay are single belt loaders. Some travel on tracks, others the ship has to shift every hatch. We load limestone at Port Inland, and Cedarville. Limestone loads go to a shallower dock so we take 26000 G.T. normally. That takes 10-12 hours as well. Usually 2000-3000 tons per hour average.
On the Great Lakes, at least with this company, we are normally in a loading or unloading port every day, unless we have a run up to the Lakehead at Duluth. Then things stretch out a bit. We HAVE taken on occasional single belt cargos of odd cargos like slag or mill scale out the Seaway that took 3-4 days to load, so maybe thats what the other guys are talking about. Iron ore and stone have become such a specialized cargo around here that they really move it.
In Escanaba, many companies use the docks but they are almost exclusively bulk carriers bringing in stone or coal and taking out iron ore. The town is a beautiful spot,with no industry around it, just a railhead and a loading dock. There is a small shipyard that gets business from tugs, fishingboats and small Coast Guard vessels. People are friendly, the local women like sailors, and there is a micro brewery that makes a great beer called “White-Tail Ale”.