Tugs engaged in pushing barges on U.S. inland waterways are almost universally referred to a towboats rather than tugs. A towboat is a river vessel designed primarily to push barges and the like; actually she is a "pushboat" but is never called so. A tow is one or more barges or other floating vessels in charge of a self-propelled vessel which has undertaken to transport such responsibility elsewhere. A tow is made up when it has been hitched together and made ready for moving. A barge moored to the front of a towing vessel is the towbarge and the ones out front are the lead barges. When a barge is towed alongside a towboat it is "slung under her arm" or "on the hip." When pulled behind, the barges are said to be "railroaded." When loosely coupled behind, it is called a "mule train."
US inland towboats have nearly rectangular waterplanes with low freeboard. The bows are fitted with push knees, flat steel frames, faced with timber or heavy rubber pads, which provide a flush mating surface between the tug and barge. Cables used to secure the towboat to the barge are known as facewires, and are normally made up on winches located amidships or further aft on the towboat. Double push knees are preferable to a single knee as there is less strain on the facewires. Push knees are to a towboat what towing bitts are to an oceangoing tug; thrust developed by the tug is focused at this point.
The domestic US marine fleet numbers more than 30,000 tugboats, towboats, and barges. The US has 41,009 km of waterways, with 19,312 km used for commerce. The Saint Lawrence Seaway of 3,769 km, including the Saint Lawrence River of 3,058 km, is shared with Canada. The U.S. tugboat, towboat, and barge industry, a vital segment of America's transportation system. The industry safely and efficiently moves over 800 million tons of cargo each year, including more than 60 percent of U.S. export corn, more than 50 percent of U.S. export grain, energy sources such as coal and petroleum, including most of New England's home heating oil and gasoline, and other bulk commodities that are the building blocks of the U.S. economy. The fleet consists of nearly 4,000 tugboats and towboats, and over 27,000 barges of all types. These vessels transit 25,000 miles of inland and intracoastal waterways, the Great Lakes, and the Atlantic, Pacific, and Gulf coasts. The tugboat, towboat, and barge industry provides the nation with a safe, secure, low-cost, environmentally-friendly means of transportation for America's domestic commerce.
There are many different styles of towboats, small and large, on the river. Many have traveled great distances, some are local. Towboats on the Upper Mississippi are usually 3,000 to 5,000 horsepower, and south of St. Louis the boats are larger because they are allowed to push more barges. The river becomes deeper and wider below St. Louis.
The M/V Mississippi is the Corps of Enginers' flagship and the largest towboat in America. The Rock Island District of the U.S. Army Corps of Engineers Motor Vessel (M/V) Mississippi is one of the largest towboats ever built in the United States, the M/V Mississippi. The 52-foot tall vessel is primarily a working towboat that weights 2,600 tons and is powered by three Caterpillar 3,606 diesel engines and three generators. The vessel is 241 feet long and holds 80,235 gallons of fuel. It visits the Upper Mississippi River once a year. Its homeport is Memphis, Tenn. The towboat, built in 1993, is the fifth Corps vessel carrying the M/V Mississippi name. The first, built for the Mississippi River Commission in 1882, was a steamer. The fourth was the first diesel-powered vessel to carry the name. The current Mississippi has a crew of 37 and works about eight months a year. Today's Motor Vessel Mississippi, like her predecessors, serves a dual function. She serves as an inspection vessel for the Mississippi River Commission each spring and fall. The commission conducts a series of public meetings aboard the vessel at various river communities. It also serves as a towboat during the revetment season (mid July to the end of November). It is responsible for the movement of a variety of floating plant and barge loads of articulated concrete mattress in association with revetment operations.
Towboats hold a crew that must live aboard for extended periods of time. How comfortable they are depends on how long you are aboard, the roommate situation, and what comforts of home they are accustomed too. There are bathrooms, a living room, galley, dining room, laundry room, and bedrooms. The chances of getting a single bedroom on board seems to get better as your salary increases. The hard working crew consists of around 10, captain, pilot, first mate, engineer, cook, and about 5 deckhands. They work six hours on and six hours off, keeping the boat going 24 hours a day, rain or shine, day or night. No days off are allowed until they get off the boat. The typical crew works 30 days on and 30 days off. Many crews feel the best part of the job is the adventure and scenery of the river.
In the absence of significant wave action, the best position for a towboat is at the barge stern (Churchward et al. 1981). While the main factor in selecting a towboat is its ability to maneuver and push or tow the barges, the towboat's draft is also an important factor. The towboat draft should be consistent with site and transport route water depths to prevent sediment resuspension from propwash and hull dragging. Towboats are also used to move the dredge floating plant (when not self-propelled).
Although grain- or coal-filled barges are typically moved in large, integrated tows (up to 40 barges), dredged material-filled barges are generally hauled individually. A typical maintenance dredging operation might use two barges (one is filled by the dredge while the other is being transported to or from the disposal or rehandling site). If the distance between the dredging and disposal or rehandling site is long, additional barges and towboats may be used. The objective is to have sufficient barges and towboats available to keep the dredge operating continuously.
Barges are arranged in longitudinal rows called strings; the string directly ahead of the towboat is the push string; those outboard are drag strings. River width and turns limit the size of both tow and towboat. The tows of seagoing barges when navigating the inland waters of the United States shall be limited in length to five vessels, including the towing vessel or vessels. Tows on the rivers above Pittsburgh seldom consist of more than 6 barges, handled by 60- to 90-foot towboats of 800 to 1,500 horsepower. On the Ohio and upper Mississippi, tows may consist of 12 to 15 barges handled by 160-foot towboats of 3,000 to 4,000 horsepower. On the lower Mississippi, tows of 40 to 60 barges are handled by towboats of 8,000 to 10,000 horsepower.
Barges moving on the Mississippi River System normally have a draft of 9 feet, a width of 35 feet, and a length of 195 feet. Usually barge configuration on the Upper Mississippi River System (UMRS) consists of a system of 5 barges tied together and moving 3 abreast. This results in a planform surface area of 975 square feet. Average speed of the barges varies from about 3.5 mph to about 11 mph.
Each year, more than 260 million tons of cargo move across the 2400 miles of the Ohio River system. The river is economically attractive as an alternative to rail and highway transportation of heavy bulk cargo such as coal, grains, and building materials if travel times are reasonable. However, as travel times increase because of congestion at the river's locks, the additional cost of operating a tow boat and barges cuts into the transportation savings.
The barge industry has benefited greatly from this Federal investment in waterways. Barges, which operate in a highly competitive industry characterized by very low barriers to entry, transport over half of domestically produced grains and oilseeds destined for export, about 67.6 million tons in 1995. Barge transportation is less important in the domestic grain and oilseed market, accounting for about 6 million tons or 3 percent of domestic shipments. Altogether, barge transportation accounted for about 19 percent of all grain and oilseed shipments in 1995, a ratio largely unchanged since the late 1970s.
Coal is transported by railroads, barges, trucks, overland belts, and slurry pipelines. The dominant form of coal transportation on a national basis is railroads, which account for about 62% of all coal movement. In 1999, coal accounted for 41% of all freight tonnage moved by U.S. rail carriers. Barges carry about 14% of all coal that is distributed in the U.S. while trucks haul about 12%. The remaining 12% is carried by Great Lakes and tidewater barges, conveyors and slurry pipelines. On a regional basis, barges and trucks take on a more important role. For example, in the Middle Atlantic and East South Central regions, which have access to river transportation on the Ohio and Mississippi rivers, barges account for about one-quarter and one-third of coal shipments, respectively.
Barge transportation is most important in the export corn and export soybean markets, where it accounted for 58 percent and 66 percent of shipments in 1995. Most corn and soybeans are grown near the Mississippi River system. Barge transportation is also important in the barley, rye, wheat, and sorghum export markets.
Less grain moved on the Mississippi River in 2005 than in any year since record keeping began in 1988. Grain barges moved 33.4 million tons in 2005, a 22 percent decrease from the 5-year average. Although hurricane-related damage to Mississippi River ports accounts for much of the decline in 2005, the decline began in 2003. One reason for the drop in barged grain has been increased movement of non-grain commodities-such as imported steel-in covered barges. Barge companies have been expanding barge routes in order to ship a growing volume of non-grain cargo from New Orleans to inland destinations. The extra revenue is welcomed by barge companies, but decreases the availability of barges for grain shippers and raises rates. During 2005, the competition for barge services, coupled with low water conditions and escalating fuel costs, caused an unprecedented surge in barge rates.
Another reason for the decrease in the volume of barged grain is that fewer new barges are being built to replace old barges that are retired, reducing the size of the fleet. Overall, barge demand is expected to remain strong for 2006 as non-grain commodities and grain compete for a smaller fleet of barges. Although some new barges are being built and put into service, the barge industry is concerned about overbuilding the fleet. Should the industry build too many barges, it would return to a situation where supply exceeds demand and rate reductions would result in inadequate returns on investment. In the short term, over-production of new barges is unlikely given the current high cost of steel and limited capacity of barge manufacturers.
In addition to the need for new barges, the barge industry is concerned about the deteriorating condition of the nation's inland waterways. About 53 percent of the locks and dams operated by the U.S. Army Corps of Engineers are older than their 50 year design life. Continued maintenance delays have caused infrastructure failures that have halted or delayed traffic at many locks. According to the Inland Waterways Users Board (IWUB) "additional Federal General Treasury revenues should be appropriated for the Civil Works program over the next several years to reduce the large maintenance backlog." While the Corps received a higher level of funding for FY2006, multi-year increases are needed. The IWUB is composed of 11 members from the barge industry. The IWUB makes recommendations to Congress regarding construction and major rehabilitation investments and spending levels on the commercial navigation features of the inland waterways system.
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