Towboat engine outputs range from less than up to . Most towboats are from long, and wide. Smaller boats are used in
harbors, fleeting areas and around
locks while larger boats operate in "line-haul" operations over long distances and between major ports. In the United States, south of the
Chain of Rocks Lock across from
St. Louis on the
Mississippi River, the river is open with no locks or impediments other than channel size and depth. Larger boats can run this segment of the river with the maximum tow size of 42 barges southbound and 40+ northbound. A typical River tow might be 35 to 42 barges, each about long by wide, configured in a rectangular shape 6 to 7 barges long and 5 to 6 barges wide, depending on the number of barges in tow. The whole tow, excluding the towboat, can easily be over long and wide, covering over and holding thousands of tons of cargo. In the United States above St. Louis on the Upper Mississippi River and on other rivers such as the
Illinois,
Ohio,
Arkansas,
Tennessee and
Cumberland, boats can handle only up to 16 barges including a "hip" barge due to the size of lock chambers. These boats tend to be limited to . Towboats in line-haul service operate 24/7 and have the latest in navigational equipment, such as color radar, GPS systems, electronic river charts, and specialized radio communications. at Louisville, Kentucky Boats that traverse the Intracoastal Waterway (ICW) are commonly referred to as "ditch boats" or "canal boats". ICW tows usually consist of 1 to 6 barges ranging in size, usually "strung out" end to end when loaded or "breasted up" side by side when empty. Towboats always push the "tow" of barges, which are lashed together with steel cables usually in diameter. ==History==