Towboats range in size from horsepower ( kW) up to over horsepower ( kW). Most towboats can vary in length from feet ( m) to feet ( m), and vary in width from feet ( m) to feet ( m) wide. Smaller boats are used in harbours, fleeting areas and around locks while larger boats operate in "line-haul" operations and inter-city routes. In the United States below St. Louis on the Lower Mississippi river, the river is open with no locks or impediments other than channel size and depth. So larger boats run this segment of the river with the maximum tow size of 42 barges southbound and 40+ northbound. A "box", so called due to the shape is feet ( m) x feet ( m), a "rake", so called due to the raked bow end, is feet ( m) x feet ( m). so 40 barges would be over feet ( m) long and occupy ove