Tugboats
A tugboat, or tug, is a boat used to maneuver, primarily by towing or pushing, other vessels in harbours, over the open sea or through rivers and canals. They are also used to tow barges, disabled ships, or other equipment like towboats.A tugboat is a small, strongly built vessel, used to guide large oceangoing ships into and out of port and to tow barges, dredging and salvage equipment, and disabled vessels. Tugboats are quite strong for their size. Early tugboats had steam engines; today diesel engines are used. Tugboat engines typically produce 750 to 3000 horsepower (500 to 2000 kW), but larger boats (used in deep waters) can have power ratings up to 25 000 hp (20 000 kW). The engines are often the same as those used in railroad engines, but typically drive the propeller mechanically instead of converting the engine output to power electric motors, as is common for railroad engines. For safety, tugboats' engines feature two of each critical part for redundancy. Most tugs are built of wood or metal-sheathed wood; the resiliency of a wooden hull prevents damage to both tugboat and vessel in berthing operations.
There are two groups of tugboats, either Inland or Oceangoing. Inland tugboats come in two categories. The first is the Harbor tugs which are the most typical of the tugboats that people recognize. They are used worldwide to move ships in and out of berth and to move industrial barges around waterfront business complexes. The second type of Inland tugboats is the River tugs which are also referred to as towboats or push boats. They are designed as large squared off vessels with flat bows for connecting with the rectangular stern of the barges. They are capable of pushing huge fleets of barges that are lashed together into "tows". Some tows can be up to 1000 feet long and 200 feet wide. Despite their size, they are designed to push their tow rather than tow from the stern.
Oceangoing tugboats come in three categories. The conventional tug is the standard seagoing tugboat with a model bow that tows its payload on a hawser. It operates independently and is used to tow various loads, e.g., cargo barges, ships, oil rigs, and etc. They are importantly recognized as the design of choice for salvage and assistance of wrecked ships and in the rescue and safe return of disabled ships from the high seas. The notch tug is a conventional tug which is assigned to tow and push a specific barge, usually built to the shape and specifications of that tugboat. A notch tug has a large towing winch on its stern but it gets its name from the deep notch built into the stern of the barge. In the event that the seas get too rough to push safely, the tug merely releases any securing lines and backs out of the notch while extending its towing hawser. The articulated tug and barge, or ATB, is a specially designed vessel, comprised of a tugboat and a barge which are coupled using specially designed machinery. The tug is connected to the barge inside a notch, similar to the notch boat, using a system of heavy pins, clamps, and/or side pads. ATB's remain coupled all the time; the tug pushes its barge in all but the roughest seas.
www.heavyloadtrade.com
