Tugboat

Tractor, also called tugboats, (English or tugboat tug) are ships with powerful drive system, which are used to push or pull other ships or large buoyant objects. Most tow lines are used to draw that are mounted on the tractor to hook up or rolled up on winches. In Germany there are together with the pushing of barges 450 Pieces (2000 ).

Types of tugboats

Tractor can be distinguished on the design and purpose, the features can also overlap.

Distinction on the purpose

• Tug: seagoing tugs, which are used for the transport of sea-going barges, damaged ships or other objects.
• Anchor handling tug (AHT - Anchor Handling Tugs ): sea-going tugs with bollard pull high, which are used for entrainment of oil rigs; they are sometimes also as supplier for oil rigs ( AHTS - Anchor Handling Tugs Supply)
• Salvage Tug: seagoing tugs with bollard pull high, which are used for recovery of damaged ships; partly also in order of the State as a rescue tug in use
• Port, assistance or Bugsierschlepper: relatively small, highly manoeuvrable tractor, the larger ships maneuver in ports to the berth (ie, drag, push, press, etc.).
• River or inland tractor: not sea-going tug, the tow motorless barges and barges through canals and rivers. Some of the boats or barges were designated as tugboats.

Distinction on the type

Basically, (engine, transmission, shafting, propellers, rudder ) and tugboats can be differentiated with all-round controllable drive (propeller gondolas or Voith-Schneider drive ) between tractors with conventionally designed drive system. In the latter design, a distinction according to the installation position of the drive systems.

• Rear tractor ( ASD - Azimut Hing Stern Drive, dt swiveling rear-drive): One or two drive systems, installation in the rear
• Tractor tractor: One or two drive systems, installation under the foredeck
• "Rotor " tractor: three drive systems, two at the bow, another in the rear. The tractor can turn on the spot. The term " Rotortug " is a trademarked name of the Dutch company KST.

Performance, bollard pull, propeller characteristics

The performance of the tractor varies depending on the type. A key measure is the so -called bollard pull, which is measured in tonnes. Tug have engine power of 15,000 kW or more, the bollard pull can be over 250 tons. Modern larger Tug Boat develop a bollard pull of 20 to 80 tons in engine power from 2,000 kW to 4,000 kW.

The fact that a tractor has to apply a much greater thrust than its own resistance at the respective speed, means that its propeller must also have their optimum operating point at a relatively small progress digit. Therefore, the propellers of tugs are mostly designed as ducted propellers, ie they are encased in a Kort nozzle.

The most powerful anchor handling tug German shipping companies are the Uranus and Orcus the Hamburg company Harms salvage Transport & Heavy Lift GmbH & Co. KG, with a bollard pull of 285 tonnes, followed by Janus and Ursus ( per 219 tonnes ) of the same shipping company

Even the world's most powerful salvage tug for German shipping companies are in use. the Nordic used as rescue tug has a bollard pull of 201 tons, 180 tons of its predecessor Oceanic. Operations are or were both ships of the Hamburg ship-handling, shipping and salvage mbH & Co. KG.

Maneuverability

Tug Boat must be highly manoeuvrable due to the limited in the narrow harbor activity areas. Therefore be used for the drive in contrast to previous models with conventional drive systems often indefinitely around the vertical axis rotating propeller gondolas, called Schottel rudder propellers. These can be used as a main drive or as a primary Maneuvering.

Another variant is to be at the blade-like wings downward inserted through a sophisticated mechanism for driving Voith-Schneider drive. Tractor with this drive are also referred to as " Voith-Schneider tractor ."

Tow

In many cases, the tractor use is done not by bollard pull, but by direct pressure on the ship's hull, called the maneuver. This saves the line connection and makes maneuvering in a confined space, such as at docks. The hull of the ship maneuvered need for it to be particularly reinforced at appropriate locations to avoid deformation. The relevant points of the hull are marked accordingly, for example with the font Zung " TUG ". So Bugsierschlepper have (not to be confused with the ship-handling shipping company ) in addition to the usual rub rails large rubber buffer at the bow and depending on the drive system at the rear.

Rubber buffer on the bow of an old tractor in Brunsbuttel