tug boat 101 near coastal and ocean service

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Homeland Security Tug Boat 101

Near Coastal and Ocean Service

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Performance Objective

Identify towing vessel types and their associated services near coastal and ocean services including Hawser, Wire,

and ATB/ ITB’s.

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Near Coastal

Ocean waters not more than 200 miles off shore.

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Oceans

The waters seaward of the Boundary Lines.

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Homeland Security HAWSER BOAT

Tugboats that use lines to make tow are known as hawser boats.  They are still used today on bays and rivers for towing barges of general cargo. 

A simple, but labor intensive towing technique. No towing winch and the related machinery is necessary.

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The hawser is usually a full coil (600 feet) of nylon line, sometimes more. 

Traditional looking three strand line can be used but most use plaited line. The image below shows the line

faked out on a stern rack.

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Putting a barge on tow or “Stringing” out the tow

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Hawser Tug made up in the notch of tow

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Homeland Security HIP TOW &TOWING

ALONGSIDE

• A hip tow can be made up on either the port or starboard side of the tug.

• Hawser Boats will also move other vessel on the hip

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TOWING VESSELS OPERATING IN THE HARBOR

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Ship Docking

• A tug positioned at the bow of the ship it is moving.  This is the most common job of the ship docking tug in harbors.

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Ship Docking

• Small tug with a line up on the stern of a ship.  Sometimes harbor tugs are employed this way to help a ship steer while transiting winding rivers. 

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Tractor type tug assisting in ship maneuvering

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Propulsion methods unique to ship handling

• Schottel / Z-Drive

•Voith Schneider

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Z DRIVE

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Schottel Video

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VOITH SCHNEIDER PROPELLER

• Also known as a cycloidal drive. It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries. Voith Operation Video

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Homeland Security TOWING VESSELS

OPERATING OFFSHORE - WIRE BOATS

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Homeland Security Wire Boat

Towing Winch

The towing winch has one or two drums of cable. 

Most winches have a capstan built on and controlled by the winch station. 

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Homeland Security Wire Boat

The after steering station

The vessel can be operated from this location when necessary. The winch controls are also contained on the console. 

Sometimes this console is in a protected booth called the dog house.

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Wire Boat

Depending on where the boat is from, this is a Texas bar or a Dutch bar. 

The two wheels in the middle there are called doughnuts and they can slide separately the entire length of the bar. 

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Wire Boat

These rollers on the stern of this tug are able to be retracted. 

With one roller up, the cable is steered into the center of the stern as described before and then the second roller is raised up to hold the cable to the middle of the stern rail.

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Wire Boat

Here is a shot of the cable in place between the rollers.  You'll notice a piece of pipe has been used for chafing gear. 

This kind of gear is made by cutting a section, length-wise out of a two or three foot long pipe.  The slot allows the cable to slip into the pipe.

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Wire Boat

Here is another shot of a towing cable over the stern with no roller system. 

The chafing gear can be seen more clearly and a hogging line has been added to hold the cable more firmly in place.

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Catenary

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ARTICULATED/ INTEGRATED

TUG AND BARGE COUPLINGS

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Defining The Terms

Articulate

• To put together with joints

Integrate

• To make whole or complete by adding or bringing together parts

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Homeland Security ARTICULATED UNITS

ATBs are referred to as “Dual-Mode ITB” in NVIC 2-81:

• The tug is mechanically connected to the barge but is free to pitch independent of the barge in a seaway.

• These units typically work with the tug in the notch but can decouple at any time the Captain or Chief Engineer see fit due to operational requirements and the tug then tows the barges on an emergency hawser.

• Some suppliers of connection systems used in the ATB industry are:

InterconJAKBludworth

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Homeland Security ATB

• The JAK Coupling connection system is widely used on ATBs.

• The system uses connection pins on each side of the tug, operated pneumatically, secure the tug to the barge and can be released in less than a minute.

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Homeland Security ATB

• The Intercon connection system may be the most used connection system on ATBs.

• The system uses connection pins on each side of the tug are operated by high pressure hydraulics that secure the tug to the barge and can be released in less than a minute.

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ATB

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Homeland Security INTEGRATED UNITS

• ITB’s are referred to as “Pushing Mode ITB” in NVIC 2-81

• These are the units that maintain connection at all times during operation except, emergencies. The tug is rigidly connected to the barge and act as one unit. There are few, if any, still in operation and are generally treated as ships.

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Questions?

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