Petroleum and Chemical Transportation

Articulated Tug Barges (ATBs)

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Crowley has proven itself as an innovator and leader in petroleum and chemical transportation through the development of an unrivaled articulated tug-barge (ATB) fleet which includes the newest and most sophisticated U.S.-flagged ATBs. Crowley’s innovative and industry leading ATBs are the result of years of research, testing and partnering with customers, all of which have helped design and build vessels that provide an innovative, environmentally friendly solution to the world’s petroleum transportation needs.

Our vessels differ from many competitors’ in that they are designed to operate and perform at service speeds of up to 12 knots (550 and 650 class) – performance not seen in ATBs prior to Crowley.  Additionally, Crowley’s ATBs consist of hydrodynamically efficient tank barges coupled with high-horsepower tugs, allowing for improved maneuverability and sea-keeping.  Vessel cargo systems are designed to provide maximum flexibility and cargo integrity while also allowing for transfer rates of up to 20,000 to 30,000 barrels per hour, depending on vessel class. 

As of 2017, Crowley owns and operates 17 ATBs, which include 155,000-barrel, 178,000-barrel and 327,000-barrel capacity tank vessels at 96 percent, with each vessel having been chartered to leading companies in the petroleum and chemical industries.  Additionally, Crowley operates Jones Act tankers on behalf of other owners, which trade both domestically and internationally.

ATB Details

What is an ATB?

Articulated tug barges (ATBs) consist of a tank vessel (barge) and a large, powerful tug that is positioned in a notch in the stern of the barge, which enables the tug to propel and maneuver the barge.  Unlike an ITB (Integrated Tug/Barge), where the tug and barge are locked together in a rigid connection and become for practical purposes one unit, the ATB has an articulated or "hinged" connection system between the tug and barge.  This allows movement in one axis, or plane, in the critical area of fore and aft pitch.  No such movement is possible with an ITB unit.  Our ATBs make use of the Intercon Coupler System to mate the tug with the barge.

Advantages of ATBs

  • Improved reliability and safety over towed barges

  • Improved operating efficiency as compared to towed barges and tankers

  • Reduced customer operating costs due to an ATB's overall lower capital cost (when compared to new tankers)

  • ATBs can be delivered to customers in a fraction of the time that it takes to build and deliver new conventional tankers

How the Intercon Connection System Works

The Intercon System consists of a pair of port and starboard rams, which are installed in a structural support module on the tug. Each ram has a toothed “helmet” at the outboard end that engages a continuous rack of teeth on the barge notch wall, thus establishing a transverse, fixed horizontal axis about which the tug can pitch independently of the barge.

Onboard the barge, each side of the notch wall/skeg has a series of toothed castings vertically arrayed over a span representing the range of possible connection points between the tug and barge. The tooth pattern on the notch matches the tooth pattern on the tug, allowing for unlimited choices of draft on either vessel.

Intercon Connection

Intercon Advantages

  • Permits pushing in a wide range of sea conditions.

  • Increases speeds 35-40% over towed units.

  • Fuel savings enhanced by wheel and rudder efficiencies.

  • Fully eliminates hull contact between tug and barge.

  • Fail-safe mechanical connection with force monitoring.

  • Crowley Intercon Units are fitted with a hydraulic power back-up connected into the emergency generator circuit for added safety.

  • Engagement allowed regardless of draft or trim.

  • A mechanical drive with engagement safeguards is not vulnerable to hydraulic or pneumatic system failures.

  • Engagement and disengagement can take place without the crew on deck.

  • Eliminates expense and hazards of hawsers, headlines and cables.

  • A more comfortable ride reduces crew fatigue.

  • Unmatched maneuverability at sea and in port.

  • USCG approved for Dual Mode under NAVIC 2-81.

  • Worldwide product support from Intercon’s service facilities.

Designed and manufactured in America by one of the leading names in marine equipment.

ATB Vessel Specifications and Design Highlights

550 Class

650 Class

750 Class