The OT&BE COSTWISE AT/B, now in its second generation of design, has been the subject of one of the most extensive model test programs ever completed for an AT/B. The model tests were performed in the 200m Clear Water Towing Tank at the Institute for Ocean Technology from July 2004 through January 2006. Additional model testing, in concert with Taisei Engineering, of Tokyo, was accomplished through 2008.

The goal of the testing was to create a large, high speed AT/B that accomplished three things.

• Higher speeds with reasonable horsepower.
• Fully comply with IMO Reg. 751 on tanker maneuvering characteristics.
• Allow the use of relatively simple hull forms to build.

The COSTWISE program was also focused on the need for adapting a tug and barge design to any service required, without extensive modifications needed to the basic design. The tugs for example, in the same hull, can accommodate a range of fuel types, from light distillate to IFO 380. The barge shape was designed to not only be friendly to oil and chemical transport, but with proportions and lines that also make it an ideal platform to meet the needs of cubic-intensive self-unloading bulk carriers and container barges.

There were also a host of secondary design issues we wanted to solve with this design. Things like low wake and wave making, utilizing “green” design in the tug and barge to reduce emissions and pollution, an effort to make the crew accommodation as comfortable as possible, and a major design effort to make the tug and barge easy to maintain and operate. This was accomplished by adding a workshop to the tug with enhanced material handling capability throughout the tug, and locating machinery for optimum maintainability.