Understanding an Underperforming Vessel.

The dredge tender W.E. Ivanoff was built to maneuver the Port of Portland’s dredge Oregon and its pipelines as it performs maintenance dredging along the navigation channels of the Columbia and Willamette Rivers. The Ivanoff lacked the required propulsion and steerage, both ahead and astern, to meet the Port’s operational needs. Despite having more power, the Ivanoff was routinely outperformed by the Port’s other dredge tender, the Clackamas.

In 2015, the Port of Portland commissioned Glosten to investigate design improvements to the Ivanoff. Glosten determined that the Ivanoff’s performance issues were related to the stern hull shape, rudder configuration, and propeller size. After discussions with the Port, it was decided that the best solution would be to completely redesign the vessel’s stern and propulsion system.

Computational Fluid Dynamics (CFD) analyses provided baseline comparisons of the original Ivanoff hull and the hull of the Clackamas. These analyses provided quantifiable metrics that showed the Clackamas hull was superior to the original Ivanoff hull, matching the real-world results from a head-to-head push test. Glosten then designed and modeled a new Ivanoff stern using CFD to add to the comparison. This final analysis showed a significant improvement over the original design as well as over both the Port’s other dredge tenders, Clackamas and W.L. Williams. The new stern shape also allowed additional improvement gains through increased propeller diameter and pitch, an associated decrease in gear reduction ratio, and much larger rudders, facilitating the Port of Portland’s desired performance improvements.