Reducing Downtime for the Kingston Passenger Ferry Dock

Abstract: This study addresses the operational challenges faced by Kitsap Transit (KT) in maintaining uninterrupted passenger ferry services at the Kingston Dock, located in Kingston, WA. Serving multiple functions including passenger-only ferry operations, overnight and heavy weather moorage, and maintenance, the dock is susceptible to environmental elements that endanger KT's assets, passenger safety, and service continuity.

Originally designed for a smaller ferry vessel by a private operator, the dock's orientation, which was determined by factors such as environmental impact and construction costs, does not align with KT's current operational needs. With larger vessels now in operation, issues such as motion induced by wind, waves, and vessel wakes have become persistent concerns. Although fendering modifications were made to mitigate damage, they fail to address the challenges posed by larger vessels and increased float motion.

An additional challenge for any improvements is the presence of seagrass and eelgrass along the edge of the dock. The water depth at the Kingston Dock is approximately 12 feet mean lower-low water (MLLW). When looking at the water depths near the public fishing pier and known eelgrass beds, it appears the Kingston Dock was located and oriented as close to shore as possible while maintaining sufficient operational depth below the keels, maneuverability of the vessels adjacent to the WSF terminal, and minimizing environmental impact to the eelgrass beds.

Several alternatives have been considered/identified for further evaluation:
• Protection from waves and vessel wakes by adding generic breakwaters or wave screens or moving the dock to within the jetty breakwater;
• Changing the orientation of the dock;
• Changes to the hydrodynamic properties of the dock through motion damping systems, and use of materials with a different natural period (i.e., concrete pontoons); or
• Some combination of the above.

This study explores alternative solutions aimed at enhancing passenger safety, providing heavy weather moorage, and minimizing environmental impact and costs. Through evaluation and screening, it was determined that reorienting the dock in alignment with the primary wave direction is the most effective approach to reducing motion. Passive measures like fixed or floating breakwaters were found insufficient due to proximity to the Washington State Ferries (WSF) terminal and inability to mitigate various wave periods.

Recommendations include reusing the existing dock in a reoriented position to improve passenger embarking/disembarking safety and installing mooring dolphins to enhance vessel moorage during heavy weather conditions. To validate these recommendations and guide engineering design, site-specific data collection for wind and waves, structural inspections, and modeling of dock-vessel interactions are recommended.

This study provides insights into optimizing passenger ferry operations, enhancing safety, and ensuring service reliability in challenging marine environments, benefiting both KT and its passengers.

How does this project / topic contribute to the advancement of the industry and profession?: Lessons learned from this project, including the alternatives considered, will help other ports and harbors that deal with similar challenges. With more frequent and more intense storms occurring as a result of climate change, operational conditions are changing, and ports have to find economical approaches to accommodating these anomalous weather events and their impacts on operations of passenger ferries.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: New and state of the art numerical modeling techniques have been used to examine environmental stressors.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: Finding an economical solution to minimize downtime for the port was challenging given regulatory and environmental constraints. We developed several alternatives to help the client arrive at a decision.

Who is the target audience for this paper?: Ports and harbors that operate passenger ferries and cruise lines.