Seaway Trident Design and Construction Support

  • Client:
    Great Lakes St. Lawrence Seaway Development Corporation (GLSLSDC)
  • Completion Date:
    June 2023
  • Key Collaborator:
    Markey Machine
  • Project Type:
    Vessel Design & Modification, Tugs & Workboats
  • Service Categories:
    Naval Architecture
    Marine Engineering
    Owner Services & Onsite Support
  • Vessel Overview:
    60-foot (18.3-Meter) Ice-Capable Harbor Tug
  • Challenge:
    Develop a design for an ice-capable harbor tug with year-round operations.


The Seaway Trident is a highly customized, ice-strengthened tugboat based on Glosten’s HT-60 concept. We adapted the design for the Great Lakes St. Lawrence Seaway Development Corporation, who were in the market for an agile tug that could weather the icy conditions of the St. Lawrence Seaway while performing construction work, routine maintenance of aids to navigation, and ice management in and around lock chambers. Glosten customized all elements of the design to enhance the Trident’s ability to perform its intended work functions.



At 60 feet (18.3 meters) in length, the tug is right-sized for maneuvering inside lock chambers, with a wide 28-foot beam to improve performance in ice and enhance stability for deck crane operations. Schottel Z-drive units are powered by a pair of Caterpillar C18 diesel engines turning carbon fiber shafts for a combined 1,300 bhp at 1,800 RPM. To effectively perform its duties in ice, the hull was strengthened to ABS Ice Class C0 standards. The deck is outfitted with a Markey Machinery headline winch and a fully foldable Heila Marine deck crane.

After completing a contract-level design package and technical specification, Glosten’s role on the project continued with onsite support at Washburn & Doughty during the Trident’s construction, launch, and sea trials.

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