The Corps of Engineers Marine Design Center in Philadelphia has contracted with the Jacksonville, Fla., naval architectural firm of Norman N. DeJong & Associates, Inc. for the design of a new series of twin-screw tugs. DeJong specializes in tugboat designs. The firm has designed tugs with a variety of propulsion systems, including rotating and cycloidal propellers.
The Superior-class tugs (named after Lake Superior) will be 105 feet by 34 feet. They will feature an operating draft ranging from 11 feet to 13 feet 6 inches, one-compartment subdivision, and meet damage stability criteria not normally associated with tugs.
The vessels will be ABS-classed for unlimited ocean service, ice strengthened, be loadlined, and constructed in accordance with USCG Subchapter I. Gross tonnage will be less than 200 tons. Design emphasis has been placed on noise abatement, maneuverability, fuel efficiency, low-speed handling characteristics, and crew safety and comfort.
An extensive model testing program, including flow and resistance tests with several different nozzle configurations, will be conducted. The model will be constructed by DeJong & Associates in its model shop in Jacksonville.
Major equipment will be selected within the next few months. It is anticipated that the tugs' twin engines with ducted propellers will develop approximately 80,000 pounds of bollard pull. Slip clutches will allow propeller control down to approximately 15 rpm for maneuvering around floating equipment, docks, and tending in tight quarters.