Washburn & Doughty Associates, Inc. delivered the 5,000 hp Z-Drive Tug Independent to Marine Towing of Tampa. The 92 x 32 x 13.7-ft. tug is designed for ship handling and built to ABS Class Maltese Cross A1, Maltese Cross AMS, with notation: Towing Service and Fire Fighting Capability.
Independent admeasures 148 gt and has a Load Line based on USA flag registry and USCG rules. Bollard pull is estimated at 135,000 lbs ahead and 130,000 lbs astern.
Independent is powered by High Displacement Caterpillar 3516 B main engines - rated at 2,500 bhp @ 1,600 rpm - with electronic injection. The propulsion units are Rolls-Royce 1650H Z drives equipped with 2,400 mm stainless steel propellers and Kort nozzles with stainless steel liners
The vessel is equipped with two Caterpillar 3304 DIT marine package unit generators that provide 99KW @1,800 rpm, 208V 3 phase. One generator is normally on line while the other is on standby. In event that the on line generator fails, the switchboard and generator automatically start the standby generator, put it on line, and shut down the other generator.
Fernstrum grid coolers are used to cool the main engines and fire pump engine. The Z Drives are keel cooled by a welded channel cooler and the generators are cooled by circulating jacket water in the skeg void.
Independent is outfitted with Schuyler 16-in. laminated "soft loop" bow fender capped at the top of the bulwark with a 14-in. square hollow rubber fender. Schuyler also supplied the 12-in. black rubber "D" fender on the sides and stern. The "D" fenders are secured between two 1-in. plates about 4-in. deep with 1-in. pins on 11-in. centers.
The vessel is equipped with two 1,500 GPM SKUM Fire Monitors, with water and AFFF nozzles with local pick up, and an Aurora model 411 centrifugal fire pump. Power is provided by a Caterpillar 3406TA pump engine rated 440 hp @ 2,100 rpm. Deck machinery consists of a Markey model DEPC-48 electric hawser winch forward and an Almon Johnson 18-in. diameter series 351E electric capstan aft. The Siemens machinery alarm system consists of an integrated multi channel alarm system complete with sensors and local/remote alarm indicators. All components are completely modular and plug into a single dedicated backbone running fore and aft through the vessel.
Navigation and communications equipment include a Furuno GP-37 DGPS; a Simrad/Robertson AP9MK3 autopilot; a Simrad HS50 satellite compass; a Standard LH5 loud hailer; a Simrad RA53-4 radar; a Furuno 1953 C/NT radar; a Furuno depth sounder; and three Icom M127 VHF radios.