Construction Continues on Three Z Drive Tugs at Washburn & Doughty Associates (USA)

Construction continues on three 86’ x 36’ Z Drive Tugs at Washburn & Doughty Associates, Inc. of East Boothbay, Maine. Commissioned by the Moran Towing Corporation of New Canaan, Connecticut, contracts were signed and construction began on these tugs in 2011. Designed by Jensen Maritime Consultants, Hulls 102, 103 and 104 will be used for ship assist and escort work. The vessels will be classed ABS Maltese Cross A1, Maltese Cross AMS, Towing Vessel, Escort Vessel and admeasure less than 200 gross tons US regulatory tonnage.

The tugs will be powered by two MTU 16 cylinder series 4000, M61 main engines each rated at 2680 BHP at 1800 rpm. The propulsion units will be Schottel model SRP 1215 FP drives, equipped with stainless steel propellers measuring 2400 mm and nozzles lined with stainless steel. Bollard pull is expected to exceed 60 mT ahead.

Lufkin model MV1600S reduction gears, with nominal gear ratios of 2:1, will be installed between each engine and Z drive to reduce the engine output speed to the drives. Straightline carbon fiber shafts are installed from the gears to the Z Drives.

The tugs will feature an AS-I machinery alarm system assembled by First Electric Motor Services and built from Siemens components.

These vessels will be outfitted with two John Deere model 6068TFM76, 1800 rpm marine engines providing 99KW, 120/208 VAC, 3-phase power. Under normal conditions one generator will be on-line for ship’s service and the other will be on standby. In the event that the on-line generator fails, the standby generator will automatically go on-line and the generator experiencing the failure will automatically shut down.

The main switchboard will be located in the engine room of each tug. They will be of the non-paralleling split bus type and fitted for automatic transfer from the on-line generator to the standby generator. The switchboard contains PLCs to control generator shutdown, transfer and starting. Override switches will be provided to operate the circuit breaker in event of loss of 24V power.

The tugs will be equipped with a Markey DEPC-48 electric hawser winch forward and a Markey CEW-60 electric hawser capstan aft. Two courses of cylindrical fender, with soft loop fender below, will cover the vessels’ bows. A course of D-fendering, measuring 12” x 14”, will be fitted at their main decks extending from the bow fenders at the sides and around the stern.

It is anticipated that the electronics package for each vessel will include two VHF radios, one loud hailer, two radars, one depth sounder, two DGPS, one AIS, one Sim-Motion System, one Blue Box System with five cameras, one Furuno RD-30 Weather Station and one satellite compass.

Moran gave special attention to crew habitability during the development of these tugs. Accommodations will be provided for six crew members with one stateroom on the main deck and three below.

Tank capacities are as follows:

Fuel Oil: 27,000 gallons

Fuel Oil Overflow: 1,000 gallons

Lube Oil: 1,000 gallons

Gear Oil: 500 gallons

Hydraulic Oil: 175 gallons

Gray Water/Treated Sewage: 2,000 gallons

Potable Water: 3,000 gallons

Ballast Water: 9,200 gallons

Dirty Oil: 500 gallons

[mappress]

Shipbuilding Tribune Staff, March 28, 2012; Image: washburndoughty