First AZ 30/80 Class tug Signet America launched

October 30, 2007


On October 29, 2007, the first of Class Signet America, a new AZ-30/80 Class tug, was launched at J. M. Martinac Shipbuilders in Tacoma, Washington. This unique new tug is scheduled to be delivered to its Owners, Signet Maritime Corporation of Houston, Texas early in 2008. Signet America is the first of this new class of powerful ship-handling/escort tug, and was developed by Robert Allan Ltd., Naval Architects of Vancouver, B.C., to suit the unique operational requirements of this owner, and the physical restrictions (primarily a limiting draft of 17 ft, 6 inches) for operations in the La Quinta channel in the port of Corpus Christi in which it will operate. The role of this tug will involve not only conventional ship-handling and escort work, but a lot of rig-handling and some short-haul coastal towing. After much deliberation and examination of other existing well-proven Robert Allan Ltd. designs for these roles, the Owners determined that a purpose-built, new design was required. The AZ 30/80 is the result.

The tug was built to ABS Class notation ” ✠ A1 Towing Vessel, ✠ AMS, Escort, Fi-Fi 1″.


Particulars of the Signet America are as follows:


Length Overall
Beam, Moulded
Depth, Moulded
Draft, Maximum
Fuel Capacity
Potable water capacity
– 98 ft – 0 inches (29.9 metres)
– 40 ft – 0 inches (12.2 metres)
– 17 ft – 5 inches (5.3 metres)
– 17 ft – 6 inches 5.3 metres)
– 46,176 U.S. Gallons (174.8 cu. metres)
– 3,596 U.S. Gallons (13.6 cu. metres)



Propulsion comprises a pair of MTU 16V-4000 diesel engines, each rated 3305 BHP (2,465 kW) at 2,000 rpm, and each driving a Niigata model ZP-41 Z-drive with a 2,700 mm diameter propeller through a hollow, in-line shafting system. This combination is predicted to deliver a Bollard Pull of 80 tonnes ahead, 75+ tonnes astern, and provide a free running speed in excess of 12 knots. Signet America is outfitted for a crew of up to six persons, in modern and well-equipped facilities. The Master and Chief Engineer have large cabins on the main deck with a shared en-suite lavatory. The crew are accommodated in two double cabins in the lower deck space forward. A spacious, open-plan lounge and mess area dominates the main deck, served by a fully-equipped galley. An open breezeway and access corridor across the deckhouse enables all the interior accesses to be placed in a very sheltered location close to the centreline of the tug, minimizing the potential for any ingress of water below decks, as well as providing a full acoustic break between the noise source of the exhaust casings and the crew quarters and wheelhouse. A deck-accessible toilet is also accessed off the breezeway for crew comfort.

The main hawser winch is a single drum, Model DEPCF-52S electric winch supplied by Markey Machinery of Seattle, WA. The winch has a line capacity of 750 ft (228.6 metres) of 10″ circumference (80 mm dia.) synthetic line, a brake capacity of 307 tonnes (1st layer), and a line pull of 30,818 lbs (13,976 Kg) at a speed of 73 fpm (22.2 metres/minute) or 7,705 lbs (3,494 Kg) at 145 fpm (44.2 metres/minute) – 1st layer.

Electrical power is provided by a pair of Northern Lights gen-sets, each rated 99 kW.



The tug has a full Fi-Fi 1 rating in accordance with Class notation requirements. The two Stang/Counterfire 6,200 gpm fire pumps are each driven VIA a PTO off the front of the main engines.

Fendering of the Signet America was provided by Schuyler Rubber, and comprises a Shibata 800 mm OD cylindrical bow fender, above an array of Schuyler “soft-loop” fenders which extend around the full length of the main deck.

The layout of Signet America is shown on the accompanying General Arrangement drawing. Under the direction of Project Manager, James McCarthy of Robert Allan Ltd., the Owner’s objectives have been fully satisfied with this handsome and powerful new tug, well executed by the builders.

The vessel is scheduled for delivery at the end of 2007.

For further information on this or any other high-performance vessel designs, please contact us.