A pair of new RAstar 3100 tugs for Signet Maritime of Houston, Texas

February 8, 2012


The Signet Constellation and Signet Stars & Stripes are the latest development in Robert Allan Ltd.’s RAstar series of tugs. These two powerful new escort tugs have been delivered to their owner’s – Signet Maritime Corporation of Houston, Texas. They were constructed to provide marine support services to Angola LNG Supply Services (ALSS) in the Port of Pascagoula, Mississippi. Designated as RAstar 3100s and designed by Naval Architects Robert Allan Ltd. of Vancouver, BC, they were constructed by Trinity Yachts LLC, at their Gulfport, MS shipyard. The names of these vessels pay tribute to past America’s Cup winners, the 12 meter yachts Constellation (winner in 1964) and Stars & Stripes (winner in 1987).


The particulars of this tug are as follows:


Length Overall
Beam, Moulded
Depth, Moulded
Load Draft, Maximum
Gross Tonnage
– 100′- 0″
– 92′- 1″
– 40′- 0″
– 17′- 5″
– 17′- 6″


Capacities are as follows:


Fuel Oil
Fresh Water
Lube Oil
Waste Oil
Oily Water
– 62,000 gallons
– 3,600 gallons
– 700 gallons
– 300 gallons
– 300 gallons


The Signet Constellation and Signet Stars & Stripes are classed for harbour, escort and emergency towing duties, with the following ABS notation; A1, AMS, Towing Vessel, Escort, Fi-Fi 1.

Propulsion comprises a pair of CAT C175-16 diesel engines, each rated 2,550 kW (3,418 BHP) at 1,800 rpm, each driving a Rolls-Royce model US 255 drive, with 2,800 mm diameter controllable pitch propellers through a composite shafting system.

The Signet Constellation and Signet Stars & Stripes are outfitted for a crew of eight (8) persons, in modern and well-equipped, air-conditioned accommodations.

The main hawser winch is a dual drum Markey Model DESDF-48, 200 HP, Electric, Escort Render / Recover Winch. The aft deck is equipped for emergency towing with 96 tonne SWL towpost.



Electrical power is provided by three (3) x Northern Lights M1066, generator sets rated at 99 kW @ 1800 rpm, all connected in parallel.

The tug has a full Fi-Fi 1 rating in accordance with Class notation requirements. The fire pumps are driven driven through gearbox with integral clutch and cooling system, which is driven off main engine front power take off via flexible coupling.


On trials, Signet Constellation met or exceeded all performance expectations, with the following results:


Bollard Pull, ahead
Free running speed, ahead
– 81 tonnes
– 13.5 knots


The RAstar series of Offshore/Escort Tugs by Robert Allan Ltd. have a unique sponsoned hull form, which has been proven in testing and real-world applications to provide significant enhanced escort towing and sea-keeping performance. Accelerations and motions are less than half those of comparable sized “standard” tug hulls. They are high-powered and manoeuvrable, typically intended for operations in weather and sea-exposed areas where a high standard of sea-keeping is required. The RAstar hull form is also energy-efficient, as the reduced waterline beam reduces free-running resistance considerably in comparison to other tugs of similar overall proportions. The unique hull form of the RAstar class, has been developed exclusively by Robert Allan Ltd. over many years of committed private research and development and is the proven standard in the escort tug world.



For more information on Signet Constellation and any other RAstar Series vessels, please contact us at design@ral.ca.