Both vessels were built to a new design for a practical and economical anchor-handler designated the Stan Tug 4011.

With the exception of the main engine installation the tugs are equipped and fitted out in exactly the same manner. For operational reasons sister ship Jabbar, delivered two months earlier, was given a more powerful propulsion system.

Wassay and its sister are equipped and fitted out to a very high standard for towing, anchor-handling, fire fighting, diving support, pollution control and stand-by-safety and rescue operations. The tugs are classed by Lloyds Register +100A1 Tug Unrestricted Service +LMC and comply with SOLAS including Section V, Load line, Marpol, Colreg, IMO and GMDSS Area 3.

The hull and all major steelwork was constructed by a shipyard in Poland under the supervision of Damen inspectors and towed to the Netherlands to be fitted out under cover in the assembly hall at Gorinchem.

A heavily built structure of 40.75m in length overall the hull has a beam of 11.22m and draft (aft) of 4.75m. The double chine hull affords good water-flow to the twin screws and nozzles and incorporates a large skeg aft. Integral tank spaces enable 315.6m 3of fuel to be accommodated and 49.4m 3of fresh water. A full-height forecastle is reinforced with external steel rubbing strakes and carries a substantial rubber bow fender. The open stern is fitted with a stern roller and a strengthened deck accommodates hydraulically operated towing pins and fork type wire/chain stopper. A large clear working deck has a protective wood sheathing and has recessed strong points for securing cargo.

Wassay is powered by two Caterpillar 3516B TA diesels running at 1600 rev/min to produce a total of 4000bhp (2982bkW). Power is transmitted to a pair of Promarine fixed pitch bronze propellers via Reintjes WAF 872 reverse/reduction gearboxes. The propellers rotate within fixed Van de Giessen nozzles of 2500mm diameter. On trials in Europort, witnessed by Maritime Journal, this propulsion system delivered a static bollard pull of 58.5 tonnes with very little evidence of propeller noise or vibration. This figure exceeded that required by the specification by a healthy margin. During speed trials Wassay achieved a maximum free running speed of 12.7 knots.

Sister ship Jabbar was fitted with more powerful Caterpillar 3606 TA diesels delivering a total of 5444bhp (4060bkW) at 1000 rev/min to larger propellers and nozzles. The result was an increase in bollard pull to 73.3 tonnes and a slight increase in speed to 13.2 knots.

Wassay and its sister ship are unusual in that virtually all of the auxiliary systems are self powered, without reliance on power from the main engines.

An electrically driven transverse bow thruster of 536bhp is fitted to aid manoeuvrability and accurate positioning. Electrical power for the thruster is supplied by a dedicated, Caterpillar 3412C TA, generator set. The vessel's main electrical system is supplied by two Cat SR 4 alternators, powered by Caterpillar 3306B TA diesels, each rated at 181kVA at 50Hz 240/415v AC. An air-conditioned control room, with direct access to the main deck via stairs, houses the main electrical switchboards. In compliance with SOLAS requirements an emergency generator is located separate from the engineroom at main deck level. The 60kVA Caterpillar 3304B NA diesel generator is radiator cooled.

A further Caterpillar 3306B TA drives the pump for the main fire fighting system, giving an output of 426m 3of water per hour.

On deck, the main towing and anchor-handling winch is a self-contained twin drum 'waterfall' unit powered by another dedicated Caterpillar 3406 C/TA diesel via a torque converter. The winch was manufactured by Ridderinkhof and has a stall load of 165 tonnes and a line pull of 85 tonnes at 10m per minute. Two Ridderinkhof tugger winches are located on either side of the main winch and have a maximum pull of 10 tonnes at 18m per minute.

A Mampaey quick release towing hook, with a safe working load of 101.9 tonnes, is fitted for auxiliary use. As already mentioned, towing pins and line handling gear are fitted, capable of dealing with towing or anchorhandling gear of chain or steel wire rope. The necessary brackets have been put in place to . .

. . accept a portable 100 tonne 'A' frame should it be required.

Located at boat deck level is a hydraulically powered Heila HLRM 45-35+3PM deck crane with a capacity of 15.4 tonnes at 2.91m reach.

Two, high holding power, 'Pool' anchors of 585kg each, are handled by a Kraaijeveld anchor windlass mounted on the foredeck. The windlass has a hauling speed of 10m/minute and is fitted with two warping heads.

A SOLAS compliant fast rescue boat is located on a cradle and served by a separate davit on the boat deck. The fire fighting system includes two remotely operated water/foam fire monitors mounted on a platform above the after end of the wheelhouse roof and a self-protection spray system. Oil dispersant operations can be carried out using a pair of spray booms and their associated pumping equipment. Dedicated tanks are provided with capacity for 29.2m 3of fire fighting foam and 12.8m 3of chemical dispersant.

In order to support diving operations, a decompression chamber is installed in a dedicated cabin located on the port side, adjacent to the winch and easily accessible from the after deck.

The 1.6m diameter chamber is served by two high-pressure, and one low-pressure, air compressors.

Wassay has a very large wheelhouse with control positions fore and aft. Main propulsion and bow thruster controls are available at each position, along with essential navigational equipment and VHF radios.

Controls for the winch are located at the after control station and duplicated in a cabinet outside on the boat deck, both with a full view of the working deck aft.

Navigational equipment includes a Plath Navigat X gyrocompass with input to a Navipilot ADII autopilot. Two Decca Bridgemaster ATA 251/6 radars are installed, a Koden KGP 913 DGPS, a Skipper EF 603 echosounder and Furuno DS-80 speed log. The communications outfit includes VHF, SSB and Inmarsat equipment in a Sailor 4000 system. A Sailor UAIS- 1800 automatic vessel identification system is also fitted.

Fully air-conditioned accommodation is designed for up to 18 crew and 8 charterers personnel in well-fitted cabins.

A very large mess-room, galley, sanitary and washing facilities, an emergency treatment room, charterers office and stores are also provided.

Wassay and Jabbar will join the existing fleet of Gulf Services Office at work in the Arabian Gulf. The tugs will be engaged in supporting the laying and maintenance of offshore pipelines.

Much of the work is involved with laying and retrieving anchors for specialist pipe-laying barges.

This involves handling anchors of up to 80 tonnes and carrying out associated towing operations.

Where necessary the tugs are used as stable work platforms for diving and other on site services.

Damen Shipyards have had a long association with the owners, who operate a number of tugs built by the Dutch shipbuilders in previous years.