The design was produced by the Kooiman shipyard design office, working in close co-operation with consultants, the Technical Bureau Gommers, to ensure that the exact requirement of the owners were met. All four vessels were built in a very short time with all aspects of the construction, installation, pipework and the complete outfitting of the accommodation and wheelhouse undertaken in the Zwijndrecht shipyard.

Dutch Partner and her predecessors are 27.80m in length overall with a breadth (moulded) of 9.50m and a very shallow draft of less than 2.50m.

Other important aspect of the design are an adequate bollard pull of 30 tonnes and the large fuel and water tank capacities required for supply duties. The design and construction complies fully with the requirements of Lloyd's Register of Shipping, class + 100 A1 'TUG' LMC UMS and Dutch Shipping Inspectorate rules for undertaking international voyages of up to 200 miles from a safe haven.

The double chine hull is of all-welded steel construction, heavily strengthened by transverse framing. A raised forecastle affords good sea-keeping characteristics and a large clear after deck has 100m 2of free space. Course stability is enhanced by a skeg located between the two propeller nozzles and a rope guard is fitted to protect the nozzles and rudders. A steel rubbing-band is provided all round the vessel and the stem carries a heavy rubber bow fender. Internal tanks can accommodate 110m 3of fuel oil, 38m 3of fresh water, 12.5m 3ofsewage, 1.90m 3of dirty oil and a similar amount of lubricating oil.

All of the most recent tugs in this series are powered by two, twelve-cylinder, Caterpillar 3512 DITA main engines, each generating 1521bhp (1014kW), at a maximum continuous rating of 1600rpm. Power is transmitted to fixed-pitch van Voorden propellers via ZF reverse reduction gearboxes with a reduction ratio of 4.506:1.

The propellers rotate within fixed Hodi nozzles fitted with stainless steel liners to prevent undue erosion and damage from propeller tip cavitation.

A twin-rudder steering system incorporates a pair of unsupported, double plate spade rudders, operated by Flexion electrohydraulic steering gear. The latter has a pair of double-acting hydraulic cylinders giving maximum rudder angles of 70 degrees. This propulsion system gives the tugs a bollard pull of 30 tonnes and maximum free running speed of 12 knots.

Manoeuvrability is enhanced by an electrically powered Veth type VT-150 transverse bow-thruster rated at 160kW.

Electrical power is generated by three diesel/alternators sets.

The main generator is driven by a Caterpillar 3408 C diesel producing 280kW at 1500rpm coupled to a 350kVA, 380V, 50Hz alternator. The remaining generators incorporate John Deere 4045 TF 158 engines, each rated at 63kW at 1500rpm, driving 65kVA 230/400 V, 50Hz Stamford alternators.

Auxiliary systems installed in the engineroom include, a bilge pump, general service pump, sewage pump, fuel oil transfer pump, dirty oil pump, cooling water pumps, supplied mainly by Desmi. A fuel oil separator, bilge water separator and a fresh-water production plant were all from Houweling BV.

Towing gear includes a hydraulically driven Maaskant twin-drum towing winch with a maximum brake holding force of 50 tonnes and a line pull of 22 tons at 14m/min. The drums accommodate two towlines of 500m and 700m. The usual