All four of the new vessels were ordered from the ASL Shipyard Pte Ltd in Singapore and are to the same basic design, classed by Lloyds Register +100A1 LMC Tug Coastal Service, UMS. Each vessel is 28.30m in length overall, with a beam of 11.70m, a maximum draft of 5.80m and incorporates a semi-raised forecastle. The first pair, named RT Stephanie and RT Claire, are powered by three Niigata 6L25 HX main engines generating a total of 5,220bhp (3,915kW) running at 750rpm.

Each main engine is coupled to a Niigata ZP 21 FP fully azimuthing propulsion unit via a Niigata Dual Modulation clutch. Two units are positioned forward and one aft – in the usual ‘Rotor Tug’ configuration. On trials this arrangement gave the tugs a aximum bollard pull in excess of 68 tons, with a free running speed of 12 knots.

Hydraulically powered single drum towing winches are installed aft and on the foredeck. The winches are identical andhave a maximum brake load of 150 tons and a line pull of 30 tons on the first layer. Each drum carries a 200m steel wire towline of 48mm diameter, with a 10m pennant of synthetic fibre rope of 100mm diameter.

A basic fire fighting system comprising two monitors mounted on the wheelhouse, a self protection spray system, and Fishcon fire pumps of 1,200m3/hr is fitted to the first two tugs but the system is uprated to full FiFi 1 standard on the second pair. The wheelhouse is equipped with a Niigata ‘Unilever’ single ‘joy-stick’ control system, encompassing all three propulsion units, an advanced engine monitoring system, and integrated bridge watch equipment. A Furuno navigational equipment package includes, radar, DGPS, auto-pilot, echo-sounder and rate of turn indicator.

Communications equipment is installed to GMDSS standards for harbour and coastal operation. Fully air-conditioned accommodation is provided for a normal compliment of up to six persons in two single and two twin berth cabins.

The first vessel, RT Stephanie, arrived in Rotterdam late in October and RT Claire is currently on route to Europe with a crew from ship delivery specialists Redwise Maritime Services BV. It is likely that both tugs will operate for a short time in the Rotterdam area as part of the rew training process. In the meantime, the second air of ‘Rotor Tugs’ are nearing completion at the ASL yard in Singapore. Both vessels, RT Anthonie and RT Zoe, have been launched and are currently being fitted out. Although built to the same basic specification, his later pair will be fitted with a propulsion package from Wärtsilä.

Three Wärtsilä 8L20 main engines running at 1,000 rpm will produce a total of 5,600bhp (4,120kW) to drive Wärtsilä/Lips CS200 CP azimuth thrusters fitted with controllable pitch propellers rotating in HR nozzles. This arrangement is expected to give the vessels a bollard pull of over 65 tons and a free running speed of 12 knots. Kooren Shipbuilding and Trading are currently in the process of tendering for an additional four RT-80 Rotor Tugs, with the possibility of options for a further four. These tugs will be similar to the present RT-60 design but with further small changes and a bollard pull  in excess of 80 tons.

By JACK GASTON