Carrousel tugs and another ASD for Multraship

Multraship are undergoing significant fleet expansion lately courtesy of Damen products including an ASD 2810 Hybrid tug. While this latest Carrousel tug order perhaps eclipses previous developments it was back in 2004 that Multraship refitted their 1961 built conventional tug Multratug 12 with a Carrousel arrangement. The addition of further references for the system is therefore particularly interesting.

There is a lengthy roll-call of participants in the project starting with Multraship who commissioned the tugs through their 100% owned subsidiary Novatug BV. They are based on Robert Allan Ltd.’s RAVE design (Robert Allan Voith Escort) and are to be built by Damen Shipyards Group. Construction is starting immediately under an agreement between Novatug and Damen subsidiary Van der Velden Barkemeyer GmbH, the hulls built by Hamburg shipyard Theodor Buschmann GmbH and final outfitting at Damen Maaskant Shipyard in Stellendam.

Safety enhancements and the ability to apply indirect towing forces are two key elements with the Carrousel towing system and the hardware itself is relatively simple consisting a freely rotating ring fitted around the tug’s superstructure, the towing point located on the ring rather than the traditional fixed towing point. The tug can turn around freely relative to the tow without releasing the line with the force (resultant on changing the towing point) affecting its centre relative to the tug’s centre of gravity.

The hull profile generates braking and/or steering forces based on lateral resistance of the hull through the water. Less energy, and consequently reduced fuel consumption and emissions with fuel savings of at least 25% are claimed depending on the operational profile but perhaps the most important statement in the system’s description is ‘A Carrousel tug simply cannot be capsized by a tow load’.

A significant factor is selection of the RAVE design with inline Voith thrusters powered by two ABC main engines of 2,650kW each providing a minimum bollard pull of 70 tonnes and free-running speed of 14 knots. The BV classed tugs will be 32m in length and are scheduled for delivery in first quarter 2017. Novatug will offer the Carrousel RAVE tugs on the basis of long-term bareboat charters, basically a financial or operational lease construction.

Leendert Muller, managing director of Multraship, says: “Safety is always our overriding objective, and that it is why we have opted wholeheartedly to produce the Novatug CRT. This new tug design, for the first time, eliminates what has always been the most significant threat to safety in towing – the risk of capsizing under a tow load. The benefits in terms of efficiency and flexibility, meanwhile, are also enormous”.

By Peter Barker