Historic First in Towing Vessel Development from Robert Allan Ltd. and Multraship
A historic milestone in modern tug development was met this month when Multratug 32, the first new CARROUSEL RAVE TUG (CRT) was delivered to its owner, Novatug B.V. of the Netherlands. Multraship B.V. of the Netherlands will be the operator of the new CRT. Multraship and Novatug both belong to the Muller Maritime Group, that has been active in all types of towing operations for over 100 years.
This novel design features the RAVE tug concept, jointly developed by Robert Allan Ltd. and Voith Turbo GmbH & Co. KG, featuring VSP drives arranged inline on the hull centreline (image above), combined with Novatug’s patented Carrousel Towing System on the main deck (image below). The CRT Carrousel towing system was developed by Novatug in cooperation with Multraship as the group's harbour towage operator. Novatug also cooperated with Machinefabriek Luyt B.V. to develop and manufacture the special winch that is part of its Carrousel Towing System.
This unique combination of propulsion and towing arrangements provides inherently safer towing and escort operations, with enhanced manoeuvrability for operations in confined waterways. It is also much more flexible in its ability to provide thrust at towline angles not practical with conventional ASD or tractor tugs. The CRT is designed to safely produce escort steering and braking forces approximately 50% greater than any other type of tug of similar size, and can do this at greater speeds with significantly reduced risk. An additional benefit is the ability to produce the required forces with less installed engine power, thus improving fuel economy and exhaust emissions.
The concept of the RAVE tug design is the result of seven years of extensive collaboration and careful research between Robert Allan Ltd. and Voith. All predicted scenarios of the environmental conditions and operational manoeuvres of the RAVE tug were analyzed and checked during model tests, CFD analysis and in the Voith simulator with participation of experienced tug Masters.
The tug hull and other main steel components were fabricated and assembled by Theodor Buschmann GmbH in Hamburg. The assembly was then moved to Damen’s Maaskant Shipyards for final outfitting and completion.
Multraship and Novatug provided input from their unique experience gained from the development, construction, and safe and successful operation of the first ever Carrousel tug – Multratug 12. All this experience was summarized and implemented into the new advanced Carrousel System installed on the Multratug 32.
The CRT uses its lateral hull resistance and related hydrodynamic forces to create the maximum required steering and braking forces. The propulsion system is primarily used to control the tug’s heading, position and speed.
It is the tug’s relative heading that determines its effectiveness through the water and thus the magnitude of the towline force. At speed, significant hydrodynamic forces can be generated by simply applying minimal thrust sufficient to change the tug orientation to the escorted vessel. The capability and manoeuvring performance of this unique tug lead to significant fuel savings during operations and offers increased controllability, higher safe assistance speed in harbour or port and reduced time necessary for assistance.
The combined effort has resulted in the design, construction and delivery of the first CARROUSEL RAVE TUG, a vessel offering exceptional and very unique capabilities. This compact, 32 m tug, under 500 GT, can generate and safely apply forces during ship assist and escort operations up to 1.5 times more than any other type of similar sized tugs.
The tug demonstrates exceptional manoeuvrability; it can move in any direction with a reaction time of a few seconds and can generate maximum thrust through 360 degrees. It can work in confined spaces such as locks and narrow canals where other types of tugs simply cannot be effective due to water circulation effects.
The new CRT has all the necessary attributes of a standard tug such as sufficient and comfortable accommodation, large engine room convenient for service, and sufficient capacities of consumables. The wheelhouse has 360-degree visibility and a unique console arrangement for 360-degree operation. The tug is designed with all necessary safety measures that can protect tug and crew against damage from grounding, collision, flooding and fire.
The first trials showed that the tug is fully controllable, fast, powerful and has fully fulfilled the designer’s and Owners expectations. The CARROUSEL RAVE TUG can be considered a fully proven, state of the art ship-handling tug and definitely not just another experiment. Multratug 32 represents an extremely effective new tool for safer and more efficient ship assistance and escort.
For more information, please visit http://ral.ca/2018/02/21/historic-first-towing-vessel-development-robert-allan-ltd-multraship/.
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