First Damen Reverse Stern Drive Tug to launch in 2017
Damen will launch the first tug of its new Reverse Stern Drive (RSD) series – the RSD Tug 2513 – in April 2017. The RSD Tug 2513 has largely evolved because vessels are getting bigger and harbours have to be more efficient. This compact, robust vessel is particularly well designed for handling at the flare of vessels.
Coen Boudesteijn, Damen Product Director Tugs, says the new type builds and improves upon the highly successful Damen ATD Tug 2412. “This is the next step. Major operators such as KOTUG and Svitzer are very enthusiastic about the ATD Tug 2412’s performance, manoeuvrability and handling speed. And harbour authorities appreciate its high performance. She is a very safe ship handling tug operating in ports from Hamburg to Sydney.”
Worldwide patent for unique twin fin hull
The RSD Tug 2513 is the only compact tug designed to work bow first. “Operators never have to reposition their tug because they work well indirect or direct – at all speeds, sailing ahead and astern,” he adds. In February, Damen was granted a worldwide patent for the unique twin fin hull for the new vessel type. “Like all Damen vessels, she will be compact, efficient and very powerful but with an added performance boost from the new twin fin hull.”
The successful twin fin design represents years of Research & Development. Damen has been testing many variations of skeg designs at Maritime Research Institute Netherlands and in real life with the ATD Tug 2412. This continual process looking to improve has paid off, Coen stresses. At 13 knots there is always full control ahead or astern, he explains. “The vessel can sail at a 30 degrees correction and come back, all with 100% control. And even at 13 knots she has a dry deck.”
The RSD Tug 2513 is very easy to turn, he emphasises. “During escorting at 6-10 knots, the vessel is dynamically much better than a single skeg. The twin fin makes her very stable, going from 0 degrees to 70 degrees smoothly. When steering, the operator always has a high line force.”
With a 3516B Caterpillar engine, the RSD Tug 2513 will have efficient fuel consumption. She is powerful and will realise a minimum of 70 tonnes bollard pull in both directions and this is more likely to be 75 tonnes astern.
In the near future the RSD series will comprise the RSD 2210, (50 tonnes bollard pull), the RSD Tug 2914 (90 tonnes bollard pull) and the CNG version.
Damen Compressed Natural Gas RSD
This new RSD diesel tug will also be further developed into the world’s first 100% Compressed Natural Gas (CNG) RSD tug, the prototype of which will be tested in 2017 ready to enter the market in 2018.
For the CNG version, Damen is working with German engine manufacturer MTU Friedrichshafen, a subsidiary of Rolls-Royce Power Systems and leading Danish operator Svitzer. Bureau Veritas is also a partner in the development. The Damen RSD CNG Tug is essentially the same as the new RSD Tug 2513: designed as a compact, 25m harbour tug but instead running on gas.
Working under flare
Damen has taken quite a different approach to what is already available on the market as gas-powered tugs tend to be much larger. Coen elaborates: “Compact tugs are in our bones. The RSD CNG Tug will be much smaller than anything out there, which are typically 34 to 36m. We believe that a compact tug is more attractive cost wise but also she can work under the flare of the vessel unlike others.” While the vessel is compact, she is still powerful achieving 70 tonnes bollard pull. This special vessel is being developed under the European Union’s Lean Ship Programme.
The MTU 16-cylinder engine enables the vessel to sail for one week without refuelling. This is an excellent engine for ship handling, with very quick acceleration, stresses Coen. The gas engine for the new tugboat is based on the proven MTU Series 4000 M63 diesel engine. This will be complemented with a multipoint gas injection system, a dynamic engine control and an optimised safety concept.
“We are developing our new gas series in order to meet the extreme load profile of the tugboat. The acceleration will be comparable to the level of our diesel engines. Due to the clean combustion concept, compliance with IMO Tier 3 emission legislation will be ensured without the need of additional exhaust gas after treatment. The 2,000 Kw MTU gas engine is characterised by high power density combined with low fuel consumption,” says Dr. Ulrich Dohle, CEO of Rolls-Royce Power Systems AG.
This vessel will be ideal for the many LNG terminals worldwide, he adds. And with this in mind Damen is also working on designs for a bunker barge and refuelling station for the CNG vessels.