Damen Shipyards Group has developed the reversed stern drive tug design that is particularly suited to terminal and confined harbour operations
Safety is a critical aspect in the tug business and the trend towards even more compact and powerful tugs, driven by larger vessels entering confined harbours and terminals, is challenging this. Combine this with a very competitive and opportunistic market and the tug industry finds itself in a highly challenging environment.
There are serious contradicting requirements to designing a tug that is fit for terminal and confined harbour operations. The tug design needs to combine compactness and high performance without jeopardising the safety of operations. “The amount of power available on a small vessel can be so high that the impact of inaccurate or wrong manoeuvres, for whatever reason, could be dramatic, if not dealt with in the right way, starting from the design,” said Damen Shipyards group product manager for tugs Dirk Degroote. He added: “Therefore, a well-designed tug nowadays requires in-depth knowledge of the dynamics in tug operations and calls for significant research and development efforts.”
This is why Damen combined all its research and knowledge when developing the reversed stern drive (RSD) tug, a compact tug design that is particularly suited to terminal operations and ship handling in confined harbours. The tug is a combination of a tractor tug (ATD) and an Azimuth Stern Drive (ASD) tug. The resulting RSD Tug 2513 design is a safe and compact, but very powerful and manoeuvrable tug.
“Our new RSD Tug 2513 has two bows, and therefore, it always sails bow-first. It is designed with a high freeboard and large beam to increase stability and safety,” said Mr Degroote. “And, to increase the safety of such a compact but high power design even further, the hull concept was combined with the patented Damen Twin Fin skeg design.”
He explained “This was first applied and proven on the successful ATD Tug 2412, and has now been further optimised through extensive computational fluid dynamics calculations in combination with some model test validations. This results in a very agile, but predictable sailing behaviour, enabling captains to deal with the highly demanding operations of today in a safe manner.”
Damen has added the familiar fast throttle response of the high speed propulsion engines to create a compact ship handling tug, with both higher performance and increased safety of operation. “To deal with the competitive market and to ensure short delivery times, a series of vessels is now under construction and the first delivery is planned within this year,” continued Mr Degroote.
Market trends are also driving Damen’s research and development in environmental systems and higher levels of automation. “There is increasing awareness of environmental aspects,” Mr Degroote added: “However, green tugs like hybrid or natural gas-driven tugs suffer from the severe competition in the market. This hardly allows for any additional investment in green technologies.
“It is our challenge to come up with solutions which enable environmentally friendly operations without losing competitiveness.” Therefore, Damen is further developing compressed natural gas technologies and hybrid technologies, building further on the experience gained from the seven hybrid tugs they built over the last three years.
It is also investing in more automation on its tugs. “Automation is definitely the future,” stated Mr Degroote. “The increasing importance of automation and sensor information on board is a logical next step, if you look at the levels of automation already available in cars or even the container terminals tugs are operating in.
“Therefore, we are also investing heavily in the electrical and automation field. This technology will help us to create even higher performing tugs, with reliable systems and increased safety of operation.”