Bis Viridis or "double green"

Bis Viridis during the show in Swinoujscie. The RSD series is attractive to towing companies as it allows only one type of tug to be used for all port operations. Currently, for their correct and safe driving, a typical ADF is used, assisted from the bow of the towed vessel and ASD from its stern. RSD works effectively both in front and behind the towed vessel.

On 24 August in Swinoujscie, the Damen group presented for the first time in Poland a new series tug, the RSD 2513. Its Latin name means “double green”, but it refers not only to the attractive color of the unit.

Regardless of the type of tug drive - conventional, rear-wheel drive ASD (Azimuthal Stern Drive) or ATD (Azimuthal Tractor Drive) and the design of the hull, they are all characterized by the highest efficiency, operational safety and forward traction. Reverse maneuvers, especially with a load, show their limitations. To remedy this, Damen began five years of research and development on a next-generation compact tug that does not have this shortcoming. It uses a number of innovations, including a patented, but not broken line of units of this class from the Dutch manufacturer, which ensured high reliability, efficiency and safety of use. The experience of operating vessels of the ASD 2411 and APD 2412 series was used. The tugs of the RSD 2513 project are medium-sized vessels optimized for operation in confined waters, i.e. in ports and wharfs, characterized by equal efficiency when towing forward and backward.

"Always a beak"

At first glance, it is clear that something is wrong with the Damen RSD 2513 tug. It looks like it has two beaks. Indeed, the height of the bulwark and freeboard at both ends of the vessel is the same. This reduces the risk of flooding the deck with rolls when it is loaded - at 18 °, the side of the ship is still 10% above the water level. The skipper is automatically notified of the dangerous degree of heeling. In addition, the ship has an unusual length-to-width ratio of almost 2:1 (length is 24,73 m and width is 13,13 m, which is the name of the model - 2513). But the most important innovation applied on the tugboat is the RSD system, or Reversed Stern Drive.

The RSD is a design that uses two propellers and two stabilizing keels (skegs) - narrow but high. They replaced one with another geometry (low and long) known from the most popular ASD and ATD models. As a result, and due to the hull design, the tug is just as efficient in both forward and reverse directions, unlike the ASD and ATD classes. In addition, traction and speed are almost the same. This is thanks to the Twin Fin system, i.e. two skegs, which, unlike one long skeg, do not adversely affect the thrust generated by the propellers in Kort nozzles, which are part of the rudder propellers commonly used in the port and on the roads. tugboats. It also reduces fuel consumption. As a result of this procedure, the RSD 2513 tug operates bow forward in all conditions, i.e. in the safest position, and may only have one towing winch. The Twin Fin also provides very good directional stability.

The bipedal Twin Fin patent has so far been applied to several "tractors" (ATD 2412) and two RSD 2513 tugs (Innovation and Bis Viridis) built to date. The next five RSDs are in various stages of production.

Innovative and proven

There are more innovative solutions on the RSD 2513 tow. These include a superstructure that is movably attached to the hull to reduce vibration and noise. This provides the crew with comfort for work and leisure. The chimney is integrated with its design on the sides, and the round glazing of the navigation bridge with large windows is made of impact-resistant material (Damen Safe Glass cat. P3A). protects the skipper in the event of, for example, the lobby being broken into. A light pile mast of a new design is mounted on top of the superstructure.

The operating system for managing ships and their mechanisms is based on the digital cloud, while its operation has simplified and intuitive interfaces, so that two panels on the bridge with a minimum number of buttons do not occupy the attention of the captain, who can only keep his hands on two joysticks. He controls the vessel, its movement and even communicates with the crew and pilot on the vessel under control. Two pedals are used to control the winch from the bridge. The high level of automation made it possible to reduce the number of crew even to two people (although its number depends on the equipment of the unit and the watch system). This significantly reduces operating costs, since the maintenance of the crew is about 40% of the costs in the life cycle of the tug. It is known that Damen is working on an automatic towing selection system that will limit the crew to only the skipper.

Another important innovation is Damen's SCR (Selective Catalytic Reduction) system to reduce NOx emissions in engine exhaust gases. Thanks to this, it is possible to reduce their content by 80%, which allows them to comply with the IMO Tier III standard. The SCR is offered as an option to shipowners operating in areas where these regulations apply. All Damen tugs are fitted with IMO Tier II compliant powertrains as standard.

In addition, a number of proven solutions are used in the tugs of the RSD 2513 project. Their working decks are free from obstructions - unnecessary equipment has been removed from them. The raised bulwarks (1,1 m) are smooth inside, without protruding stiffeners for the safety of the crew. It also facilitates maintenance and repair. These vessels are equipped with built-in closed-loop box coolers, which are also much less time-consuming to maintain. To reduce the amount of repair work, the units are covered with paint coatings with a service life of 5 years, the edges of the superstructure are rounded off, and some parts are made of stainless steel (for example, window frames or hawse elements on which the tow rope slides). Proven towing winches are manufactured with Damen, MTU and Caterpillar engines, as well as Rolls-Royce propellers. The side wing in the bow is designed to be safe from the forces generated when maneuvering large ships (the old tires are a thing of the past).

Innovation and Bis Viridis toured Europe visiting 34 ports including Swinoujscie and Gdansk.