Tug Goes Green

Being green is fashionable these days. With ever stricter rules and regulations, the maritime industry is peparing to go green and sustainable projects can be found in every sector. A special project is the Green Tug Project, a cooperation between the three Dutch companies Offshore Ship Designers (OSD), Iskes Towage & Salvage and Damen Shipyards Hardinxveld.

The beginning of the Green Tug development goes back to 2008. Michiel Wijsmuller, president of OSD, explains: “We started the design for a low-emission harbour tug in 2008. In order to receive a partially Dutch government grant for the project, we partnered up with operators Iskes and Smit.” Other parties to give input were Bakker Sliedrecht, MARIN, Bureau Veritas, Nedstack Fuel Cell Technology, TNO and LindeGas. “Initially, we investigated a diesel-hybrid propulsion system with fuel cells powered by hydrogen. This proved to be quite expensive, though”, Wijsmuller continues. “During the project, we also designed a new, more efficient hull form, which was tested at MARIN. This hull form features a wider vessel for optimum stability and deck area. Making a conventional hull shape wider would increase the resistance of the vessel. By introducing box-shaped wings we still have a nice slender waterline.” Marc van der Zwaluw, OSD general manager, adds: ”Another advantage of this hull form is the improvement of the seagoing charateristics, as rolling motions will be reduced. Using CFD analysis enabled us to reduce drag in the range of seven to ten knots boat speed. In the tug’s real life this will result in a significant fuel saving.”

 

Multifunctional

Jim Iskes, owner of Iskes Towage & Salvage, decided he wanted to build this diesel- electric tug and contacted OSD. Wijsmuller: “We re-started this project halfway through 2011. The vessel is designed to be able to go to sea as well as sailing in the harbour.” Being multifunctional is important for Iskes: “We are a versatile company. Therefore we want to build tugs that we can use for offshore oil and gas and offshore wind jobs as well as harbour assistance and anchorhandling. The two green tugs we want, have FiFi1 – very important for operating in a tanker port -, winches and a heavy crane for anchor handling. It is a considerable investment, but in the end, it will be profitable. The vessel will be 32 metres long and have 70, maybe 80 ton bollard pull.”

Damen Shipyards Hardinxveld was asked to join the project. Managing director Jos van Woerkum: “We are specialised in custom-builds, have a lot of experience with captain-owners and are used to working with other engineering companies.” Currently, the three parties are in the final, detailed design stage. Van der Zwaluw: “The general arrangement and the specifications are finished, we now have to fine tune the plans and wait to decide what kind of equipment Iskes wants on board. Then we can draw the steel construction and make arrangements for the engine room and the wheel-house, all details that we have to think about carefully.” Iskes and Damen Shipyards Hardinxveld will together look at the suppliers and the equipment on board. Van Woerkum: “Halfway 2012 we want to start building the casco, the finishing phase will be late 2012 and mid 2013, the delivery is planned. Time flies, we now have to make sure to make decisions regarding the equipment and installations. Of course, we want high-quality equipment, but not too expensive. Also, maintenance and servicing costs should not be too high. We have requested several quotations and will choose the suppliers with which both of us feel comfortable.”

All equipment will be powered electrically. Iskes: “Hardly anything on board will be hydraulically powered. This means it is more sustainable, too, as there will be less oil on board. We want to have a s much green equipment on board as possible, like LED lighting, as we want to be considered for a CleanShip class notation by Bureau Veritas. We also plan to use green electricity for our batteries.” He laughs: “Maybe we’ll even get our own wind mill to supply our own energy!” The diesel-electric installation of the green tugs reduce the emission of NOx, SOx and CO2 by 30% compared to conventional tugs with the same tractive power operating in the harbours of Amsterdam and Rotterdam.

Van der Zwaluw explains: “The batteries on board have enough power to cruise half an hour with seven knots without using the diesel engines, so without the emission of any NOx, SOx and CO2. The vessels will reach their job mostly within half an hour, so when starting the job, the diesel engine is turned on, which recharges the batteries again.” Next to the environmental advantage, it will be a commercial advantage as well. Iskes Towage & Salvage’s managing director Ronald Vergouwen explains: “As fuel is getting more expensive, fuel costs become more and more important to our clients in the offshore market. They do not only ask for a quotation of the day rate, but also for a quotation of the fuel costs, as these are the biggest part of the total costs nowadays. Having an efficient diesel- electric installation is therefore a huge advantage.”

Unique partnership

OSD, Iskes and Damen Shipyards Hardinxveld all call their partnership and the project unique. Van der Zwaluw: “We have a very constructive partnership. Together, we bring our own specific knowledge to the table. Iskes has a lot of operational experience and gives a lot of input in the design based on that experience. Damen knows as no other how to competitively build a vessel and how to put it commercially into the market. And with all input, we try to make the best design possible.” Iskes adds: “Damen is a strong player in the tug market and knows how the tug market works, OSD is a specialist in designing these tugs. A perfect combination. Teaming up is ‘in’ nowadays. You see more and more companies working together. When working together, openness and honesty are very important. We do not keep any secrets from each other.” Van Woerkum agrees: “You must trust each other with the goal to create a solid, efficient and profitable vessel that will sell well. The partnership gives the project an extra dimension: we bring technology, design and experience together.”

Gail van den Hanenberg