When inland shipping entrepreneur Wilco Ooms started planning his new vessel in 2004, his vision was to create a ship with less fuel consumption, less emissions, a greater carrying capacity and a smaller draught than what is currently the norm in the 110 metre length by 11.40 metre beam imposed by the European waterways.

To achieve this goal, Ooms realised that he needed to start with a clean drawing table, where hull design, propulsion arrangement and the shape of the hold could be matched together to obtain the optimal compromise. As a basis for the optimisation, the usage profile of Ooms' current ship, called Carpe Diem, was analysed. One fact became clear instantly: at 40 % average loading, the propulsion installation was not as efficient as could be.

Hull shapeThe hull design of inland barges is often considered as a given, as it has evolved for decades into the most used form today, with full bow sections and deep propeller tunnels in the aft. These propeller tunnels and their walls on port and starboard ensure proper immersion of the large propellers when the barge is sailing in

light-loaded condition, which is about 10% of the time in Carpe Diem Shipping's calculations. During the remaining 90% of the time however, the propeller tunnels are a source of extra resistance. Especially when heavily loaded in shallow water, and water for the propellers has to come from the sides, not from below, the deep propeller tunnels prove to be a less-than-ideal hull shape.

The hull of Semper Fi was designed in collaboration with the Dutch maritime research institute MARIN. An analysis with Computational Fluid Dynamics (CFD) software showed various points of higher pressure on the hull, which were eliminated by increasing the bilge radius in the foreship and tightening the bilge radius in the aft, where the parallel midship transitions into a pram-type stern with

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OwnerCarpe Diem Shipping, the Netherlands

Principal particularsLength o.a. 110 mBreadth mld. 11.41 mDepth 3.70 mDraught 3.69 mCargo hold capacity 3,600 m3

Displacement 4,200 m3

Main engines 2 x 515 kWMain auxiliary generators 2 x 634 kVAElectrical propulsion motors 2 x 330 kWHarbour generator 1 x 40 kW

Z-drive thrusters 2 x 845 kWBow thruster 1 x 440 kW

Fuel tanks 58 m3

Luboil tanks 3.6 m3

Fresh water tanks 25 m3

Gray water tanks 6.5 m3

fairly flat V-shaped sections. Upon completion of the hull design, a model was tested in the towing tank for verification.

Propeller efficiencyInstead of looking for propeller efficiency in a large propeller diameter, Ooms opted for azimuthing Veth-Z-drives with counter-rotating propellers, as applied in river cruise vessels for many years. Where normal propellers in this range have a diameter of about 170 to 175 centimetres, the propellers on Semper Fi have a diameter of 150 centimetres forward and 135 centimetres aft. Because the aft propellers rotate in the opposite direction as the forward-facing propellers, a lot of the rotational energy – normally considered a loss – is converted into forward thrust. Martin van der Jagt from Veth Propulsion: "When all losses and

benefits are taken into account, the Z-drives have an efficiency that is about 3% higher than a standard in-line propeller shaft installation. We see an evolution towards rudderpropellers throughout the inland shipping sector, with half of the hulls for inland barges currently on order designed for the use of either Z-drives or L-drives. For river cruise vessels, that ratio has been at 90% for many years, because of the silent operation, space saving design and improved manoeuvrability."

Another benefit of the CFD calculations was that streamlines could be computed, not only on the hull surface – as they can be made visible with paint stripes during towing tests – but also at various distances from the hull. Based on these results, it was decided to mount the azimuthing thrusters, not flush with the bottom plating, but at a five degree angle towards the plating. This ensures that the propellers are positioned perfectly perpendicular to the flow, which enhances their efficiency. During operation,

SEMPER FIINNOVATIVE PROPULSION CONCEPT AND HULL DESIGN

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''The hybrid propulsion system with Z-drives, alongwith an optimised hull shape, will reduce

fuel consumption in several loading conditions''

The hold is suitable for containers as well as bulk transport

© Reprinted from Maritime by Holland Magazine, No. 8, December 2012, www.maritimeholland.com. Publisher: Navingo BV, www.navingo.com

Ooms will experiment by varying the angles between the thrusters and the centreline. It is expected that particularly in shallow waters, where more water comes from the sides and less from the keel, it may be advantageous to angle out both thrusters, even when sailing straight ahead. In a later phase, such an angle could be set automatically, based on the depth readings.

BowthrusterA lot of thought was also put into the selection of the bowthruster. The Veth Compact Jet thruster came out as the winner of the vetting process. Albeit more expensive than the typical tunnel thruster, this thruster, often found on river cruise vessels for its quiet operation, presents some significant advantages:– Less entrapped water means a weight saving

of about ten tons;– The thruster is also effective when the vessel

has forward speed;– Due to the slender foreship of Semper Fi,

tunnels in the side would have generated significant added resistance;

– Very suitable for use in a dynamic positioning system.

To keep the number of strategic subcontractors to a minimum, Carpe Diem Shipping sourced almost everything related to propulsion from Veth Propulsion, including the Scania main engines and generators, two 330 kW electric motors, two Veth hybrid Z-drives, the bowthruster, three water-cooled variable frequency drives, the exhaust treatment systems and the complete propulsion and power control system.

Hybrid DD - DEFor generating the propulsion power, all options were considered, ranging from dual fuel (LNG + diesel) engines to hydrogen fuel cells. The final choice was made for a hybrid propulsion arrangement: basically a direct drive system with diesel-electric assistance. After Geo Focus and Duandra, Semper Fi is the third ship this year to be featured in Maritime by Holland Magazine with such a propulsion layout. The advantages are clear: the smaller main engines are properly loaded in the most common sailing scenarios, and there is no conversion loss in this operating range as in a pure diesel-electric installation. When heavy loading, wind or current call for more propulsion power, one or two gensets can add power through an electric motor on a power-take-in shaft. In light-loaded conditions, both main engines can be turned off and the entire vessel can be run from a single generator, roughly half the size of a conventional main engine.

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''Semper Fi's emissions are

further reduced with an

exhaust post-treatment system''

The hybrid thrusters are slightly angled to align better with the flow

On Semper Fi, the electric motor is not connected to a free-standing gearbox, but it is connected to the azimuthing Veth-Z-drive thruster at a 90-degree angle. Actually the main engines are mounted transversally towards the outboard sides and the e-motors are mounted in the fore-aft axis, resulting in a very short engine room. This is the first ship to feature the new Veth Hybrid Z-Drive, which was introduced in 2011. During sailing on the main engines, the asynchronous electric motors can also be used as generators, to supply power for reefer containers or the general board net. On Semper Fi, they can even charge a battery bank of 4,400 Ah, which - through inverters – can take care of the house load by supplying 15 kW for at least six hours. Still, a small 40 kW genset is provided for harbour service. Another reduction of the fuel consumption was achieved by recuperating waste heat from the generators to heat the accommodation through a floor-heating system.

EmissionsBecause the main engines - and their identical counterparts in the gensets - are marinised truck engines, off-the-shelf exhaust post-treatment installations could be sourced from the automotive industry. On Semper Fi, the exhaust gases of each large diesel engine pass first through a CRT (continuously regenerating technology) diesel particulate filter. As the propulsion arrangement has eliminated long periods of stationary running, the exhaust gases are sufficiently hot at all times, which means a heat source for regeneration of the particulate filters is not necessary. After the CRTs, ureum (commercially available as Adblue) is injected, which reduces the NOx levels by 84%. Finally, before exiting the engine room, the exhaust gases pass through noise dampers eliminating the exhaust noise. With its propulsion system and exhaust gas treatment system, Semper Fi scores below the future emission standards by a large margin.

HoldBecause of the longer foreship, two container positions in the lower level of the hold were lost, but this is compensated by adding 1.5 metre length at the aft end of the hold. The extra length allows to stack 45-foot containers at the aft instead of 40-footers without losing other container positions. The space on the aft mooring deck has been reduced to the absolute minimum. The hold benefits of not needing a cross-beam structure, making it suitable for carrying large project cargoes. When the Semper Fi is loaded to the maximum with containers, the wheelhouse can be hydraulically raised to ensure the visibility at the helm.

The use of high-strength AH36-steel, in the side decks and coamings, allowed for ten millimetre plating to be used where normally twelve millimetre plating would be used. This amounts to a total weight saving of 15 tons, or in other

With the main engines placed transversally, the engine room is very compact

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The compact jet thruster in the bow is electrically driven The wheelhouse monitors are placed behind a glass plate

Subcontractors and suppliers of equipmentfitted on board the Semper Fi - YN 1023

A.A. Vink, Sliedrecht : outfitting shipyardAll Pumps Holland, Nieuwland : pumpsBeerens, Werkendam : masts; wheelhouse stairsBlokland non-ferro, Sliedrecht : box coolers; oil coolers; expansion tanksBP Bunkerstation Papendrecht, Papendrecht : bunkering; various suppliesCaldic Technics, Rotterdam : Stamford alternator and shaftgeneratorCastrol Marine, Rotterdam : lube oilsCentraal Bureau voor de Rijn- en Binnenvaart(CBRB), Rotterdam : consultencyClimaLogic, Sliedrecht : airco and ventilation fansDiscom, Alblasserdam : silencersDockmarks, Zwijndrecht : signage; communication; websiteDP Chartering ( Danser/Pro-log), Zwijndrecht : freighterE.B.R., Lage Zwaluwe : wheelhouseEFM, Meppel : insuranceEMS, Alblasserdam : electrical installationGermanischer Lloyd Netherlands, Schiedam : classificationING Groningen, Groningen : financingJiskoot & Van Weel, Rotterdam : design & engineering; hull construction

managementMARIN, Wageningen : CFD calculations and tank testingMiron, Alblasserdam : sanitary installation; floor heatingNelf Marine Paints, Marrum : paintsPinta Nieuwburg Unisol, Ridderkerk : insulationVeth Propulsion, Papendrecht : Veth hybrid z-drives, Veth compact-jet

thruster, Scania main engines and gensets, VFDs, E-motors, exhaust treatment systems

Willemsen Interieurbouw &Scheepsbetimmering, Huissen : carpentryWijk Van, Werkendam : car crane; anchor chains; mooring

winches

high level of privacy and comfort as all crew members can cook to their own tastes.

ConclusionOoms took his time to develop the concept for the Semper Fi, and it shows. Every component on board was carefully considered for its cost, efficiency and weight. The end result is a fuel efficient inland barge with almost invisible exhaust fumes and a practical and spacious cargo hold. Ooms is wary of making bold predictions about projected fuel savings, but he has promised to make a comparison with the Carpe Diem, which has similar characteristics and operating profile. A subsidy from Agentschap NL was indispensable to give this prototype ship her green credentials and Ooms believes that in future vessels, the extra investment cost will be reduced to € 400,000 to € 600,000 for the same results.

Bruno Bouckaert

terms, an extra 15 tons of cargo can be shipped when water levels dictate the ship's maximum draught. Further weight reduction was achieved by cutting lightening holes in the steel structure wherever possible. For the structural design and the project management of the hull construction in Romania, Carpe Diem Shipping called on the naval architects of Jiskoot and Van Weel. For the outfitting, Ooms found an excellent location and workforce at A.A. Vink in Sliedrecht.

AccommodationThe interior construction was contracted to Willemsen Interieurbouw, who created a stylish modern interior with the input of Ooms' wife, Alice. The couple's own living quarters are in the aft and include a large space below (credit to the compact engine room), with washing room and space for entertainment. In the bow of the ship, two complete apartments with individual bathroom, bedroom and cooking corner, are provided for the rest of the crew. This arrangement gives everyone on board a

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