Efficient vessels in series

The European Community?s phase out of shipyards subsidies by the end of next year for orders received up to the end of 2000 led, understandably, to an orders boom in 2000. That boom left most German yards with an order backlog up to the end of 2003. Some have orders in hand up to the end of 2004.

One yard that has taken notable advantage of the situation is Flensburger. The yard, located near Hamburg close to the Danish border and just north of the Baltic entrance to the Kiel canal, has used the subsidies of the past 10 years for facility investments of about 843 million ($40.6 million) and for R&D projects worth about 830 million.

At the beginning of 2002 the yard?s order backlog contained two roro vessels for the Turkish owner UND Ro-Ro (four having previously been delivered in 2000 and 2001), four vessels for the Danish owner DFDS Tor Line and four for the British consortium AWSR, UK Sealift. Significantly, these ships are all of a similar design. According to Flensburger manager Fred Garbe, their great advantage is their low fuel consumption compared with similar vessels of the same size and speed; savings for owners, considering a service time of 20 years, amount to 85 million he says.

Garbe says this string of newbuildings amounts in effect to “series production”, which has resulted in savings of time and money in production. A series of six vessels results in unit cost savings of between 20 and 30% compared to one-off building, Garbe calculates.

Up to now the production program has only covered roro cargo ferries. However the yard has a 26-knot ropax ferry design for 2,000 passengers to make six- to seven-hour crossings in the Mediterranean. Part of the concept is an amphitheatre at the stern for entertainment of the passengers just as on a cruise liner. For the next three to four years, according to Garbe, there will be a demand of 20 to 30 ferries for operations in the Mediterranean and in the Baltic Sea. His goal is that Flensburger shall deliver at least six of them.

R&D activities

Of the staff of 600 persons about 25 work exclusively on R&D projects, either concerning product development or the optimisation of production processes. This is the background for the development of the roro vessel series 2700, 3200 and 3900 as well as the ropax vessel series 2000, 400, 100/400, 100 and 1500.

Up to 1995, optimising hull forms was a business for institutes like Hamburg Ship Model Basin with time-consuming and expensive model tests. Flensburger started in 1996 to develop and adapt computerised fluid dynamics (CFD). From 1997 on, the first approach for all projects worked on and all vessels built has been to use CFD simulation to obtain a relatively precise set of dimensions for the following model test in the basin. Flensburger has several simulation tools, most of them of its own development. Basic tools come from the universities and are adapted to and integrated into Flensburger?s simulation network.

As far as production processes are concerned the task is to reduce on a long-term basis production hours to about one third of the time required in 1992 for a specific vessel. Today, 10 years later, a 45% reduction has been achieved.

The simulation of production processes is the decisive instrument to decrease working hours and improve equipment supply. In future Flensburger intends to simulate the production of any new vessel three times before actual construction.

Beyond physical phenomenon and production processes the handling of ships can also be simulated by Flensburger. This applies for instance to loading and unloading of a ship.

Technical details of roro vessels and orders

The Turkish owner RoRo Isletmeleri AS, Istanbul, ordered from Flensburger six Ro-Ro vessels, with the first order covering two three-deck vessels of type 2700 and with the second covering four four-deck vessels of type 3200. The latter are developments of the 2700 class with a fourth deck between wheelhouse and bow. These vessels are destined to serve the Istanbul-Trieste route. The 22,900g/ 14,268dwt type 2700 vessels have a capacity of 2,640 lane metres, corresponding to 180 trailers (13.6m); the 26,700g/9,830dwt type 3200 vessels have 3,214 lane metres for 210 trailers. Both types are 193m in length.

For a service speed of 21.6 knots type 2700 requires a total power of 16,200kW. With the step from type 2700 to 3200 the hull could be improved so that the service speed reached 22.1 knots (+0.5 knots) with the same propulsion power.

The British consortium AWSR, Andrew Weir Shipping, has ordered six modified type 2700 vessels to be operated under charter by the British Ministry of Defence; two of the six vessels will be built at Harland & Wolff at Belfast.

The vessels for AWSR are nearly identical in appearance to the UND vessels. Their modifications include strengthened hull and classification for ice transit, strengthened decks to carry tanks, additional sideports for loading and unloading in harbours not prepared for roro vessels, a 40t crane for loading and unloading deck cargo as well as a modified stern ramp. For this application the service speed is reduced to 18 knots. The vessels, which are Lloyd?s Register-classed, will not be equipped with weapons.

For logistic reasons the equipment onboard all six vessels will be identical. Thus the entire procurement is in the hands of Flensburger acting as an agent for Harland & Wolff.

For the Danish owner DFDS Tor Line the type 3900 was developed within the series, featuring four full decks with 3,831 lane metres and a service speed of 23 knots. This type is about 7m longer than the 2700 and 3200, having dimensions of 10,500 dwt and 30,800g. Flensburger has to date received from Tor Line orders for four type 3900 vessels plus one option. They were negotiated against strong competition from China. A competitive advantage for Flensburger is, thanks to CFD and other simulation tools, its ability to present a detailed offer within four weeks, including a full design with all hull lines and a virtual vessel presentation.

Power installed and fuel consumption

The level to which the hulls and the propulsion systems are optimised is demonstrated by relating the power installed to the tonnage in dwt. The 2700 type reaches a value of 1.135kW/dwt, the 3200 just 1.648kW/dwt and the 3900 a value of 1.911kW/dwt. It must be taken into account that these specific figures belong to vessels with different service speeds. Comparable vessels of other design show values between 1.85 and 2.1kW/dwt. As the type 3900 has a 7% higher service speed its value does not fit in this comparison. But the comparison of the fuel consumption shows that the type 3900 is a very competitive vessel.

Types 2700 and 3200 are equipped with two nine-cylinder MaK series 43 engines with an output of 8,100 kW each. The service speed of 21.6 knots is reached with 90% MCR and engaged shaft generators of about 800kW each. Under these conditions the fuel consumption is 61.2t per day. Type 3900, equipped with a MAN B&W nine-cylinder 60 MC-C two-stroke (MCR 20,070kW), consumes under the same conditions only 73.7t per day.