Flensburger Schiffbau-Gesellschaft (FSG) shipyard in Germany is speeding up the production of ro-ros by making use of sophisticated design tools. In 2001 the yard achieved the ShipPax Award for its “outstanding ro-ro concept” on the new vessel UND Ege, one of six sister ships built for Turkish shipowner UND.

New solutions
Says Wolfgang Bühr, head of design and development at FSG, By adding a simple steel deck we managed to increase capacity from 2,700 to 3,200 lane metres, an additional investment that has turned out to be less expensive than estimated.

Ships of this type have few or no transverse bulkheads, which reduces the racking stiffness. It is a challenge for the yard to design a proper connection between slender mainframe structure and the rigid ramp structure. FSG performed Finite Element (FE) analysis for these areas, which was verified by DNV.

The 4-deck version was specified with one design draft, enabling the designers to optimise the hullform at that particular draft. A stern trim wedge has been fitted as a result, boosting the speed by about 1/2 knot compared to earlier 3-deck vessels.

Doubled throughput
FSG spends more than 10% of its turnover on research and development (R&D) annually. 25 engineers are permanently engaged on R&D projects inhouse or in close cooperation with universities, developing new design tools and improving productivity. They have developed low-cost automation tools such as welding tractor machines instead of standardised welding robots, which have increased efficiency and doubled throughput during the past ten years. They have resulted in a 50 % reduction of individual operations. One production line has reduced manpower from 24 to 14 with the same throughput.

Building vessels based on a risk-based approach should be a prime goal for all involved in construction, says Bühr. It is not enough to follow the classification rules only. We have to extend their scope and take a look at the consequences to find out how to handle them. It is a matter of optimising the whole system. A good example is a rudder type utilised by FSG, but not completely covered by the DNV Rules. Consequently some modifications had to be made to the rule formulas, after thorough discussion between FSG and DNV.

FSG is now able to simulate the whole steel production process with original design data up to three months before building starts. This has a two-sided effect, according to Bühr. New layouts can be tested before any investments are finalised; also employees are involved in the early stages of simulation, which increases their familiarisation with the product before building starts. FSG has recently commenced simulating the behaviour of passsengers evacuating a ship. The studies are expected to be finalised by the end of this year.

Future 5-decker
FSG is now in the process of designing a new 5-trailer deck concept for ro-ro vessels. Arrangement of the deck heights and ramp layout makes possible simultaneous loading and unloading of four different cargo areas. Simulation studies have shown that the same amount of cargo can be handled via each ramp. The harbour turn-around times have thus been minimised, despite the amount of cargo to be handled. A completely new concept of internal and external watertight integrity ensures and extremely high safety standard. The new 14,100 dwt ro-ros have a capacity of 6,100 lane metres. Their operating speed is 23 knots.