Integration of a Bottom-Up Production Cost Model in LBR-5 Optimization Tool

The LBR-5 software allows the optimization of ship structures following different objectives as the
highest inertia, least weight and/or least cost. The interest of European shipyards to optimize the ship
structure is basically related to the production cost and mainly to the labor cost. In order to increase
the quality of cost estimation, a bottom-up module has been developed by University of Liege in
partnership with AKERYARDS France. This module has been validated on different types of ships
(LNG, Cruise Vessels, Fast Ferry) and integrated in the LBR-5 optimization process. The bottom-up
cost module has two important goals. The first one is to estimate accurately the labor cost of a given
ship structure taking into account the production breakdown, the block splitting sequence and all the
individual operations required by the fabrication process. The second one is to compute properly the
sensitivities of the design objective (construction cost) related to the design variables (scantlings).
The paper also presents the results of a validation test on a large passenger vessel. The effect of the
bottom-up cost module on the optimal scantling and on the cost gain is highlighted through a
comparison with the results obtained using a basic cost module.