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Study and proposition for the modernization of the dredging fleet of the Grand Port Maritime de Nantes - Saint-Nazaire


The GPMNSN is owner of some dredging equipment to take care of its maintenance dredging. IMDC was asked to help them with the selection of the best dredging equipment to replace the cutter suction dredger (CSD) André Gendre. This new equipment had to be capable of taking over all of the maintenance dredging that up till now was done by the Andre Gendre.

IMDC was also asked to evaluate the impact of the proposed new equipment on the daily activities of other dredging equipment still in use in the port: would it cause a reduction of their operational hours or would it perhaps make their use superfluous?

IMDC realized the whole project in 4 phases :

Phase 1 : Identification of the specific port dredging needs.
A detailed description of the specific dredging needs for the port was given : which are the dredging zones? How is the disposal of the material organized ? Which volumes are we talking about? Which are the prevailing hydrodynamic conditions? Etc.

Phase 2 : Identification of all suitable dredging equipment to meet these needs.
First a thorough description of modern dredging equipment nowadays available on the market is given. Then each dredging zone is confronted with this list and the suitability of each of these dredgers is evaluated per dredging zone.  The "ideal" dredger per dredging zone is determined taking into account a series of quantitative and qualitative restrictions, first for each dredging zone individually, then for the whole of all dredging zones within the port actually maintained by the Andre Gendre.

Phase 3 : The definition of all possible feasible scenarios to meet these needs (taking into consideration the different options for disposal of the dredged material).
The previous phase showed that a dredger that is capable of dredging all the dredging zones in an optimal way does not exist. A choice has to be made between different technically feasible "solutions" proposed by IMDC. In this phase the evaluation is done taking into account only the technical restrictions (quantitative and qualitative requirements). In the next phase, a financial comparison is made between the most feasible options.

Phase 4 : Estimation of the costs of the most feasible scenarios.
Within this evaluation, both acquisition as exploitation costs are considered.  Exploitation or operational costs are split up in several components like personnel costs, maintenance and repairs, consumables, etc.
The estimations are based on the NIVAG standards and info gathered from different ship yards. The study was round off with a sensitivity analysis on the main influencing parameters like gasoil prices, personnel costs etc.

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