The Grand Port Maritime de Marseille acquires a new multibeam system

Publié le 5 May 2021
Logo Grand Port Maritime de Marseille FOS
The mission & the problem
Strengthening multibeam survey capacities

The main sounding boat “Escandail” was commissioned in 2004 and was designed to use a multibeam echosounder and other high precision hydrographic measurement equipment. The need for a second, lighter but equally versatile boat quickly arose and the opportunity arose in 2007 to order a new speedboat.

The choice of a catamaran hull was made for reasons of navigation stability and interior space facilitating the movement of the crew, whose safety is increased. The powerful motorization of two 150hp outboard motors ensures endurance and range with moderate consumption. In February 2009, the hydrographic boat “Coustié” was delivered to the port of Fos, the Bathymetry Activity was thus equipped with a second modern and efficient boat.

Navette hydrographique Grand Port Maritime de Marseille
The initial missions of the hydrographic boat

This boat, however delivered without any specific bathymetric equipment, was from its arrival used for various missions:

  • Technical links for topography sessions,
  • Water and sediment samples,
  • Turbidity measurements,
  • Implementation of a towed lateral sounder and soundings with a single-beam sounder with a removable base.

The initial choice of a catamaran was also motivated by the possibility of installing a multibeam echosounder similar in technology to that of Escandail. This type of assembly had been observed in Anglo-Saxon manufacturers but the high cost of the transformation delayed this change.

Time for change

The decision to equip “Coustié” with a multibeam sounder was finally taken in 2017. Over these eight years, the technology of multibeam sounders, attitude centers and associated equipment making up bathymetric acquisition chains has greatly increased. progressed and their prices have become more affordable.

All these materials, while retaining their robustness and performance, tend to be lighter and more compact, and this is what was expected to equip the hydrographic cruiser. Newly planned works for Coustié are multibeam bathymetry in the depth range from 0.5m to 80m as well as the inspection of quayside walls and bathymetry in shallow depths.

Schéma installation navette hydrographique Grand Port Maritime de Marseille
The Grand Port Maritime de Marseille need

The description of the modifications to be made on the boat is very difficult to express because it involves drilling the hull in its center to create a central well in which a vertical telescopic support will be submerged, thus creating the support for the future multibeam sounder. All the modifications made should allow the boat to maintain its initial nautical qualities without changing its navigation category. In this sense, the inspection by the services of the “Ship Safety Center” will be decisive in the outcome of the project because beyond the simple supply of bathymetric equipment, the intervention of a shipyard to carry out the hull drilling. and the fixed installation of this whole structure turns out to be inevitable. The control and monitoring of the site by a maritime expert firm is also essential.

 

It is on all these points that the service is unusual because it combines high precision equipment and very specific know-how in shipbuilding with monitoring by a maritime expert firm associated with a control and final validation by the company. maritime administration. The contract will finally be awarded in summer 2020 and the CADDEN company in Nantes selected for the entire project thanks to the quality of the materials offered but also because of an extremely complete and detailed technical file. It will call on the company “Composit services” of Port Corbière for the work of modifying the hull and the maritime consulting firm Marc Emig for its recommendations and compliance with the rules of the art.

Navette hydrographique Grand Port Maritime de Marseille
The solution
Installation sondeurs multifaisceaux R2 sonic Grand Port Maritime de Marseille
A new multibeam echosounder

CADDEN has been distributing and installing bathymetry systems since 2003 and markets the range of sounder from the manufacturer R2Sonic. The chosen model will be the Sonic2022 which covers the frequency ranges 170 to 450kHz and has excellent background definition. Its limited weight allows it to meet the required telescopic pole mounting. The fineness of the beams and the high density of the measurements acquired are a major asset for dredging monitoring, inspection of submerged structures and docks.

The entire acquisition chain includes, in addition to the sounder, an SBG Systems Apogee-i inertial unit with integrated GNSS compass and RTK (Kinematic Real Time) and a Valeport Mini SVS hull speed probe integrated into the base, an acquisition PC, a radio modem for precise location, all of which is supplied with current regulated by a generator and an inverter.

Despite all the technical and administrative preparation upstream, the drilling of the hull was felt to be an irreversible stage of the project. The fabrication, integration and fixing of the central well was eagerly awaited by all involved.

The other essential element of the installation was the metal tubular structure of the telescopic pole and its base which had to be fixed at five points on different surfaces of the deck and the cap of the boat.

« We were still a long way from the first polls but that’s when the project took shape before our eyes and generated a lot of enthusiasm within the team. », Confides Henri-Georges Gaillard, Hydrographer at the Grand Port Maritime de Marseille (GPMM). »

Installation sondeurs multifaisceaux Grand Port Maritime de Marseille
Levés bathymétriques Grand Port Maritime de Marseille

Shortly before the end of the shipyard’s intervention in Corbière, the engineer responsible for the file within the CADDEN company intervened on site to install and fix the various devices in the acquisition chain, adapt the cable lengths. and their passages through the partitions, connect and test the operation of the assembly. August 03 Coustié is launched.

Sea trials, calibration of the acquisition system and training of hydrographers on the new equipment will take place a few weeks later, still supervised by the CADDEN engineer. September 22 marks the first survey of Coustié with its new bathymetric channel.

The decision to equip “Coustié” with a multibeam sounder was finally taken in 2017. Over these eight years, the technology of multibeam sounders, attitude centers and associated equipment making up bathymetric acquisition chains has greatly increased. progressed and their prices have become more affordable.

All these materials, while retaining their robustness and performance, tend to be lighter and more compact, and this is what was expected to equip the hydrographic cruiser. Newly planned works for Coustié are multibeam bathymetry in the depth range from 0.5m to 80m as well as the inspection of quayside walls and bathymetry in shallow depths.

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