The scientific community's interest in the impact of underwater noise on marine wildlife [39] has brought attention to these issues. In fact, we now know that the underwater noise produced by industrial operations (such as dredging or pile-driving) has a negative impact on marine biodiversity [38].

Some companies have therefore decided to find solutions to miti-gate these problems, such as Greenov, which is developing a noise and turbidity mitigation system called SSQ (SubSea Quieter). This system consists of inflatable panels that encircle the area of operation and attenuate underwater noise. As part of the development of this technology, which is still at the study stage, a project has been set up with the Port of Matane to create a cuboid-shaped SSQ that would not use ballast to develop the panels on the seabed (unlike conventional SSQs) but rigid posts that would counter the buoyancy of the panels with the weight of the barge.

The purpose of this SSQ would be to attenuate underwater noise and prevent the propagation of turbidity in the water during dredging operations in the port of Matane. My internship is part of this project, and the mission is to develop the struc-ture of this SSQ. In the context of this thesis, the focus was on the development of the system that will keep the SSQ panels anchored at the bottom of the water. The development of this system was carried out in several stages:-Selection of a technical solution.

-Desing of the selected solution.

-Material selection.

-Study of the manufacturing methods.

Firstly, for the selection of the technical solution, a functional analysis of the system was carried out in order to obtain selection criteria. Different solutions were found by different members of the SSQ team. A decision table was created to compare these solutions against the criteria. The chosen solution is a telescopic pole system that deploys using its own weight and locks in the extended position by rotating the smaller tube relative to the larger tube.

Following this, calculations of the forces the system will undergo due to the current and the buoyancy of the panels were carried out to design the system. This led to the design of two different versions of the system, using the software Inventor. In the first version, a Yield strength of 200MPa was assumed and some manufacturing constraints were neglected. In the second version, which was produced after the materials had been selected, a yield strength of 500 MPa was taken into account, and manufacturing constraints were better taken into account.In conjunction with the design phase, we carried out a study of the different types of corrosion that can affect the operation of our system.

This was followed by a study of the different materials or coatings that can resist these corrosion problems. Criteria were then agreed with other members of the SSQ team, with the aim of creating a decision table in which the criteria were compared with the materials selected during the study of material solutions.

The chosen material is duplex stainless steel.Finally, interest focused on the manufacture of the various parts of the system. The analysis showed that the extrusion process for the tubes forming the telescopic posts is intricate andiiicostly. Based on this manufacturing evaluation, it was determined that Gas Metal Arc Weld-ing (GMAW) with pulsed transfer mode is the most appropriate welding technology for our system.

Even if the technical solution won't necessarily be the one chosen for the future, the work carried out is nonetheless useful. Indeed, the criteria, methods and knowledge gathered for this study will contribute to the realization of the project.