Save Our Shipwrecks – SOS

Thousands of wrecks dating back to the industrial revolution (19th century) and 20th century conflicts lie along the French coast and form, over time, real artificial reefs. In addition to their intrinsic heritage value, they have a strong economic appeal on the one hand for diving (historical relics and their specific biodiversity), and on the other hand for the economic sector of fishing which finds nearby fish resources. However, these wrecks degrade under the effect of corrosion, severely modifying these ecosystems. These degradations are not only a risk for divers but can also be the source of pollutant release with dramatic consequences for the preservation of the marine environment. Thus the SOS (Save Our Shipwrecks) project aims to preserve the immersed heritage by cathodic protection (PC) treatments. It groups together 2 research laboratories specialized in corrosion and microbiology, the NIMBE / LAPA and the IPREM, as well as the DRASSM, in charge of research in underwater archeology and A-CORROS, company specialized in PC and conservation. heritage. This will be based on the study of two shipwrecks that will serve as in situ laboratories and have been selected for their historical interest, condition and location. Indeed, they are located in two environments (Atlantic-Channel and Mediterranean sea) with different characteristics. The project will be based on four axis of study. The first concerns the general characterization of shipwrecks, a step required to diagnose their initial state of corrosion and the sizing of the PC. In this area will be developed and used by the company A-CORROS an innovative underwater diagnostic tool capable of simultaneously measuring the corrosion potential and the residual thickness of metal. 3D photogrammetry will also be used for the virtual reconstruction of wrecks. The second axis will focus on the study of corrosion mechanisms with and without PC on corroded systems in the short (coupons installed in situ) and long term (samples of wrecks). Samples will be taken at different times for multi-scale characterization using complementary techniques (from macro to nanometer) corrosion products, formed deposits as well as microbial diversity. Similarly, samples will be characterized to describe facies evolution for different PC protocols. The interactions between biological colonization and PC will be studied, as well as the effect of the release of corroded metals and PC anode components. The results at the wreckage scale as well as the corrosion processes obtained in axes 1 and 2 are thus crucial to recommend the optimal PC treatment that will be implemented in axis 3 of the project on both wrecks. In this axis, at different deadlines, the global studies implemented in axis 1 as well as the characterization of new samples such as those carried out in axis 2 will then be conducted again in order to determine the evolution of these systems under PC on the real scale. All the results will feed into axis 4 actions aimed at the recognition of the immersed heritage by the public and at the awareness of protection. This project will have direct spin-offs in the areas of cultural and historical heritage, tourism, fishing and beyond for the protection of metal structures in the marine environment.