The development of risks prevention plans frequently causes lively debates between state services (which conduct risks prevention plans and prior hazards studies) and relevant territorial authorities. The development of coastal risks prevention plans, identified as priorities after Xynthia storm in 2010, also faced hard difficulties. Debates mostly concerned coastal hazards mapping process, realized before the plans which strongly depend of them. A questionnaire survey of state services focuses on around sixty coastal hazards studies, concerning coastal flooding, coastline recession and sand dunes migration. The results define territories characteristics (current issues in territory and future territorial development), technical studies characteristics, project management and dialogue process between stakeholders. Chi-square tests of independence highlight major causes to encountered difficulties during dialogue process about coastal hazards mapping process. Current issues in territory don’t generate difficulties. However, territories with a high development and where prevention plans could bring constraints are places of conflicts about coastal hazards maps. Encountered difficulties during hazards mapping participatory process is also correlated to the complexity level of studies