Maintenance policies for armour blocks are discussed to minimize total expected maintenance cost over target horizons. The amour block facility is subject to waves which occur at a homogeneous Poisson process, deterioration of the facility's performance occurs cumulatively. The broken facility is maintained immediately as corrective maintenance. This study proposes three kinds of maintenance models; repair level R1, block with minimal repair ,T and discrete k models. An optimal R1* to minimize the expected total maintenance cost in service period is discussed. Optimal time T* and the number of corrective maintenances k* are derived. Some numerical examples are given.
