This paper experimentally investigated motions and loads characteristics of an attenuator type wave energy converter (AWEC) in longitudinal waves. The AWEC model consists of a set of cylindrical floats linked by two-degree-of-freedom joints. The power take-off (PTO) system of the AWEC model is a linear spring and damper system. Several conditions of the PTO system, such as power production conditions and fault conditions, were tested by the tank test. From the test results, response amplitude of the joint angle between cylindrical floats changes with the PTO system conditions both in regular and in irregular waves. As the load characteristics acting on the joints were affected by the PTO system conditions, it is important for the safety assessments of the AWEC to consider the conditions of the PTO system. The AWEC's simulation model based on a commercial code, the Orcaflex, was constructed and the simulated results were compared to the measured ones in regular waves. The model reasonably explained measured motions for each tested PTO conditions and measured loads on the AWEC if the PTO system was set to the power production condition or the fault condition that the joints were free to rotate.
