All coastal and offshore structures such as sea walls, break waters, oil platforms, etc, are directly or indirectly affected by waves. Also due to broad requirements of coastal engineering, knowledge of the magnitude and behavior of waves at site is an essential prerequisite for almost all activities in the ocean including planning, construction and operational harbor, offshore and coastal protection structure [1]. Instead of studying behavior of the marine structure prototypes in the presence of waves, it is usually preferable to use their small scale models in laboratories. One of the advantages of performing the model tests in the laboratories is that it provides necessary tools to study; wave energy effects near coastal structures, reflection and transmission phenomenon on break waters, hydrodynamic forces exerted on floating bodies, etc. It is therefore required that waves be generated with specific characteristics in laboratories. These waves are usually generated in towing tanks or wave basins, using a wave maker which is composed of an electro mechanical mechanism. Different types of wave makers include piston, flap, pneumatic, paddle, and plunger types. A plunger type wave maker is made of a solid submerged body which oscillates vertically into water surface. This vertical motion causes water displacement which in turn generates waves. The plunger cross section could be in different shapes. However, the most general shape is cylindrical or triangular ones [2]. The plunger type wave maker is easily
deployed in towing tanks for making high amplitude waves in deep waters. However, due to difficulties in its analytical solution, the theoretical studies on this type of wave maker have not been extensively explored. This paper is an effort made to obtain characteristics of a plunger type wave maker installed in the subsea research and development center (SRDC) of the Isfahan University of Technology (IUT). Detailed information about wave makers can be seen in reference number [3].