The Structural Design of Wave Energy Devices (SDWED) project, led by Aalborg University, has had an amazing output of free software including advanced hydrodynamic models, wave to wire models, and a spectral fatigue model:

www.sdwed.civil.aau.dk/software/

Also, at the bottom of that page is a list many other free software products.

“The Structural Design of Wave Energy Devices project (SDWED) 2010-2014 is an international research alliance supported by the Danish Council for Strategic Research. The project is a five-year endeavour to harness the energy potential in wave energy at competitive costs.” (www.sdwed.civil.aau.dk/)