Aren't all ships partly powered by wave energy if they're facing the right way?
There’s ways to trick and gain forward speed from waves, by basically picking a wave that’s high enough and continually sliding down on the front - Surfers for example. But that only works if your object is substantially smaller than the wave in question - which is sort of impossible for ships.
A boat can start surfing once the waterline fits on one face of a wave, so <1/2 wavelength. So a 70m tug just needs a 200m long wave. Mind you, those waves could be 30m tall and breaking over you :-O. So not impossible, but I'm not eager to try it.
https://www.passagemaker.com/lifestyle/freaks-of-nature-rogu...
The wave-glider is much more practical.