If you ever wondered how big the seas get for a given wind speed, or how the heights are statistically distributed, or how fast the waves are moving, or how long does it take the seas to build, or the influence of water depth on sea state, or how big waves develop from little ones, or how waves turn into swells when the wind dies... or any other question at all about waves, swells, ripples, or surf, or the interaction between current and waves, then these books provide the definitive answers. Essentially all other references on waves ultimately refer back to these studies.
An introduction to Sea State Forecasting
Wind Waves at Sea Breakers and Surf (Publication 602)
Observing and Forecasting Ocean Waves (Publication 603)
Bowditch on Sea State (Chapters 31-33)
Supporting OS: Windows 98, NT, ME, 2000, XP, Vista