Windy shows data from 2 wave models: WAM from ECMWF and WAVEWATCH3 from NOAA. Do you check both of them?
These models have a medium resolution. So some local conditions of wind may give a worse sea state.
Depending where is your boating zone, Windy offers higher resolution Wind models which give you a better idea of expected waves height locally.
At the end, you must always crosscheck with official weather advisories at sea when you plan your trip.