Power calculations
The 504 wind turbine outputs 80 Watts peak so will output the following: 80W/12V = 6.66Amps (Turbine output - peak
If you had a standard 100Ah battery in your yacht, this wind charger would have it charged from flat in around 100Ah x 80% = 80Ah so, 80Ah/6.66Amps = 12 Hours minimum.
Obviously your little turbine wouldn't be on peak output all the time so this time given is the best case scenario. Realistically you'd expect the turbine to have charged the battery over a 48 hour period (taking into consideration the wind is not always available).