Sun and wind can complement each other, but I wouldn't choose a wind turbine just because "it's often windy on the water." The decisive factor is the wind the turbine actually receives where it is mounted.
Solar panels
Solar panels have no moving parts and are easy to integrate into a system with MPPT and a battery. On the other hand, production drops in shade and during the darker part of the year.
Wind generator
A wind generator can provide energy when there is sufficient wind – even when the sun isn't shining. However, performance is highly dependent on wind speed and turbulence, and installation, vibrations, and noise must be taken into account.
Both
On a year-round boat, the combination can be interesting because production comes from two different sources. However, each charging source must be regulated correctly for the battery, and the battery's maximum permitted total charging current must be respected.
What I want to know before purchasing
- Where the boat is located most of the time: open water or sheltered harbor.
- Where the turbine can be mounted securely and with clear airflow.
- Your actual daily consumption.
- What other charging sources you have.
- Battery type and maximum charging current.