It's pretty much the same as wind turbines on land, the difference is that
1. Installing foundations offshore is more complicated and more expensive than installing foundations on land
3 The air at sea is very humid, salty and corrosive. Wind turbine equipment requires special treatment. -treatment against corrosion. Resists strong corrosion in sea air.
So we can say that the cost of offshore wind turbines is higher than that of onshore wind turbines. This is also the reason for the unit capacity of offshore. wind turbines need to be large, which can reduce foundation and lifting costs