The orientation of a FPSO or similar using a swivel and turret system will depend on the resultant of wind and tide i.e. there will often be occasions when the wind can come from the rear of the vessel causing potential temperature increase or (less commonly) turbulence from the hot exhaust gases.
The problem with this scenario is that the bad orientation normally coincides with low wind velocities so that the increased temperature and low windspeed have a greater effect on power margins on approach and departure.
A similar scenario exists on storage tankers moored to SBM's. One solution often used is to permantly employ a tug vessel to choose the preferred orientation.
Trog