In accurate modelling one would need to consider apparent wind, wave conditions, currents, drifting of the vessel, heeling, the hull type of the vessel, the amount of rudder is given to the vessel to keep it on it's course, effect of other vessel near by etc.
Most of these parameters interact with each other.
* https://en.wikipedia.org/wiki/Forces_on_sails
In accurate modelling one would need to consider apparent wind, wave conditions, currents, drifting of the vessel, heeling, the hull type of the vessel, the amount of rudder is given to the vessel to keep it on it's course, effect of other vessel near by etc.
Most of these parameters interact with each other.
A complex problem I would say.