divergence
 

I tried to calculate the floating yacht hull. The velocity of a yacht was 1m/s +y, the flow of a current was 0.1m/s -y, wind 5m/s +y. calculation converged in this case. If I increased velocity of the hull, the calculation would diverge, eventhou the critical velocity of certain yacht was 3m/s (Fr<1). Anz clue? thanks