The purpose of this paper is to present a semi-analytic model designed to optimize tidal farm layouts bymaximizing the mechanical power production. A meta-heuristics method is used to find the turbineplacement which minimizes the flow interaction between the turbines. The velocities in the wakes of tur-bines are simulated with an analytic model. The methodology is first applied to idealized cases: constantcurrent magnitude and direction, and flow aligned with the turbines. Those preliminary tests permit totest the consistency of the results. In particular, they show that the optimal density of the devices growswith increasing turbulent intensities or increasing upstream velocity magnitude. The methodology isthen applied to a site located in the Alderney Race (Raz Blanchard in French), situated between theAlderney Island and La Hague Cape (France). The results show that the optimal placement is influencedby the asymmetry of the tidal current and that the best layout is strongly dependent on the directionalspreading of the current with respect to the predominant direction.