There is a huge range of lengths and displacements among the boats.
The bigger the sail area the bigger the motors you will need to control them and the higher the power requirements. it would be good if the sails were PV and could provide power.
At least one boat is using ultrasonics for collision avoidance. I am not sure how well that would work in a windy wet environment but it sounds more practical for an arduino to process than some kind of vision system.