What must vessels do if both are sailing with the wind on the same side?

When two sailing vessels have the wind on the same side, the rules of navigation dictate that the vessel that is to windward must keep out of the way of the vessel to leeward. This is established in the International Regulations for Preventing Collisions at Sea (COLREGs), specifically in Rule 12, which addresses sailing vessels. The rationale behind this guideline is that the windward vessel has the potential to interfere with the leeward vessel's course and wind freedom, making it crucial for the windward vessel to maneuver out of the way to prevent collisions.

In this scenario, it is not necessary for both vessels to stop, nor does the length of the vessels play a role in determining which must yield in these circumstances. The focus is solely on their positions relative to the wind direction, making the distinction clear and straightforward for navigational safety.