Sailboat. A PWC, or personal watercraft, is the give way vessel to any sailboat. In the US, a PWC refers to any small powerboat less than 13 feet in length. As such, it is a powerboat and must give way to all sailboats.
A sailboat and a PWC are meeting head-on. Which one is the stand-on vessel?
When a sailboat overtakes a powerboat, the powerboat is the stand-on vessel. (Ref: SB-29)
Powerboat
When a sailboat overtakes a powerboat, the powerboat is the stand-on vessel. (Ref: SB-29)
When a sailboat overtakes a powerboat, the powerboat is the stand-on vessel. (Ref: SB-29)
When it's the least maneuverable vessel in the encounter.
The question should be "When is the sailboat the stand-on vessel...? The answer is if the sailboat has an engine and if it is in operation, the sailboat is treated as a power boat in determining stand-on status. The right-of-way would then follow the rules for power boats.
When a sailing vessel and a pwc are meeting head on the sailing vessel is the stand on vessel.
power boat
When there is a danger of collision, the "stand-on" vessel is the one that must maintain its course while the other must take avoiding action. Sailboats usually are the stand-on vessel when meeting a power-driven vessel, even if that vessel is another sailboat (if its engine is powering the boat, and regardless of whether its sails are raised or not). There are exceptions: if the power-driven vessel is "working," such as a fishing boat dragging nets, or the power-driven vessel is confined to a narrow channel due to its draft, then the sailboat must stay out of the way, by altering course if necessary. If a collision is imminent and the other vessel shows no signs of altering course, then the sailboat should take whatever course is necessary to avoid it.
When it is being overtaken
When a sail boat overtakes a power boat the power boat is the stand on vessel.