Ellen MacArthur wrote:

A little sailboat with no motor is on the starboard tack catching up with another
little sailboat with no motor on the starboard tack. The one catching up is going
on a course of 180 degrees. The one getting caught is going 208 degrees.

Which one has to change course if it looks like they're going to hit each other?

Your questions are meaningless unles you specify whether the boats are
racing or not. The Racing Rules of Sailing often give quite different
answers than ColRegs et. al.

Basically, unless you're racing, there is no reason to ever get that
close to another boat and any collision is most likely the result of
*both* skippers being incompetent.

//Walt