Originally Posted by fud
I have to confess that I know zero about ISAF racing rules, but I do want to comment on one thing you mentioned.
That is not correct. When a sailboat is over taking a powerboat (even though this may not happen all that often) the power boat is the stand-on vessel and the sailboat is the give-way. I'm being picky, but also if the sailboat has the engine on (or perhaps in gear?) even if his sails are up (motor sailing) the sailboat is considered a powerboat and must follow those rules. Hope you don't mind my critique. The more I post here I'm sure you will get an opportunity to return the favor. :-)
I agree that if the sailboat is overtaking from astern, it should try to keep clear. But this is a little complicated. If you're in a powerboat and a sailboat under sail is holding a steady course and you choose to steer right in front of it, you're not giving way to the burdened vessel. In many situations like this, it's not a case of the sailboat is moving faster and following the powerboat dead astern, in which case the sailboat should go around the powerboat. Many times the two boats are converging, and it's up to the powerboat to recognize that convergence as the gap between them closes.
Your complication of the sailboat under power is right in that the sailboat at that point is no longer a sailboat (even if one or more sails are up). If you start turning on your motor while under sail, you're just another powerboat, which includes the fact that being on starboard is meaningless where other sailboats are concerned.
Good to chat about this.