Except where Rules 9, 10, and 13 otherwise require:

(a) A power-driven vessel underway shall keep out of the way of:

1. a vessel not under command;
2. a vessel restricted in her ability to maneuver;
3. a vessel engaged in fishing;
4. a sailing vessel.

(b) A sailing vessel underway shall keep out of the way of:

1. a vessel not under command;
2. a vessel restricted in her ability to maneuver;
3. a vessel engaged in fishing.

US Coast Guard Navigation Center

So we in a sailboat have the right of way under ANY tack against a maneuverable powerboat under way. YES, I agree that it doesn't mean we should always assume that stupid poweboaters will give way. In fact, I assume just the opposite. But you can't avoid what you can't see. If it were another sailing vessel, since we were on port tack, we would have had to give way. But we would have seen it at some point. It's not like Danny wasn't looking downwind under the boom at ALL! The Bayliner was traveling at close to 40mph when it hit us. It came up on us so fast and so sudden there was no way we could've avoided or even maneuvered the Hobie fast enough to get out of the way.