20.3 A boat moving astern by backing a sail shall keep clear of one that is not.
The key phrase there is "by backing a sail." If you can back up without backing a sail, as can be done with a lot of boats, you still have rights over the boats behind you, because they are still considered overtaking boats.
Am I wrong? I can back up my boat forever with the sail just loose and weathervaning.
No Mary, you are not wrong. If you are moving astern WITHOUT backwinding a sail, you maintain your rights. Watch match racing starts(yes, I know match racing rules are different, but not in this case) and sooner or later, you'll see what's called the "dial-up", where both boats go head-to-wind and often start drifting backwards. Just because they're going backwards doesn't mean they lose their rights - the leeward boat remains leeward boat and the windward boat has to keep clear. In one of the recent Americas Cup races, the boats were actually sailing backwards side-by-side at over 6 knots. That was faster than the umpire boat could motor backwards. It had to turn around in order to keep out of their way.
Regards,
Eric
