It looks like it could be 24 nm according to the "
Contiguous zone" at this site:
http://www.ag.gov.au/www/agd/agd.nsf...riesandZones#2
...With the Jessica Watson vs ship thingy, I emit an audible groan every time I hear it mentioned that the lass collided with the ship. In actual fact the ship collided with her. The COLREGS are the rules of the sea, and nowhere in the COLREGS does it state that "the smaller vessel unconditionally gives way to the larger vessel", This would be akin to the road rules having a "rule" that says you have to stop at a green light to give way to the truck approaching the red light because he is "bigger and less manouverable" then you.
No matter how big the ship, the mere size of it alone does not restrict it's ability to manouver. The whole "restricted in ability to manouver" bit is referring to
any vessels constrained by draught (as in if they change course, they run aground) or by some operation e.g. dredging, fishing or towing that, well, restricts their ability to manouver.
Some might be surprised that the COLREGS do, in fact, have a rule that states that power gives way to sail and other non motorised powered vessels unconditional to the relative sizes of the vessels. It also states that a vessel that has the right of way must "stand on". To stand on means to maintain course. Jessica Watson's boat was equipped with - from what i can gather and I could be wrong - radar and AIS so it could conceivably come out in the wash that she was maintaining lookout and simply standing on. Her one and only mistake being to leave it too late to take action to avoid a collision - quite a feasible scenario considering that at night it is extremely difficult to estimate distance and heading of vessels in open water by eye.
It may also be that Jessica didn't maintain a lookout. If this is the case neither did the ship's watch and they also failed to give way.