I start by saying I really dislike Jet Ski's, they simply have no attraction for me at all, and unfortunaly they do seem to attract a certain type of individual.
But in saying that, seeing you said they were 100m from shore, unless there was someone swimming in the netted area and they didn't come with-in 60m of any windsurfer they might not have actually doing anything wrong (however that can always be interpreted many ways).
It's also worth noting that accoring to Maratime NSW some of the same rules apply to windsurfers:
Sailboarding/Kitesurfing
Sailboarding (sometimes referred to as windsurfing) and kitesurfing (sometimes referred to as kiteboarding) are surface water sports that combine elements of surfing with sailing and kiting, harnessing the power of the wind.
Both sailboards and kiteboards are classified as vessels and therefore come under NSW marine legislation.
Distance off
When travelling at 10 knots or more, sailboarders/ kitesurfers and their equipment, including kite and lines, must:
•Maintain a minimum distance of 60m from any persons or non-powered vessels or 30m from powered vessels and any objects in the water or, if that is not possible, a safe distance.
•Stay out of a designated swimming zone.
This means everytime you pass close by another sailor and you are on the plane you are actually breaking the law (ie, traveling greater than 10 knots with-in 60m of an unpowered vessel).
The above rule seems silly to us, and I have never heard of it upheld. Just think of the number of times you have sailed close to a mate, or sailed past a guy who has fallen and is in the water. Just pointing this out because sometimes you do need to be careful what you wish for in chasing down these guys, as it could come back to bite you.
But I'm assuming they would focus on the harbour, not Botany Bay.
