SA legislation - the relevant bits
Division 4—Rules of special application to recreational vessels
169—Personal flotation devices to be worn on certain recreational vessels
(1) Each occupant of—
(a) a vessel (other than a surfboard, surf ski or racing shell) that can only carry the operator and no other person; or
(b) a surfboard, surf ski or similar vessel that is being operated in inland waters; or
(c) a sailboard or kiteboard; or
must, at all times while the vessel is underway, wear—
(j) in the case of a sailboard or kiteboard—
(i) being operated more than 400 m from the shore—
(A) before 1 June 2010—a PFD Type 1, PFD Type 2 or PFD Type 3;
(B) on or after 1 June 2010—a PFD Type 1; or
(ii) being operated not more than 400 m from the shore—a PFD Type 1, PFD Type 2 or PFD Type 3;
Maximum penalty: $1 250.
Expiation fee: $160.
Stolen from a windsurfing post, If the vest isnt PFD rated it wont pass but hopefully the inspector will go yep thats a PFD and let you go .
Just like all government regulations very easy to interpret