Peeps,
you need to read the small print, literally.
The reference is in relation to
offshore kite and windsurfers
It is a requirement that lifejackets are worn when operating more than 400 metres offshore in unprotected waters. This lifejacket can be a level 50S or higher.
Not sure how often you're 400m offshore, however, if you want the specific details go here:
www.transport.wa.gov.au/imarine/kite-and-windsurfing.asp