www.imdb.com/title/tt0092220/The ultimate mainstream windsurfing movie made locally in the eighties, all about an aspiring competitive sailor (Tom "man-from-Snowy-river" Burlinson). I've posted my fave scene from it before, but to recap...
[spoiler alert!]
Hero running late for sailing comp in the final act. With his windsurfer tied on top his kingswood, he charges for the punt; if he misses it he misses the comp. Punt starts to pull away from shore, hero guns it and jumps car to try and make punt. Slow mo' of car gliding (in a kingswood way) thru the air toward the punt. Will he make it?
No, he won't.
Car sinks into water, with distressed onlookers getting worried. Suddenly, out of the water pops the hero on his fully rigged windsurfer and he's sailing off to make the competition.
Well, that's how I recall it anyway. Based on a true story I think...<cough cough>
[edit: looking a bit closer it also had a young Nic Kidman in it, circa "BMX Bandit" era!]