Hi Guys. Thanks for your replies. Just some additional info; the boom of my unused sail is removed (I've only got one sail, and a few local sailors have told me to remove the boom - orientate the sail in the usual position on the ground, and then put the boom on the bottom of the sail to stop it blowing away - due to turbulence). Where I sail, inbetween the road and the beach are grassy dunes - no fences, no trees - no wind shallows. The Seabreeze is cross shore.
I was wondering if I could put the sail on the beach (face the mast foot into the wind as Mark_australia said, and put some sand on the bottom of the sail as ballast. Sand will naturally cover the sail anyway, as the beach turns into "rivers" of sand. However, I am a bit worried what this will do to the sail when sand goes to the mast sleeve. Am I able to get this sand out without rerigging it ?, if not will this sand damage the mast and mast sleeve ?.
Mark_Australia: the star pickets is a good suggestion... but sand will still end up covering the sail when she blows, so I might as well just do what I suggested above.
thewindmap: I only have 1 board ATM.
NotWal: What's a dog screw ?. Re: leaving sals in sun: The dilemma when sailing under/power powered is, should I rig the other sail ?. By the time you do that some days, you miss the window and the wind either returns to previous state or dies in the arse

I'm erring on leaving the unused sail in the car.
Ja