no offence to James, but I'd have said sailing a Hobie 16 singlehanded with only a couple of years sailing behind you, and at only 11.5 stone, could land you in trouble.
At this weight you'll struggle to get the boat back on it's feet if you capsize, and the hull design doesn't exactly discourage falling over. (obviously whether you're on a lake or the sea has a big bearing on the dangers)
As much as I'm a fan of H16's I'd recommend the Dart 15 - not as fast, but much easier to right on your own - and you can pull it apart and chuck it on top of the car. It's raced in both one-up and two-up mode, though I think they use a larger rig (Sprint?) for two-up racing..
There are a few active racing fleets around the country and I know they gear their Nationals as much to cruisers as racers.
Sorry to betray Hobie 16's like this ! (I shall go home and apologise to mine now!)