Thank you Rosie for taking me out in your National 12 today. Light winds, so I wanted to learn how to 'roll tack'. The crew (that's me) hop over to windward just before the tack and lean the boat over until you see, or feel, the lake lapping on the gunwales. This gets the boat to turn to windward without having to push the back round with the rudder - this avoids drag. The boss (Rosie) tacks and then climbs up the boat, flattening it just before it's time for a swim. This climbing provides the thrust which projects the boat forwards; the sails are set, the air is pushed to the back of the sails, we go forward. Simple.
However, with a crew of little faith, and a cold November lake, Rosie had a job getting me to roll the boat quickly and enough. Now though, the old dog (me) has learned a new trick. I can't wait to try it out on the Laser. 
We came 3rd in each race. A great result for me, not so good for Rosie.
Oh, and when I had a little go at the helm? A lovely craft. A rounded bottom, so no sensation of sitting flat on the lake. A light and effective rudder. A comfortable rear sheeted main and a fantastic crew! I want one!