In that case, I usually get the jib CRANKED on hard and as much daggerboard as you feel safe with. The boat should be easy to control that way and I usually find that I need to travel in to the hiking strap and put a little sheet on to balance the boat. Daggerboard may be your problem - make sure to get enough in the water to get a bite. I drop the rudders off their upper lock (Nacra style) and let them float in the water behind the boat. I'm also careful to watch the water flow and if a sizeable wave gets the boat and starts to back it down, I pull hard on the cross bar to try and keep the rudders at the top of the water and from being dragged down where they might catch the sand and get damaged. I've (knock on wood) never broken a rudder or casting due to a beach launch.