look at the boat and find one of the eyes on the side of the hull that when you have a line from the shroud, it goes over the slot for the dagger board. Put a bit of bungee or shockcord from this eye and then tie it around the shroud plate. The shock cord needs to be tight to gold the plate, but not too tight so you cannot streach it to let the plate out. The shockcord just lies on top of the top of the plate keeping it down.