Over the winter, I made a spinnaker launch bag for my U20. Mine is a semi-slider. I have loops on each of the 4 top corners. The back two are clipped to a line that runs to eye straps on the bottom side of the jib tracks. The back clips also have shock cord that are clipped to stretch out the back...easily un-clipped. The front two loops are attached to line that have a clip attached to eye straps on the bottom side of cam cleats...easily un-clipped. I can un-clip one side of the front and then un-clip the back shock cord, at which point the back can slide to the other side and the free front clip can be clipped to the back line...opening up the companion way. Each side on the top, I sewed a tube. On the right and left side, I inserted a p-tex pipe...light weight, semi flexible; you could use a batten as an alternative. Works great!