Thanks Jake. Yes, on my "beach test" the jib was where you mention with respect to the spreader , I used similar criteria on my old cat. As you say I need more tension but I couldn't, the clew pulley touched the jib block. It seems I'm not on the wrong path, I will have to find a more rigid line and maybe cut some length to my jib block, for example removing the fast shackle that I added. (I did like it though...). I will also verify that both sails twist off similarly, I didn't think of that.