Jim, I found that after you have attached the two straps around the kayak and through the window/doors , then tie another line under the kayak and around the straps so that the boat can't shift side to side. I once had to tie down a Necky double onto a Honda CRX(without rack) for some folks that "had to get it right now", can be done but it sure looked comical, almost as good as the time a guy wanted a Necky Narpa, attaching a 17 ft. plastic kayak onto a cream colored Alfa Romeo Spyder took some creative efforts. All this without liability waivers. sigh, the good ole days.