You have to read all of the instructions Posted by: wskayak on Jun-21-12 1:13 PM (EST)
Your supposed to tie and the front and back of your boat down to the bumpers. So if the cross-member J hook wasn't installed properly or has become loose or rusted, you wont have a calamity on your way to the launch. So its ok to tie the straps just to J mounts-- in fact there are guides to hold the straps.