Car roof rack tie-down straps, made of durable black polypropylene webbing. Car roof rack tie-down straps, made of durable black polypropylene webbing. Great straps that you’ll feel confident will hold your boat safely on your car or trailer. Hobie straps are padded to insure they do not scuff your kayak. The cam buckle is one of the easiest ways to strap your kayak on to your car. Keep an eye on these beauties ’cause your friends will want to ‘borrow’ them.