Be sure to read it if you haven't yet. I haven't lost a canoe in over 40 years of cartopping one around, a lot of that being on Interstate Highways. Like Joe, I mourn the disappearance of roof gutters from cars beginning around 1990 or so. That forced me to replace a perfectly serviceable set of cartop racks because I no longer had the gutters to anchor then down.

Like Joe, I went to a Yakima system. Though they do not give these away by any means, they are worth the $$ to get the security they provide.

I will also second Joe on the cam locking straps available under several labels, Yakima, REI, Thule...And I thank Joe for the tip on twisting the strap.

The only thing I can add is this. Though I admit that, for short runs out to a local lake, I only use the straps, on longer trips I do not want to risk everything on one tie down system. That is where a system I call the Chicagoland Canoe Base system comes into play. CCB is where I first saw it anyway. BTW Ralph Freis the owner of CCB would say that this tie down is all you need. To be on the safe side, however, I use both a belt and suspenders.

For each canoe you will need 50' of rope and two large "S" hooks. You are probably bringing 50' of rope along anyway. You also have to learn to tie a taught line hitch. Once you get the hang of the hitch, there are no other knots.

Now I have to promise some pictures to show you how to tie it down.