Peripheral note of caution-
Pay attention to the conditions of your straps. I was going cross country once and had stopped at a parking lot somewhere. Before getting back in my truck, I gave one of my cam-straps a bit of a tug to tighten up whatever tiny bit of slack had creeped in and it parted. I suspect there is a wide range of quality, but if the strap has faded (uv damage) or shows other signs of weathering, evaluate closely and seriously consider replacing.
Maybe I missed a lot here. Don’t most vehicles still have a structural member front and back for towing? My Hyundai has a really nice steel loop under the front and a spot in the rear bumper with a removeable cover for screwing in a towing
Not all cars have a spot for a screw in tow hook, plus having a strap run around a bumper cover to go underneath is less than Ideal to me. You have the pressure and rubbing on the paint, plus you have to crawl on the ground
I have had three cars now with the creeping-back headlights. Not a problem. Still can find a structural part of the cat forward enough to create apt tension.
I personally have never wanted to use the bumpers for the hood, seems less secure to me than running a rope or a strap around a piece of metal in the chassis.
As to the pop-outs, with the last three cars these have gradually disappeared. But then, most SUV’s that are so popular now also have plastic or rubber rather than painted metal down around the bumpers. So even if rubbing paint was a real risk (in my decade plus of using bow loops it has never been), there is not any paint to rub in most newer vehicles down there.
As does my Honda Fit, with a tow hook in the rear and a removable cover in the front to screw in a hook. I opt to use a quick loop under the hood rather than risk tripping over a tow hook extending past the bumper.
Straps or lines that run under the bumper can also get fouled by the car’s wheels if they get loose. If you’re unlucky and this happens at any speed it can cause catastrophic damage to the kayak.
See… Bent my boat in half
That’s true.
My friend ran over his bow line at 30- 40 mph. He had a new Eddyline Raven it turned it to junk instantly.
Bow and stern lines to secure boats on the roof.
Bow and stern lines for lining rapids.
Bow and stern lines for mooring to a dock.
The thread that won’t die?
FOB 
too.
With MiltonAvery on this one. Always use bow lines because they are early warning systems for anything else going on up there.
But also always secure to hood loops, whether you buy them or make them. So the lines cannot be long enough to catch in a wheel well or under a car.
No one is perfect, you can always screw up tying something off. But IMO if what you failed to secure is some place that you can’t see it is going under the car, that accident is entirely self inflicted.
Reason l do not use stern lines, safer to double strap than to have something l can’t see in back. If l were to do so, it would be tied off to hooks under the liftgate.
What does a stern line block sight wise?
I think you are confused. My point was that a stern line which is long enough to go into a wheel well has a LOWER END l can’t see.
Obviously neither could the driver l got away from on the Thruway whose stern line was bouncing freely on the pavement at 70 mph. His very nice expedition length sea kayak was one wrong bounce away from coming in half and landing in the windshield of a car behind him.
That’s why l said l would only use shorter lines to under my lift gate, should l choose, in back.
Those ratchet straps with open hooks on the end are a menace - I recommend avoiding them. The hooks easily get dislodged if things bounce around, and they will chip your window, paint, end up in a wheel well, etc. The ratchet mechanism is just begging to be overtightened to keep the hooks in place, which can easily damage the boat.
I’ve long recommended using a vice or other means to close those open hooks and then use a carabiner or other fastener to attach the bow and stern lines to your vehicle.
I’ve written Thule criticizing their use of open hooks. Interestingly, they seem to have manufactured their bow and stern tiedowns with both open hook and carabiner terminations. I don’t know if these are manufactured at different plants or if one is current and one is an older design.
I don’t feel the ratchet design increases the risk of overtightening. It’s not like a lever ratchet and proper tension is easily felt when using them. They just need to be snug.
Always use them, both. Tie the front lines to straps at each corner of the hood, they are bolted to frame under the hood. Tie one line in the back to the trailer hitch.
I would feel horrible if the boat came off the car and injured or killed someone behind me - a life changing event. the 5 minutes it takes to tie these ropes is nothing compared to a lifetime of regret and years of the certain lawsuits or criminal trials.
No one has ever given me 1 good reason NOT to use these safety lines. the only reason I can think of why people don’t use them is laziness.
If you have a good reason for NOT using them let’s hear it.
Just to keep this going a little longer… I have a question.
Should the bow line slant toward the front end of the vehicle (like this / ) or back toward the windshield (like this \ )? Or is either ok?
I have seen each of these ways recommended.