I have an 18 ft. fiberglass sea-kayak, which I mount to the roof-rack of my junky old station wagon with Yakima "Sweetroll" saddles - ratchet straps around the saddles and bow and stern to the bumpers. Unfortunately, while on a recent trip I suddenly noticed a 3-inch crack materialize in my windshield, which rapidly grew to an 18-inch crack.

I didn't see any impact that started the fracture and no part of the mount or the straps actually rests on the windshield - so I'm concerned it was the tension of the bow and stern guy-lines flexing the roof and putting too much pressure on the glass. The windshield is fixed, but I'm a little gun-shy about putting it up there again. Is there a better way to distribute the pressure on the roof? Should I just not ratchet the bow guy line down as hard? (I generally ratchet it down pretty tight to keep the strap from vibrating madly)

  • 1
    My first though is the force generated by a Bow strop should be nothing like the forces generated driving down the road. How tight are you doing the bow line? Anything tighter than you get from a simple cam lock and a small amount of effort is too tight.
    – user5330
    Mar 1, 2015 at 6:47
  • We usually have two kayaks on our car but we use a pair of J bars to hold them each in place, and only use a bungee cord down to the tow loop to keep the fronts in place, otherwise we strap them to the roof rack / each other to keep them tight, not using ratchet straps either. Do you tie down straight onto your roof rack?
    – Aravona
    Mar 2, 2015 at 8:01

3 Answers 3


The problem probably won't happen again, assuming you tighten down the kayak with reasonable force.

The glass in most cars is (was originally) installed with some flexible material around the edges (rubber or urethane sealant in my experience). That stuff probably hardened on your junky old station wagon, allowing more stress to get to the glass. Also, many years of heat cycles doesn't make glass any stronger. Then when you put the kayak up there, it was the straw that broke the camels back.

Hopefully your new windshield was installed with new rubber/sealant/whatever, and is now isolated from the flexing of the roof.

Also, try putting a knot or twist in the straps instead of tightening the !@#$! out of them. It'll look sloppy, but vibrate much less than a perfectly flat strap.


I've hauled pretty much everything you can imagine on the tops of my vehicles through hurricane force winds. Southern Alberta is one of two places on Earth where Chinook winds regularly occur. Winds in excess of 100km/h are a common thing here, I used to fight constantly with my 17' Canoe before I finally installed a roof rack. I used to use foam canoe blocks and 4 ratcheting cargo straps to clamp the bow and stern down so hard onto the top of my truck that the roof would collapse, the hull would flex, and it still wouldn't be enough to keep it down, but I've never cracked a windshield before.

I actually happen to be an independant Yakima rack dealer now. While I very much doubt that the cause of your crack was the rack system, I can't speak for the integrity of your station wagon.

The bow and stern lines aren't meant to be cranked down either way, just firmly and evenly snug so that they can help reduce whatever wiggle your kayak may have. What @Pepi says is right about putting a few twists in your strap to reduce vibration, you'll notice every trucker you see on the highway does the same thing.

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I wouldn't worry too much about your windshield, there's no way that you should be able to generate enough force to flex the steel frame of your vehicle using your kayak and a boat strap.


I see lots of people using bow and stern lines but really they are not required.

I have travelled 600kms in a single journey with my 18ft sea kayak on the roof using only two centre straps. Bow and stern lines have more chance of causing your kayak serious damage imho.

  • 3
    You've never driven through a Chinook... Try cruising in a crosswind with 120km gusts then tell me bow and stern lines aren't required.
    – ShemSeger
    Feb 28, 2015 at 2:59
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    Without the Bow and stern line the roof rack can separate from the car. You would be surprised how often this has happened. The Bow line usually stops this happening and if it does, keeps the Kayak attached to the car rather than doing a reasonably accurate reenactment of the first Adrian V rocket.
    – user5330
    Mar 1, 2015 at 6:42
  • @ShemSeger That's hyperbole, how often will anyone encounter 120km crosswinds? In any case 2 straps will not break under this force, though your car may be blown off the road.
    – alanh
    Mar 2, 2015 at 18:14
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    @ShemSeger Ok, if you live in Southern Alberta it may be a good idea to use stern and bow lines :)
    – alanh
    Mar 2, 2015 at 18:30
  • 3
    This answer contradicts a vast majority of advise on securing Kayaks to rood racks. By far a majority of kayak manufacturers recommend bow and stern lines. Most rack manufacturers not only recommend them, the warranty is not valid if these are not used. Every magazine article I have read on tieing down yaks recommends bow lines. Up to you to make you own decision, but readers should not be mislead by answers into doing something the industry considers unsafe.
    – user5330
    Mar 2, 2015 at 20:38

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