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I have carried a pair of kayaks on my car roofrack for many years with no trouble and always used bow and stern lines to the car towing points. As I understand it the bow and stern lines are primarily to prevent forward and backward shift of the boats, and secondarily to act as a safety in case of multiple strap failures or the roofrack detaching from the car.

My new car has towing points that a) are very inaccessible and b) the front ones are very far forward of the kayak bows. This means that if I take a bow line to them there will be nothing preventing forward movement of the kayaks (the rear tie points are almost underneath the kayak sterns and so are little help.

Therefore I have started taking the bow and stern lines to the car's roof rail, running them backward from the bow and forward from the stern.. It's more convenient, it provides better protection against backward and forward movement, and the roofrail is an integral part of the car so the kayaks will still be attached even if the J-racks fail.

Poor diagram follows. The red lines are the bow/stern lines to the rack mounts, blue lines to the towing points. Not to scale.

enter image description here

Is there any downside to this setup that I haven't thought of?

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  • If your diagram is to scale with the relative position of the boat and bars, bow and stern lines are not required. Though you might want to move the bars in a little as you're quite close to the ends of the boat. I've only seen a requirement for the additional lines on long boats loaded on short cars.
    – Separatrix
    Commented Sep 29, 2022 at 7:15
  • @Separatrix It's not to scale. The bars are not that close to the ends of the kayak. Commented Sep 29, 2022 at 15:38
  • As long as you can get 1/3 to 1/2 the length of the boat between the bars, you don't need bow and stern lines. Basically you need to ensure that the fattest part of the boat is between the bars and that you've strapped it down well and it'll be fine. If the boat is too long, it's normal to only have a maximum of 1.5 meters between the bars, then you'll need the extra lines.
    – Separatrix
    Commented Oct 3, 2022 at 7:51

2 Answers 2

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It depends how long your kayak is. The bow/stern lines to the bottom of a car are really only for long sea kayaks. I've never put lines like that on a whitewater kayak. For shorter whitewater kayaks it's two straps, one at each crossbar, that go through hardpoints on the boat.

Like this photo from a Palm article, except I'd usually also go through a hard point on the kayak: kayak on roof

For longer sea kayaks the bow/stern lines are not just for preventing front/back shifting. The stern line honestly doesn't do a whole lot. The bow line is largely to prevent the bow from lifting up and putting a bunch of force on the racks (since it's basically a large lever). I'm not sure your red line in the diagram will do as good of a job of preventing the bow from lifting. It's also a much larger angle so the force on the strap will be very high. And purely speculation, but the larger angle is probably not as good for your boat either. It's going to be putting stress at kind of a weird angle on your boat.

In short, I don't think there's ever a reason to use straps setup as the red in your diagram. Either have just two straps at the crossbars for shorter boats, or have traditional bow/stern lines like the blue in your diagram for larger boats. If your boat is short enough that the front tie in points are far away, maybe it just isn't necessary.

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  • The kayaks are 12ft and beginner flatwater kayaks. I don't tighten the bow/stern lines enough to put stress on the kayak, just taut enough to stop them shifting forward/backward. The J rack straps are pretty tight and the kayaks have never shifted sideways or vertically (unlike my previous setup without J racks which shifted whether or not I had bow/stern lines. Commented Sep 27, 2022 at 20:07
  • For a 12 ft flatwater kayak in a J rack as long as the two rack area straps are through hard points* on the kayak then I probably wouldn't bother with bow/stern lines unless I was doing a really long drive.
    – noah
    Commented Sep 28, 2022 at 16:23
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Your understanding is incorrect. Bow and stern lines do very little to constrain fore-and-aft motion, generally being orthogonal to such motion. That's the function of the main straps, being positioned either side of the widest part of the kayak.

The bow and stern lines are to prevent the kayak pitching up or down as they are buffeted by headwinds. Just a small amount of pitching can quickly get out of control, as it then presents a greater surface area to pitch it further. If the vessel is long compared to the separation of the bars, it can stress the system to the extent that you lose the boats off your vehicle, and that's quite inconvenient - especially if other road users are around at the time.

Your proposed (red) system has no effect on pitching, as it's just linking to the existing anchor points.

I recommend using a line if the bow extends ahead of the front bar by more than the inter-bar distance. Although down-pitching tends to be less of a problem, the stern line helps keep the bow line tensioned, rather than flapping about.

You don't necessarily have to attach to your vehicle's towing eye(s). On my car, I've found existing holes to which I have bolted short tape loops, which tuck away when not in use, but can easily be brought out for my tie-downs to clip into.

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