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Has anyone experience with attaching a hammock to roof rails of a regular car?

I just bought a hammock for my next camping trip. I will be traveling mostly by car and sleep in a tent but wanted something to relax in outside of the tent or car and also might try sleeping in the hammock. My question is: Is it possible (i.e. safe for both, me and the car) to attach one side of the hammock to the roof rails of the car? This might make a lot of places hammock-feasible, as I‘d only need one additional tree.

I am pretty sure that I have already seen auch a set-up with a Jeep-like car somewhere. But the car in question is an Opel Astra with normal roof rails so I fear that the rails might not withstand the sideward pull a hammock would cause on them. Since it is a borrowed car from a family member, I really do not want to damage it.

Any advice?

Charlie Brumbaugh
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Jon Isr
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    If you do it: ideally you want the hammock to be "behind" the car, parallel to the usual driving direction, and not - as would be intuitive - to the side of the car. This is because that's the load the roof rails are more designed to do – Hobbamok Jun 14 '19 at 10:24
  • @Hobbamok Thank you! That’s a good point. – Jon Isr Jun 14 '19 at 11:56
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    @Hobbamok you could even tie off to both rails that way – Chris H Jun 14 '19 at 14:29
  • Funny how no one mentions that the weight of the occupant might factor into the equation. – Ron Day Jun 14 '19 at 10:50
  • It might help if you could qualify this somehow. How much weight can the hammock take given the weight and design of the car? What other factors play a role? The type of ground the car is situated on? Assuming the hammock and other side are sufficiently strong, obviously. – JJJ Jun 14 '19 at 12:52

3 Answers3

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The load limit for directly mounted roof bars is around 60kg - 70kg for ordinary (European) cars. Usually the load limit for rail mounted bars is lower, but that's for vertical and dynamic load. This is a static load so you're probably ok.

Basically if it was my own car and not in great condition I'd do it, attaching the hammock to the far rail and hanging over the near one. With a borrowed car I wouldn't.

On the other hand if you get a single support for your hammock such as crossed poles, and using a tree at the other end, you can certainly use the tow loop as an anchor as that's more than strong enough to take the load.

Single tree hammock

Separatrix
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    Estate cars can have a higher limit - 100kg on my old Peugeot with permanent bars supported in 3 places. It's probably best to tie the hammock at the middle support for side loading. And they're quite overbuilt for supporting that sort of load statically. – Chris H Jun 13 '19 at 11:48
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    @ChrisH, as you say, dynamic and static loading matters. – Separatrix Jun 13 '19 at 12:58
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    Orientation matters - if you can arrange the direction of pull to be more in line with the car's axis, you're at much less risk than when loading at 90° (full abeam) to the vehicle. Check that you're not fouling the boot opening, though, or you'll curse yourself every time you need to get something out! – Toby Speight Jun 13 '19 at 13:25
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    Also, check that you take the hammock down before trying to dive to the grocery store the next day, or else you'll hear a distinct eee...eeeeeee.... BOOOOM! as the line snaps. Ask me how I know. – dwizum Jun 13 '19 at 20:14
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    Thanks a lot! The idea of using the tow loop as an anchor sounds really promising. I hadn’t thought about that. – Jon Isr Jun 14 '19 at 11:55
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    @dwizum Obligatory question: Was the hammock occupied? – gerrit Jun 14 '19 at 13:23
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    Seems to me that a person in a hammock would be a dynamic load, not a static one - the car isn't moving, but the load is. With the ropes at a typical 30 degree angle, the tension on the rope will equivalent to the person's full weight (double it for the angle, halve it because there's two ropes), so many adults are going to exceed that 60-70kg design limit for the roof rails. Only half that tension is vertical weight on the rails, you'll have 86% of your body weight pulling the rails laterally, which I'm not sure rails are designed for. – Nuclear Hoagie Jun 14 '19 at 13:24
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    @NuclearWang, by dynamic we're considering the fact that the system should be able to handle 1g braking/cornering and other similar forces, you should be ok as long as you're not treating the hammock as a trampoline. – Separatrix Jun 14 '19 at 13:38
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I would attach rope to both rails and perhaps even the door pillar on the opposite side. This would help spread the load if you’re worried about weakening the rail.

Update: In fact why not just tie across the roof to the opposite door pillar and simplify the task. One knot.

Stefan
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I have done this on my 3 series wagon. I had the strap tied around the middle vertical support of one of the side rails. I also have cross bars installed, so I don't know if that helps in anyway to reenforce or distribute some of the load to the other rail, but I didn't have any issues. I just made sure that the strap was situated in a way where it came over the top of the bar so that it wouldn't rub on the paint of the roof.

Mike B
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