 | Home > Expedition & Overland > Roof tent question |
 
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| dantastic Member Since: 04 May 2010 Location: London Posts: 367  
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There are different kinds of roof tents but they all have one thing in common - dry as a bone inside. Even if you pack them up wet.
* I'm sure you can get Chinese crap that will take in water but the branded stuff sold here is all good. |
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9th Feb 2018 3:31pm |
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| JMG Member Since: 16 Apr 2014 Location: Surrey Posts: 222 
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I have a magical on top of mine, great bit of kit, always dry.
Good luck you will enjoy every camp out.  Click image to enlarge |
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9th Feb 2018 5:46pm |
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| Badger110 Member Since: 06 Feb 2018 Location: South hams Posts: 1025 
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Are you saying if i pack up a wet tent in the morning, when i come to unpack in the evening, the moisture wouldn't have soaked through the material? I can't see how that is possible without using a plastic based material ( think Visqueen or similar ) which is a complete barrier for moisture ( hence used for damp proofing ) which isn't going to work on a tent! Tuff trek state their material is water resistant, not water proof, which is correct as i've never heard of a tent/jacket/boot ( except wellies! )/sock/clothing material being water proof as the nature of the material won't allow it to be completely waterproof. I'd expect a wet tent being packed away to be pretty damp all the way through by the time you come to open it up later on, perhaps i'm missing something? |
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9th Feb 2018 7:02pm |
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| Badger110 Member Since: 06 Feb 2018 Location: South hams Posts: 1025
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i've been looking at these but i'd want a rear awning set up as well, and i can't find a set up with these and an awning  |
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9th Feb 2018 7:03pm |
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| wyvern Member Since: 14 Dec 2009 Location: Cornwall Posts: 2068 
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^^ you can with a 270’ awning and wall/room set up .....
http://tuff-trek.com/awning-systems.html just a thought ! Poppy - TDCI (Puma) 110XS 2.2 - Camper conversion - see the build here - https://www.defender2.net/forum/topic56530.html Elgar -TDCI(Puma) 110XS Dormobile - now sold Devon & Cornwall 4x4 Response - DC126 |
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9th Feb 2018 7:22pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7682 
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I have a Maggi and a foxwing awning.
Maggi has gone away wet on outside, goes back up wet on outside and then dries out. Inside has always been dry inside even being single skinned. Cheers James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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9th Feb 2018 7:33pm |
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| UtilityTruck Member Since: 09 Jan 2014 Location: Oxford Posts: 463
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I think the answer is that roof tents can be made of much thicker material due to being vehicle mounted vs a ground tent that must remain portable. Therefore it takes a lot more head of water to soak through to the inside. 2014 Keswick Utility 2.2
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9th Feb 2018 8:25pm |
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| williamthedog Member Since: 29 Dec 2012 Location: south wales Posts: 3441 
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Maggiolina and foxwing for me too
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9th Feb 2018 9:03pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578
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There has be major advances in textile technology over the last few decades.
Fabric for tents/outdoor clothing have to be both waterproof and breathable. Waterproofness is measured via hydrostatic head which is the height of a column of water above a piece of fabric before water passes through. Breathability is measured by the amount of water vapour passing through a metre square of fabric/day Visqueen would have an extremely high hydrostatic head and basically zero breathability Many years ago anoraks were made from PU nylon very waterproof very uncomfortable as sweat condensated on the inside as breathability was low. The science behind a waterproof but breathable fabric is quite straightforward. Holes in the fabric are too small for a water molecule to pass through unless under high pressure. However the holes are large enough for a water vapour molecule to pass through. So when a tent is made of a waterproof but breathable fabric is packed away wet there is not enough pressure to force the water molecule through the fabric. However if packed away wet for a long time you might get musty smells/waterproof so it is good practise to dry it out as soon as practical. Rooftents and awnings. If hard shell roof tent they can be accessed from either the rear or the side. If a 270 degree awning then roof tent accessible from the side. Side awning with hard shell then either rear or side entrance is OK Soft shell folding tent you can have them opening front/rear or sides so will work with either side awnings or 270 degree awnings. 4x4overlander stocks the German made Nakatanenga Roof Lodge tents, the Italian made Authome tents and a range of awnings at here Brendan |
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9th Feb 2018 9:49pm |
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| Badger110 Member Since: 06 Feb 2018 Location: South hams Posts: 1025
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Thank you for the reply brendon, we are looking at an Autohome Overland tent at the moment.
I understand the technology behind the material used and in theory it works very well, however i've found in the past that waterproof/water resistant materials in jackets works well until you compress the water onto the material, ie at the straps of your rucksack on the shoulders and around the armpits ( yes the wind and rain have a horizontal effect on Dartmoor causing rain to get everywhere! ). I wouldn't want to fold up a wet roof tent and find that later on the contents and inner area are wet due to the damp material being compressed and allowing moisture to travel through it. Perhaps i'm over thinking it, it's good to get feedback on the subject, so thank you all  |
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9th Feb 2018 11:31pm |
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| Pat Member Since: 05 Dec 2016 Location: Somewhere new! Posts: 363 
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"The science behind a waterproof but breathable fabric is quite straightforward." .......
Surely, size wise, a water molecule liquid state is the same as a water molecule vapour state!? It started with a kiss, never thought it would come to this. SIII CSW Safari, limestone, (JAC 914N). Where is she now? It's not a car, it's a way of life! |
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9th Feb 2018 11:43pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578
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Hi Pat, the answer is both NO and YES. That is rather a simplified version of how waterproof/breathable fabric works. I used to work at Leeds Uni Physics Dept and had friends who worked in the Textile Dept working on things like the waterproofness and breathability of fabrics.
Now for instance if you have a breathable fabric with holes large enough for water vapour molecules to pass through as it becomes wet from rain the hole size might decrease as the fibres get wet and swell decreasing the hole size. Now in clothing to prevent the uncomfortableness of sweat condensing on the inside of a waterproof/breathable fabric there may be a inner layer such as a netting or pile fibre fabric to reduce the discomfort. Now on a tent you may use a flysheet to keep the inner tent fabric dry so it is still breathable. Now if the relative humidity on one side of the fabric is 100% it is extremely difficult for water vapour to pass through the fabric on a lower relative humadity side. to higher humidity side. There are many scientific papers explaining how waterproof/breathable fabrics work. It is rather difficult to condense many pages of scientific research about bond angles/bond length of water etc into a couple of sentences so it can be readily understood. Call it a bit of hand waving/glossing over facts rather then a attempt to misguide people. If you want to look it up in more detail look for Uni of Leeds Textile Dept with Dr J Keighley, Dr M Taylor and Dr D Brooks for more detailed information. HTH Brendan PS Now having a quick look at the size of a water molecule the liquid state of water appears to have a longer O-H bond length and larger angle then a gaseous water molecule. Add to that a liquid water droplet is more likely to have a larger number of water molecules then water vapour. Must admit I am getting a bit out of my comfort zone talking about size of water droplets. So over to someone with a greater depth of knowledge |
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10th Feb 2018 1:15am |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578
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Hi Badger, yes rucksacks etc will compress fabric etc. Now in the rain are you experincing rain coming in under rucksack straps etc or is it a case of condensation from the inside?
Now think, hot day, non waterproof high breathable tee shirt with a heavy rucksack on a sweaty uphill climb. Back of tee shirt will be wet from condensation not being able to effectively breathe through back of tee shirt due to compression from rucksack. Sides dry, top of chest area wet. Well that is my experience. OK all depends on position and density of sweat glades on different people etc etc. Will admit this is a brief gloss over, hand waving explanation. A roof tent fabric will be more waterproof then your cotton tee shirt. Personally I think you are overthinking the issue. Not necessarily a bad thing as hopefully you will be able to make an informed decision. When we sell roof tents/oztents we know they are not cheap purchases and we often send people away to consider things carefully and make an informed decision rather then a impulse decision because a salesman is breathing down their neck/twisting their arm. Brendan |
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10th Feb 2018 1:49am |
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| Hendrix Member Since: 04 Oct 2016 Location: North Notts Posts: 103  
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We had a conventional style roof tent (Howling Moon) on our first set up. These tend to be made from heavy canvas with light flysheet. Went to France for our first test trip and it rained a lot and we moved plenty. After a couple of days with the canvas never really drying off the duvet did feel slightly damp on top but nothing serious. These types do work better in this regard in the countries they come from as they dry quickly with a bit of warm weather. In Ethiopia we would get major downpours most mornings but 30 minutes after it stopped everything was dry.
Looked at the Maggi type tents for our second setup (quicker/easier to setup) and whilst the performance of the actual tents looked good it was the getting in and out that decided us against. In the folding canvas style tents you have a sheltered entrance. In rainy conditions you can open the tent flap without any rain getting inside and have space to remove any waterproofs and hang them outside instead of taking the wet things in. |
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10th Feb 2018 2:31pm |
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