The Wast Water fells 3-day backpack was the first field trial of the mesh panels modification that I had made to my Hilleberg Akto by Scottish Mountain Gear.
These mesh panels replaced the solid nylon vertical walls at either end of the inner and were designed to solve the bad ventilation problems I experienced on my first two solo trips.
On this trip the conditions were not cold enough to give a really good condensation test but the initial results are very encouraging.
This picture is from the first pitch on Yewbarrow, the mesh panel can be seen at the far end.
I’m happy to report that they worked very well, as expected really since the idea came from our Voyager inner which has never given us any such problems. For the test I kept the standard outer flysheet vents unzipped as usual and the inner door closed. I also closed off the standard triangular mesh panel in the door: the physics involved is not obvious (to me), having a side panel open as well could improve the ventilation due to a greater area of mesh, or worsen it by interfering with the end-to-end flow.
First pitch on Yewbarrow
Conditions:- very little wind, mild evening and night well above freezing.
After an hour or two the improvement was readily apparent even without a significant breeze: no feeling of stuffiness and the exchange of air was clearly working sufficiently. In the morning the inside of the inner was completely dry. Curiously the underside of the flysheet was only slightly moist compared to the sopping wetness on the Cross Fell trip, but that must be a coincidence I would think - maybe it was a pretty dry airstream today and it was milder than the previous trip. I can’t see how a better ventilated inner could help with condensation under the flysheet, but what do I know…
Second pitch at Lingmell Col
Conditions:- a good breeze blowing, misty and drizzling much of the evening with a brief spell of proper rain, none overnight. Similar temperature to the previous night.
No surprise with the ventilation here: it was of course even more efficient with the help of a good breeze, but as we learned from the Voyager, the mesh cuts down the perceived flow very effectively and it didn’t feel at all draughty. I concentrated on the windward end of the tent to see if any drizzle and rain could penetrate the mesh via the open vents, but there were no problems. The overhanging ends of the Akto flysheet shield the vents and inner well in most conditions, but in the event of a strong wind driving the rain at a shallow angle, the outer vent on the windward side could be zipped part way up to stop any ingress. In fact this is what I did just in case the weather worsened overnight.
In the morning the inside of the inner was again dry, a very pleasing result with the increased moisture in the air. Very curiously, the underside of the flysheet was again only slightly moist which was really surprising, though I still suspect that it’s nothing to do with the new mesh panels.
Verdict: I’m really pleased with this modification so far, the inner ventilation is vastly better. There was no trace of moisture in the inner on either morning of this trip, but I’ll have to wait for a colder night for a more demanding test.
9 Comments
I’m impressed with your modifications Geoff. I’ve had condensation dripping from the inner in the morning some times. Looking forward to your cold weather test. I may have the same done to my akto. Have you considered talking to Hilleberg about this? Perhaps they’d put mesh panels in themselves.
This mod is generating some interest, it appears that a lot of people have experienced troublesome condensation in the inner. The panels must improve things a great deal in cold weather.
I think I will email Hilleberg to let them know about it, once I’ve had a colder test pitch and collected these blog entries into a review on the main website. The Akto has been around for years and is well established, I don’t know how they’ll take to me telling them the basic points of tent design!.
I’m not so sure this modification is a good idea, because it interfers with one of the designs features of Hilleberg Tents.
Contrary to Terra nova, Helsport and others, Hilleberg uses a breathing inner tent. To keep the inner free from condensation it relies upon a temperature gradient with the space between fly and inner. If you keep the inner warmer it will definitly stay dry, exces humidity will leave the inner by evaporation. Venting the inner will only work if the air you use to vent with has a lower humidity as the air in the inner. On cool misty British mornings, especially in still air, this will be rarely the case. Furthermore venting with cool humid air will decrease the temperature gradient and hence increase condensation. Of cause camping in such conditions is always prone to condensation, but venting will increase your problem in this case. The best practice with all Hilleberg tents in these circumstances is to close up the inner tent and let the inner warm up. Only vent the fly minimal. On the Akto it means closing the outer vents and closing the inner tent door vent.
I had to learn this , like many others the hard way. If you’re used to tents wich rely on venting to keep the inner free of condensation you are quite likely want to over ventilate a Hilleberg. But trust me keep it warm, and it will keep you dry, whatever the weather.
As for basics of tent design. I think Hilleberg is well aware of the basics. On the Scandinavian market there is fierce competion between Norwegian Helsport and Swedish Hilleberg.
Helsport leads the race for inner tent ventilation. Check there AirflowII designs . And Hilleberg leads the race in breathing inner tent designs
That’s very interesting Rolf, thank you for presenting the technical argument from the designer side. I’ve never heard of this concept as applied to tents, it sounds similar to the process used by membranes like Goretex in clothing.
I’m sure I will never regret having the mesh panels, if only for the ventilation itself, regardless of the condensation issue: I really want a steady flow to provide fresh air whatever else happens. This is what prompted me to have the mod done, I wasn’t thinking about condensation at first.
I know there will be many other Hilleberg owners in the UK who will be interested in this information, some of whom have experienced serious condensation issues.
Very interested to read your results so far, Geoff.
I have to say I’m a little surprised by Rolf’s suggestion. I understood that the commonly held view was that you should vent the outer as much as possible, that the end zips should always been open, and at least the top of the outer door. I’ve done this with my Akto, and still had condensation! This is why I’ve almost given up on it.
If I’ve understood Rolf correctly, you should keep the end vents closed, let the tent warm up, and rely on the inner to vent itself? Seems to go against the advice I’ve seen elsewhere, I must say.
Perhaps Rolf is correct. I’ve got the Hilleberg catalogue open, and for the first time I’ve noticed it says the head and foot ends of the inner are made of venting fabric.
Certainly got me thinking! Thanks.
Richard
The main problem I’ve had with condensation is that it tends to drip from the ridgeline on the inside of the outer onto the inner tent.
My solution was to tie a piece of string to the inside of the outer tent at its maximum hight and thread it through some of the loops so as it re-directs water away from the inner tent.
It’s not a perfect solution but it does minimise drips.
Hi Geof,
Second attemp, I understand my first reply must have gone missing in your mail.
I’m sure you will not regret the meshpanels. But you might want to find a way
to regulate airflow. Have a close look at how Helsports Airflow II works.
(http://www.helsport.no) look for page “About the tents”. Then have a look how they
incorparted this in their Ringsted model (see under tents/pro /ringsted)
All you have to do in your Akto is this:
- close the outer vent away from the wind. (best would be if you also could close
or block your innertent meshpanel away from the wind.)
- modify the closing flap of the innertent door in such a way you can open and close this
panel from above. Hereby creating a ventilation opening directly opposit the ventilation
opening on the top of the flysheet door
You now can use the innertentdoor flap as a airflow valve. (funktion C in airflow II design)
By adjusting the size of the opening, or closing it you regulate the airflow through
the innertent. In winter you can then opt for preserving warmth (and evaporate humidity
Hilleberg style) and in dry or warm air situation you can opt for ventilation
in Helsport style. Or any graduation in between as you like.
Regards
Rolf
Great site!
Nice to see a proper MOD! The akto works well in all conditions and opening the flaps at either end in all but the worst conditions has reduced condensation to normal levels. Remember it is a small tent so condensation will be greater than in a similar but larger tent. I compared condensation to another small one man tent in very very damp conditions and the amount of condensation was similar in both tents.
I have a full mesh inner for my Akto and it is great in the summer months. It feels ‘light and airy’ rather than closed in and warm/ muggy. It is not really suitable for winter camping though.
The standard Akto performs as well in the condensation issue as other similar tents I have seen in it’s standard form.
Sometimes ive had condensation sometimes ive had hardly any, i think choosing a spot where theres a breeze blowing through the tent can help as can pitching in a place where when the sun comes up (if there is any can help) at the end of the day a few drops of water isnt really a big deal just part of camping as long as you can seek comfort that the tent will take horrible weather and keep you dry.