Pitching a Tent in the Snow

Roger,

Thanks again for another great article. It seems timely to revive it again for the winter. I really appreciate your attention to detail in describing processes – the details are what keep me coming back to BPL.

I have a question regarding your comment on tent pole lengths – "shorter the better."

What has been your experience with the difference in stability between 2P, 3P, and 4P versions of 3 pole tunnel-tents (for example the Hilleberg Nallo 2 GT vs 3 GT vs 4 GT). I recently inherited a Helsport Rondane 4 and am wondering if the loss in stability/strength in the 4-man version will be appreciable – i.e. would two 2 person tunnels be a vastly superior option for 4 people due to the strength/stability advantages of the shorter pole lengths of the smaller tents?

Hope you are enjoying the holidays.

Cheers,
Brendan

Hi Brendan

First of all, I had better point out that I have not tested the Nallo tents (yet). However, I have tested short and long poles in other tents (tunnel and done and pop-up). There are two main points to look at here.

Using the Nallo as an example, you can see that going from a 2-man tent to a 4-man tunnel tent changes the biggest pole length from 305 cm to 368 cm: a 20% increase in length, and they are 9 mm poles. The biggest pole on the Helsport Rondane Light 3-man is 295 cm long. I couldn't find a Rondane 4.

Compare that with the 1-man Soulo (344 cm 9 mm) or 2-man Staika (387 cm 10 mm). Other small pop-ups and domes inevitably have similar long pole lengths as they have to span the length of a body.

So it would seem that tunnel tents always have shorter poles when you match tent sizes. That makes the poles very much stronger – the flex is a polynomial function of length. Translation: a small increase in pole length gives a much bigger decrease in strength.

The second factor worth looking at is how you pitch the tent relative to the wind. Pop-ups in particular do not have a 'good' direction, but tunnels do. Increasing the size of a tent is always going to reduce its strength, but the tunnel design does make about maximum use of the strength of the poles when the wind is end-on to the tent. Side-on – the poles on a tunnel are still shorter than the poles on other designs.

So the bottom line for me would be that the Rondane 4 is probably still pretty good as a mountain tent, although the fabric span between poles is a bit long. My suggestion is to try it out, with a couple of friends, and see how it goes. I suggest it would be a bit TOO big as a solo tent! Photos would be interesting.

Cheers

Thanks for your quick reply Roger,

I had the chance to read through your designs and thoughts on your MYOG tent website last night – (http://www.bushwalking.org.au/FAQ/DIY_RNCWinter.ht Definitely recommended for anyone that is interested in the finer points of mountain tent design). Thanks for posting that, it was a great read. Its quite an accomplishment to create something as smooth and efficient as your 4 pole 2-man design. I wish there was something commercially available that used a similar design and incorporated your CF poles (for those of us that are still refining the finer points of sewing summer bug inner tents : ) ).

Below is a link to the last available Helsport Rondane 4 that I could find online – I believe that sometime after 2005 (mine is a 2005 model) Helsport changed styles and stopped producing the Rondane 4. The website has the basic floorplan/fly diagrams as well as the picture that is embedded below.

http://www.reittipiste.fi/product_info.php?manufacturers_id=70&products_id=692&language=en

Additional information on the original Rondane line-up:

Rondane 3 Packed weight w/o stakes: 2.2kg, 1 pole x 295cm, 2 poles x 220 cm
Rondane 4 Packed weight + guylines w/o stakes : 2.79kg (measured for mine with heavy stock guylines), 1 pole x 347 cm, 2 poles x 270 cm

Fly material (both): Superlight 1000 Ripstop Nylon
Pole material: Scandium Superpoles (34cm sections)

Its a bit hard to see in the picture but the fly has quite a large vent on the side opposite the door that is supported by stiff foam and is approx. a half circle of 30cm diameter.

I hope all's well down your way and you aren't getting hit by the brunt of the storms down there (my family out in Queensland have sent some amazing pictures of the flooding/highway waterfalls).

Cheers mate,
Brendan

Good article Roger, very authoritative and well illustrated.

I like the shot of an Atko under a snow load with a bent arch pole.

My winterized 4 season TT Scarp 2 has a heavy duty main arch pole for winter (thicker tube walls and larger diameter). That plus the internal X-ing poles mod and good guying make it very storm worthy.

The same mods apply for my TT Moment DW with the ripstop inner tent. (See the Tarptent Thread, first post photos.)