Saturday, 17 November 2012

MLD Duomid Buckle Failure

The Mountain Laurel Designs Duomid is a popular pyramid style shelter that has slowly eased its way into my kit selection over the last few months. Space is excellent, stability is good, and it’s very quick to pitch. None of that was the reason I’ve been using it so much though.  I chose the Duomid for both my Scottish Cycle Tour and Coast & Moor hike because it is the only shelter I own that has a front door! Doors can be useful if you are expecting to be using commercial campsites. Leaving an open shelter in such a busy public place is perhaps asking for trouble, if only from dogs! Privacy could also be a concern but wasn’t high up on my list. As it happens, I didn’t use any commercial campsites on either of those trips and the failure of the Duomid, on a particularly stormy night, has made me rethink that logic on shelter selection.

The weak spot of the Duomid design has always been the opening and its zip. The whole front of the Duomid can be opened up allowing for magnificent views and excellent ventilation. However, this front is also structurally important to the design of the shelter and its stability in a storm. The base of the Duomid is a rectangle with adjustable pegging points in each corner. To pitch, the base is pegged out, tensioned, pole inserted and adjusted, guys added and pegged, job done! The problem is to keep everything taut in a storm the base pegging points need to be tight which puts enormous pressure through the base seam of the shelter. The back and sides are ok with this as they are solid structures but the front is not. MLD have taken this into account with the design and added a buckle over the door zip which, when done up, effectively makes the front a solid structure and protects that vulnerable zip.  Further load is taken off the zip by a Velcro band (or press-studs) half-way up the shelter. In practice this system worked very well, until…

A common theme of my Coast & Moor hike was unseasonably bad weather. Heavy rain and strong winds were the norm instead of the warm, sunny and calm autumn days I had expected.  During one bad storm at around 01:00 the front of the Duomid exploded letting 50mph* gusting windblown rain rush into the shelter. The buckle had failed and the zip, unable to take the pressure, had ripped apart. Jumping out of my rapidly wetting down bag and into the night storm I tried to fix the problem by redoing the buckle, but it wouldn’t hold. As soon as I clicked it back together it came apart again. Thinking quickly, my solution was to remove the door guy line and bind the front buckle together using the cord. This worked well and lasted the remaining 3 weeks of the hike. Luckily, the zip appeared to have survived ok and I went back to bed and had a peaceful remainder to the night.

After investigating further I found that the prongs that should lock the buckle together had rounded and could no longer grip the buckle securely. The buckle is a fairly lightweight choice for such a vital job and given my experience could do to be a bit beefier. I shall replace mine with the same ones I use for hipbelts on my rucksacks. This will add a “massive” 1g to the total shelter weight and I doubt it will ever wear out!

So, how long did the Duomid last before failing? A pathetic 35 (mostly windy) nights! I think you will agree that is a poor performance from a shelter of such calibre, and from such an outstanding kit producer. I hope MLD will take the 1g hit and add a more substantial buckle on their Duomids (and Solomid?) in the future.

This experience reminded me why I like simple shelters without zips, buckles or Velcro parts to fail. MLD’s Trailstar or Cricket silnylon (not cuben) models can be pitched with the front almost to the ground and one or the other will be on my next trip to Tasmania.

* Although the forecast predicted 49mph gusts there was some natural shelter and the real windspeed was somewhat less. The Duomid is not the shelter to choose if you are expecting weather of that magnitude. A Trailstar is a better choice.