Wednesday 20 February 2013

Building a Pulk Sled


     Winter camping takes quite a bit more gear than summer camping.  I don’t think ‘ultralight’ and ‘winter camping’ can exist together.  Especially when it’s -20C or lower, you want to be prepared and not kicking yourself for not briniging something that saved you a couple grams.  That said, carrying a lot of weight while trying o float on the snow with snowshoes or skis is counterproductive.  The best way to get around in the winter is with a sled, or Pulk sled as they are commonly called.  The advantages are it spreads the weight out so you can float on the snow more (and also less chance of breaking through thin ice), it can carry more bulk and more weight than carrying it on your back, and it also allows your clothes to breathe more, instead of having a backpack on your back, creating the perpetual sweaty back syndrome.  
 Usually it its attached to a hip belt by some means.  There some disadvantages though – the sleds are less maneuverable through dense brush and steep uphills are more difficult as you sometimes can’t get enough traction to pull the thing, but those are more rare situations and in general pulk sleds are great helps more than they are hinderances.
     If you Google ‘Pulk Sled’, you will find thousands of variants.  A handfull are commercially built, but usually home built devices of all sizes and shapes.  Some have covers, some don’t.  The majority has some kind of rigid structure between your hip belt and the sled.  This helps a lot in traversing slopes and also downhills – it prevents the sled from running into you.
After researching many of these I made a sled a while ago.  It costs less than $100 and it performs great. The sled I made from a Pelican Snow Glider I got from Canadian Tire.  It is very lightweight, but it is made of thin material.  Due to this, I didn’t want to pull the sled through the material itself, so I made a frame of PVC, attached to the sled with Nylon zip ties/cable ties – I drilled holes in the sled, tightened the zip ties from the bottom and cut off the excess.  I ran the rope through the tubes, so the rope pulls the frame, not the sled itself.  I made it out of CPVC water pipe, which does not get brittle even at cold temperatures.  Many plastics get brittle like glass at cold temps and will break or shatter.  The sled frame tube I used ½” tubing.  I cemented the tubes together with CPVC cement.
     For the front frame (between the hip belt and sled), I used ¾” tubing for more stiffness, and put two cross tubes in it, again for more lateral stiffness.  You want to size the length of this so your snowshoes or skis don’t hit it with normal movements.  Then I ran some 3/16” rope through the front frame tubes, all the way to the back of the sled and back the other side.  I happened to use polypropylene rope, but after comparing specs, perhaps nlyon rope is more appropriate as it is slightly stronger, but I am sure either will do. 
The rope itself acts as a hinge between the front and rear frames. At the front of the front frames, I attached mini caribiners with figure 8 knots, trying to get the rope was tight as possible so there is as little slack as possible between the frames.  The figure 8 knots simple rest inside the ¾” tubes in the front frame.  For storage or transport, the front frame folds backwards.
     Finally, my old LowePro backpack top transforms into a hip belt/fanny back with a robust buckle so I used that to attach the sled to.  It has a pocket I use or water and snacks.  I hand sewed a loop onto each side of the belt with high strength thread.
     I use leftover rope to lash gear to the sled, although bungy cords would likely be more convenient if I would find the right sized ones.
      I’ve used this sled for about 30kms so far of cold weather pulling on different terrain, some off track, and it works great.  It’s very controllable on downhills, and my gear is secured well in it.  My only negative views is that mine is this sled model is a little short for carrying lots of gear.  That, and the side and front lips on my sled are rather deep and can plow some snow and make it a little harder to pull in deep snow with first tracks.  One more thing, a cover would be nice to have to prevent snow from accumulating in the sled when trudging through the deep, perhaps I will design and make a cover for one for next trip.  Other than that, these are great for winter camping and a good project to make yourself!

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