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124 lines
6.1 KiB
HTML
124 lines
6.1 KiB
HTML
<!DOCTYPE html>
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<html>
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<meta http-equiv="Content-Type" content="text/html; charset=utf8" />
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<title>Stone bridge bivvy rigging guide</title>
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<link rel="stylesheet" type="text/css" href=/css/main2.css />
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</head>
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<body>
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<h1>Bivvy Rigging Guide</h1>
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<p>Every year some poor bugger who has probably never done it before it
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gets to rig the tarps and be responsible for any soggy miserable
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nights that might result if it's not done well enough. Starting from
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the bare space it's really quite hard to know where to start if you've
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not done it before, so this doc attempts to provide some advice.</p>
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<p>Until 2014 we had a shortish green tarp (10mx6m) wrapped up the back edge at upper entrance and a separate tarp for that upper area. It wasn't very good. In 2015 we bought a much longer big white tarp (15x6m) which covered the whole rear area down to the ground. In 2024 we bought a replacement but due to a documentation error that one is 15x10m which is really too wide. This description has been updated for the 2024-on version.</p>
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<p>There are two essentially-separate jobs:
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<ol>
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<li>the
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<a href="water">water-collecting tarps</a>, and </li>
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<li>the <a href="#main">main tarp</a></li>
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</ol></p>
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<p>If there is any chance of it raining soon, <strong>start with the <a href="water">water
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tarp</a></strong>, as you <strong>really</strong> don't want to miss collecting all that water, and
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setting it up in the rain is rubbish.</p>
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<h2>Terminology</h2>
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<p>I will describe things as if standing at the bottom entrance looking
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up, because that works for both sections. So the
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<strong>left</strong> wall is the
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gear/stove/animal-hole wall. The 'back' is the top end of the bridge.
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The 'front' is the main entrance.</p>
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<p>Tie bungee-balls (not rocks!) into the tarp to hold it in place
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when you do not have eyelets to hand. Rocks are pointy and damage the
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tarp. We have plenty of bungee-balls - find them.</p>
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<h2 id="main">Main roof tarp</h2>
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<p>Since 2015 we have had one really big tarp. This covers the whole
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sleeping area from front to back. It is set up so that essentially the
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whole bivvy apart from the water-tarp area is covered. The 2015 tarp
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was just about wide enough to span the width of the bivvy (i.e. the
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right size (15x6m)). The 2024 tarp is 3-4m wider than the bivvy, so
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has to be folded along the long axis to work. It is 15mx10m. </p>
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<img src="i/bivirig.jpg" alt="Drawing of post-2024 tarp layout" width=800>
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<p>Get out the (heavy!) big white tarp. The long edge goes from front
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to back of the bivi. The basic position is that it goes all the way to
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the right wall, partly 'underneath', and the left hand edge crosses
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the steps up the middle, covering the whole width at the back. The
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back edge reaches the floor behind the top 3-person flat area at the
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back entrance. The front edge comes down to ground level. Someone may
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have written 'front' and 'back' on the tarp to initially orient
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it.</p>
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<p>So start by opening it out to full length over the sleeping areas
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to the right of the steps, and folding 3.5m of the right hand edge
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back over on top. This needs to be reasonably neat and square, as you
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can't get to it later. Then pull the folded RH edge close to the
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wall. Sequencing the ropes is a bit tricky: you need the tarp vaguely
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in place, then install the four main ropes to lift it up. Then
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finalise the tarp position and tension it.</p>
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<p>Once the tarp is somewhat spread out, get the 4 main ropes in place
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underneath it. Use the anchors shown on the diagram that are known to
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work. The secret to the central rope '2' is _not_ to use the obvious
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ceiling bolt which is hard to reach; instead tie the RH end of rope 2
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to a tension rope '5' above the steps. This allows the tarp edge to
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come further left and run square to avoid sagging. Tension rope 2
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(with rope 5) first, then 1,3,4 to lift the tarp up and ensure it is
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neatly spread. You will need bungee-balls to hold the RH edge of the
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(folded) tarp in place. To get good tension on the main lines thread
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them through a maillon, and tie off on another bolt. You don't need to
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add any new ones - there are more than enough bolts now.</p>
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<p>At the left-hand end of rope 4 the tarp gets scrunched round the
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anchor. This is fiddly to get it all to hang nicely. The objective is
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to get the whole tarp taut enough and square enough that almost all
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the water runs down the top and out the front, rather than collecting
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in 'buckets', which then drip. That means that it has to be fitted
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quite 'flat'. To make this theory actually work, add extra lines in a
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zig-zag pattern between the main ropes so no buckets can form. Don't
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tension the early ones too hard as they distort the main ropes - it's a
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balancing act to get the tension everywhere right.</p>
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<p>To keep the electrics dry the edge of the tarp is held taut with string to concrete screws in this area.</p>
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<p>At the front edge the tarp lays over rocks. Put some padding
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(karrimat/old tarps) over the rocks to avoid damage to the new
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one. Lay rocks on the edge on the RHS. On the LHS use string to tie
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the front edge down. </p>
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<h3>Rear entrance tarps</h3>
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<p>This is the hardest part to get right. A couple of judicious
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bungees tied up high at the back wall will stop 'buckets'. [More detail should be added here]</p>
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<h2 id="water">Water tarp</h2>
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<p>Use a long/thin (2x5m) waterproof 'logpile' tarp. It is hung
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between two side longitudinal ropes, with lots of bits of string
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attaching the eyelets to the side ropes. Aim to hang it under the hole
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in the roof, and far enough forward that water off the front falls
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onto the 'water platform' (not into the food boxes). We now put two of
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these up to avoid drips and add water-collecting redundancy.</p>
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<p>It's easiest to approximately tie the tarp to the side ropes with
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adjustable knots, then put the ropes in place, adjusting as you
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go. The outer line ends up too high to adjust once properly in
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place. Adjust it to catch as much of the water falling through the
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hole as possible, and slope gently, but consistently downwards.</p>
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<p>The funnel/filter is hung below the end of the tarp where it will
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get nearly all the water and is much easier to
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hang/adjust/unclog.</p></body>
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</html>
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