expoweb/handbook/bivirig.html

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<h1>Bivi Riggin Guide</h1>
<p>Every year some poor bugger who has probably never done it before it
gets to rig the tarps and be responsible for any soggy miserable
nights that might result if it's not done well enough. Starting from
the bare space it's really quite hard to know where to start if you've
not done it before, so this doc attempts to provide some advice.</p>
<p>Note that this was written after Wookey+Joe's rigging effort in
2014. It is not necessarily optimum, but did seem to more-or-less
work. Feel free to improve it over time.</p>
<p>There are two essentially-separate jobs:
<ol>
<li>set up the
water-collecting tarp</li>, and
<li>set up the main tarps</li>
</ol></p>
<p>If there is any chance of it raining soon, start with the water
tarp, as you <strong>really</strong> don't want to miss it, and
setting up in the rain is rubbish.</p>
<h2>Terminology</h2>
<p>I will describe things as if standing at the bottom entrance looking
up, because that works for all three sections. So the
<strong>left</strong> wall is the
gear/stove/animal-hole wall. The 'back' is the top end of the bridge.
The 'front' is the main entrance.</p>
<img src="bivirig.svg" alt="Drawing of tarp layout">
<h2>Water tarp</h2>
<p>Use a long/thin (2x5m) waterproof 'logpile' tarp. It is hung
between two side longitudinal ropes, with lots of bits of string
attaching the eyelets to the side ropes. Aim to hang it under the hole
in the roof, and far enough forward that water off the front falls
onto the 'water platform' (not into the food boxes).</p>
<p>It's easiest to approximately tie the tarp to the side ropes with
adjustable knots, then put the ropes in place, adjusting as you
go. The outer line ends up too high to adjust once properly in
place. Adjust it to catch as much of the water falling through the
hole as possible, and slope gently, but consistently downwards.</p>
<p>In past years we have hung the funnel in the hole. This is a faff
and misses a lot of water. Just hang it below the end of the tarp where
it will get nearly all the water and is much easier to hang/adjust/unclog.</p>
<h2>Main roof tarp</h2>
<p>This is one large tarp covering more than half of the internal
roof. There are two main cross-ropes to hold it up, ties at the back
edge and 'knitting' to reduce sagging in the almost-flat central area.
The objective is to get it taut enough and square enough that almost
all the water runs down the top and out the front not collecting in
'buckets', which then drip. That means that it has to be fitted quite
'flat'. </p>
<p>Start with the big green 10x10m tarp. It seems to be near-enough
square so don't worry which way round you start. The basic position is
that it goes all the way to the right wall, partly 'underneath', and
the left hand edge is about in line with the steps up the middle. The back
edge lines up with where the roof rises at the back entrance.</p>
<p>So start by opening it out to full width on the wide central
bed-shelf. and pulling the RH edge close to the wall. Sequencing the ropes is a bit tricky, you need the tarp vaguely in place, then install the two main ropes to lift it up. Finalise th tarp position and tension it. </p>
<p>Once the tarp is somewhat spread out, rigging the ends of the two
main ropes - one across the front and one across the middle (passing
under the tarp). These are the two that take high loads. The rear
major rope has no real load - it just keeps things neat. Now tension
them to lift the tarp up and ensure it is neatly spread. The middle
rope attaches to the roof bolt just at the LH edge of the tarp. This
needs someone very tall, or sitting on shoulders, or something devious
with bivi string to pull it tight.</p>
<p></p>
<p></p>
<p></p>
<h3>Rear entrance tarps</h3>
<p></p>
<p></p>
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