Protected Site
As with any tarp or tent it’s worth choosing your camp site carefully. Somewhere protected from strong winds with a dry, comfortable and well drained ground, and a handy water supply that isn’t likely to flood. In high winds beware branches falling from trees. This photo shows a tarp pitched near a sink hole: a great location but rare in the UK.
Improves waterproofing!
Part of the rational behind using a ShellTA as well as a conventional waterproof is because all waterproofs degrade.
The most obvious reduction in performance comes because the water repellency of the outer fabric is lost, because of dirt, abrasion, water pressure or contamination with water softeners. This causes the fabrics to become saturated and the inside is likely to reach the dew point, causing condensation and a loss of breathability.
Conventional membrane waterproofs may also be punctured, membranes can crack, abrade and delaminate and seam tape can peel off.
Some of these problems only manifest themselves in extremely wet weather and the ShellTA gives you another tool to reinforce your waterproofs in those rare extremely wet conditions. It provides a “defence in depth”.
Improving venting with the ShellTA
When the inside of your ShellTA becomes wet (normal when layered over wet softshells in the rain) it tends to stick to inner layers that are already water logged. This reduces venting, insulation and wet weather breathability. However, when you wear the ShellTA over your sack, like a poncho, this seperates the fabrics and improves performance.
When you wear the ShellTA under your sack, ease the front fabric out from beneath your hip belt and shoulder straps to separate it from under layers.
What happens when the ShellTA fabric becomes saturated?
Like any waterproof breathable fabric, breathability stops when the fabric becomes saturated, however it remains waterproof. Wind will help breathability, even in the rain, especially if air is allowed to circulate through the ShellTA.
The fabric of my sleeve was wet before getting in the ShellTA
When you wear it over a wet waterproof the water tends to stick to the ShellTA, providing a useful drying effect. Once it is saturated this effect diminishes and air circulation beneath the waterproof canopy is the only way drying will continue.
Why use a lunch ShellTA when it’s not raining?
Although the ShellTA is made from a thin waterproof fabric, with little inherent insulation, two people sat together inside can share a surprising amount of heat that would otherwise be lost to the atmosphere. It’s also a very simple way of adding extra protection for your legs, without the hassle of overtrousers …and it doesn’t need to spoil the view: each person can open their side vent to peer out and breathe in the mountain vista.
Protecting a Casualty
It’s unwise to move an unconscious casualty (or even a conscious one, depending on the injury), but they may still need protection from the elements (once you have completed the ABCs of first aid). Most 2 person mountain shelters are not big enough to adequately cover a prone casualty but the ShellTA can be spread out as a waterproof blanket. Use whatever is available, pegs, rocks, sacks or volunteers, to hold it in place without causing any further discomfort to the injured person. Use all the resources at your disposal to protect the casualty and yourselves while waiting for rescue.
Two ShellTAs, zipped together in poncho mode create a shelter nearly 3m long, which can provide protection for a casualty and two first aiders.
(Large clan tents, mountain shelters or bothy bags are used by most mountain rescue teams to provide an environment for multiple team members to stabilise a casualty. The ShellTA is not big enough for this role.)
For more on First Aid please try this site.
Thanks to Glossop Mountain Rescue Team for this image.
Suspending from the hood
Large tarps can be made more stable in the wind by supporting the centre of the sheet of fabric. This is easy to do with the ShellTA: just larks foot a long guy line around the hood, below the cord lock and use a trekking pole as an external strut, to produce a large, unimpeded living space. The hood transmits the tension evenly around the long neck seam.
Two People for Warmth
Production ShellTAs are longer than this prototype.
In an emergency (or just to have lunch out of the rain) two people can sit down side by side in the ShellTA. This is remarkably cosy. Tuck the fabric beneath you to help prevent the fabric from flapping but allow a small amount of ventilation.
To minimise heat loss reduce contact with the ground and sit on something insulating (eg sit mat, rope or sack). Huddle together to minimise your surface area and use all the insulation you have before you start to feel cold.
Each person gets a zipped window for venting or to admire the view!?
Do you recommend using the ShellTA with overtousers?
ShellTA over FurTech Trousers
One of the advantages of using the ShellTA as a poncho is that it’s easy to pull it over your head to protect your body and legs, rather than struggle into over-trousers. This is particularly useful in sudden heavy rain and occasional squalls.
How much of your legs it covers depends on how tall you are, but even very tall people can often get away with just protecting their lower legs with gaiters.
In persistent bad weather or wintry conditions it is prudent to use overtrousers or water resistant softshell trousers beneath the ShellTA to keep the inevitable condensation at bay. In summer rain try using the ShellTA over shorts to stay cool.
ShellTA and Pile / Pertex
Pile / pertex softshells rely on being (relatively) warm when wet and quick drying. Body heat helps push moisture outwards when you are on the move, but this can seep back in when you stop and begin to cool. They can also be a tad warm as you climb out of the valley, even though their insulation is appreciated on cold and blustery tops.
The ShellTA adds an extra dimension to a Pile Pertex system, adding an option for warm and wet conditions, very wet conditions and providing shelter when you stop… all for less weight than a typical waterproof jacket and trousers.
A Buffalo sleeping bag system will also benefit from the ShellTA, used as a tarp for wet weather bivis.
Why not use press studs down the sides?
We decided to use zips to keep the wind out when using it in bothy mode and to provide a better seal in bivi bag mode. They make it a much more versatile product that can defend against really bad weather.
(Take care when using it as a poncho in high winds!… especially in rocky or precipitous terrain.)
Making a large tarp
Two ShellTas can be zipped together to make a large sheet about 280cm by 260cm. It can then be pegged out like a tarp. However, care must be taken not to put undue tension across the zips and this large expanse of fabric benefits from more than two treking poles as support. That said, a number of years ago on the Haute Route, we used two ShellTAs to accommodate four of us with just one trekking pole and several ice axes. At that time the zips didn’t match (they were prototypes) so we just overlapped them in the middle. We used them twice, the second time at over 3000m.
How have you supported the corners in the photos?
I’ve placed rounded rocks beneath two corners to provide more usable space inside. Make sure that there are no sharp edges to damage the fabric. It’s often possible to find rounded rocks near a water coarse.
Why use it as a bivi bag? Isn’t a tarp more comfortable?
A tarp provides much more living space than a bivi bag and is generally more comfortable to use. However, it’s easier to use a bivi bag on ledges, in caves,in snow holes or in high winds. And sometimes, when heavy rain is unlikely, it’s simpler and easier to use a bivi bag… and fall asleep watching the stars.
What colour is it available in?
The ShellTA is only available in Red, which is good for emergency mountain bivis.
How long should the guy lines be?
I cut my guylines quite long at 2.5 to 3m on the basis that it is easy to shorten them (or cut them in two for other things). I put a large figure of eight on the bite in each end to larks foot onto the a tie in point and for the peg. I often use the same guyline from two tie in points, one of which must be tied.
(The length and number of your guy lines depends on how you prefer to pitch your ShellTA.)
How should I tie a suspension cord to the hood?
First wrap the drawcord over the top of the hood and cinch it in. Then larks foot a loop in the end of the guy line around the hood below the cord lock. This stops any water getting in the hood and transmits the tension through the long collar seam through the fabric.
How much is it?
The ShellTA is £50 rrp. We may have to put the price up for the next production run as we are expecting an increase in the price of the next batch of fabric.
How heavy is it?
The ShellTA weights 530g including stuff sack. That’s lighter than most bivi bags or waterproof jackets, but it serves as either… and as a sack rain cover…. a mountain shelter…. or as a tarp.
What’s the packed size?
A bit less than 35cm by 10cm diameter. This shape allows it to easily slot into the side mesh pocket on many sacks.
ShellTA as a Tarp
With three sides low to the ground this arrangement copes with changes in wind direction. The site was chosen on the edge of a forest for wind protection. In very strong winds I would have chosen a pitch among the trees.
The stuff sack is used over the pole to prevent it wearing the fabric.
You can see from the picture that by supporting the hood more space is created inside and the fabric is held taut.
ShellTA as a Tarp
A shellTA pitched with three sides low to the ground, using two poles. This copes with changes of wind direction but tall users may find that their feet touch the fabric.
ShellTA Dimensions
shellTA as a tarp
The sheet of fabric used to make the ShellTA is 150cm wide by 260cm long.
- In poncho mode it extends 130cm front and back but can be shortened by use of the press studs.
- In bivibag mode is 260cm long but the ends are best folded in or cinched with cord making the useable space a little shorter (this is still longer than most bivibags).
- In tarp mode it measures 150cm by 260cm.
Joining ShellTAs Together
Two or more ShellTAs can be joined together by attaching adjacent zips. This creates
- Larger Tarps
- Tarps with a ground sheet (half tarp/half bivibag)
- Multi-person BiviBags
- 4 or more person Lunch/Emergency Shelters
When zipping two or more ShellTAs together for use as a tarp be careful not to create too much tension across the zips. You can avoid this by tying guy lines from the eyelets in the zip flaps to take the majority of the force.
Hydrophilic Membrane
Inside a shellTA
The ShellTA is made from a waterproof and breathable lightweight hydrophilic membrane with sufficient hydrostatic head to allow you to sit on wet ground.
This fabric has the advantage of drawing water off layers that are worn beneath – which are typically already wet by the time you pull the ShellTA on. It helps dry these layers by spreading this moisture over a large well ventilated area.
For more on breathability please see this link.
Will the zips leak?
The zips are covered by dual flaps.
In poncho mode any water that creeps past these flaps is well away from the body and isn’t usually a problem.
In bivibag mode make sure that the zips are low and to the side and that the flaps don’t form a gutter to direct water inside. In very wet and windy conditions it may be prudent to sleep with the zips almost below you: A sleeping mat will prevent water penetration. Silicon sealer can be applied to the zip seams if you intend using the ShellTA as a bivibag in very wet weather.
In mountain shelter mode most people will be wearing a water resistant jacket inside and small amounts of rain coming through the zip will not be a real problem.
Can I seal it as a bivibag?
breath has a large water content
The ShellTA fabric is not a vapour exchange fabric and should not be completely sealed. However you only need a small hole at the face to prevent asphyxiation.
Directing your breath out of the ShellTA (or any bivibag) will reduce the liklihood of condensation forming inside as the exhaled breath has a very large water content, as I’m sure you’ve noticed when you breathe out on a cold day.
Will the ShellTA keep me dry?
Don’t believe manufacturers that claim their products will always keep you dry. Even if the fabric is 100% waterproof the inside can easily reach the dew point due to cold bridging, causing condensation on the inside.
To prevent condensation the temperature and/or pressure must be raised or the humidity reduced. The massive venting of the ShellTA can reduce condensation build-up, but there will inevitably be times that the inside gets wet – it’s just the laws of physics.
I’d recommend using the ShellTA as extra protection for Hardshells or water resistant Softshells unless conditions are warm and wet, when you may want to use it over shorts and T-shirt.
When the ShellTA is used over other water resistant layers it can reduce dampness inside them by drawing water off the surface and improving breathability. Please see this post about cavity wall construction.
Is the ShellTA waterproof?
The ShellTA is manufactured from waterproof and breathable fabric and the major centre seams and hood are taped. The side zips are protected by overlapping flaps but are not taped.
When using the ShellTA as a bivibag I recommend that you use a sleeping mat to provide extra protection from saturated ground. The side zips should be positioned low, to the side, so that water runs off them.
ShellTA as a Changing Room
The conventional 3 layer clothing system is sometimes confounded by worsening weather: How do you add insulation under your waterproof without getting soaked when it’s pouring down?
The ShellTA can be used as a changing room, giving you enough protected space to take off your waterproof jacket and add another mid layer.
Changing Layers Inside a ShellTA
One summer, years ago, I had a quick and sweaty march to the top of Skiddaw. Joining many others at the summit we were hit by a sudden squall with heavy rain. The scene was frantic as everyone scrambled to pull on waterproof jackets and over trousers, but most people were soaked to the skin. This was the first time I used an early prototype ShellTA as a changing room, swapping shorts and T-shirt for waterproofs and emerging, changed, as if from a chrysalis.
ShellTA as a Tarp
shellTA pitched as a tarp, supported by the hood
With the zips open and the hood sealed with the drawcord the ShellTA can be pitched like a tarp… in a wide variety of ways.
It is often useful to use the hood drawcord to support the centre of the ShellTA, creating more room inside and increasing the wind stability of the structure. In the above picture the corners have been propped up with a couple of stones to improve internal volume and keep the foot of the sleeping bag dry.
using the stuff sack over the end of a trekking pole
If you are supporting the tarp by propping a walking pole beneath the fabric I recommend that you use the stuff sack over the handle end to reduce wear on the ShellTA fabric.
Like all tarps the ShellTA can be pitched high for more living space or low for better wind protection.
It’s easy to sit or lie under a tarp wearing your waterproofs and giving them a chance to dry out (FurTech and Paramo clothing dries quickly in such a situation). A tarp provides a protected cooking area and is easier to live in than a bivi bag. It has much more space and you can sit or lie inside without taking your shoes off, unlie some tent designs. However, in very bad weather it is prudent to use a water repellent sleeping bag so that splashes and condensation don’t saturate your insulation.
ShellTA as a Bivi Bag
Open the ShellTA zips to form a large sheet and re-connect the front left poncho zip with the front right. Do the same with the other zips and you have a long tube.
Cinch the drawcord around the hood to seal it.
The bottom end can be sealed by elastic or cord, or the fabric folded and secured inside with press studs to discourage water ingress (this option increases venting). I usually secure the top end with press studs to form a large flap over whatever I’m using as a pillow. It is important that air is allowed into the bag so that you don’t suffocate. In wet weather leave the top fabric unfolded so that it is longer than the bottom, and covers the face. By breathing outside the bag you will significantly reduce the risk of condensation inside.
ShellTA as an Emergency/Lunch Shelter
Production ShellTAs are longer than this pototype.
In the wet and blustery British hills it’s sometimes useful to get undercover for lunch stops (and emergencies). Sharing body warmth inside any shelter makes an enormous difference and large group shelters have become standard equipment for Mountain Rescue Teams and Instructors. This was the original purpose of the shelters I made. It’s also worth pointing out that if you are trying to reduce heat loss then you should maintain minimum contact with the ground, ideally using a sit mat, rucksack or rope as insulation beneath you.
The ShellTA will seat two people inside by simply pulling it over your heads and sitting down side by side (with zips closed in poncho mode). Arrange the fabric so that you sit on a small section and rest your feet on the remaining fabric to prevent drafts. I find it best to take my sack off first and put it between my legs so that I can access it inside the ShellTA and I use a sit mat to add insulation.
The side by side seating in the ShellTA makes it comfortable to sit on the leeward side of a ridge line or hill, out of the wind. Each person can vent their side of the ShellTA using the zips, or look out at the clouds skidding past. Even when the sides are zipped up, the hood can act as an air vent.
ShellTAs can be zipped together for larger groups. Two will generally accomodate 5 medium build people.
ShellTA as a Poncho
ShellTA over a sack
Ponchos are popular in other countries for a number of reasons:
- They offer rain protection and massive venting for summer rain and are a joy to wear over shorts – they keep the majority of your legs dry.
- In blustery weather they can be worn beneath your sack to stop the fabric from flapping too much.
- Compared to a waterproof jacket and trousers they are very light.
- It’s easy to access pockets on garments worn beneath the poncho.
- When worn over your sack it will keep it dry.
The side zips on the ShellTA means that you can adjust the venting depending on the wind direction and these allow it to be used in severe weather. (Please take care on dangerous and rocky mountain terrain by tucking the flapping fabric underneath your sack.) The side zips also allow it to be used as a bivi bag or two person mountain shelter.
The ShellTA is made from lightweight waterproof and breathable hydrophilic fabric which can aid the drying and breathability of hardshell and softshell under layers. Please see the Dual Protection category for more on this.
High Winds
Wearing a sack over the ShelTA
Be careful when wearing the ShellTA in strong winds in rocky terrain as its large area can act like a sail! To overcome this problem wear your sack over the top to trap the fabric. As you can see from the image this also shortens the poncho. You will find it still offers more air circulation than conventional waterproofs due to the shape of the “sleeves”.
Warm Rain
Massive venting and great air circulation, especially when worn over a sack, make the ShellTA ideal for warm rain. Wear it over shorts and T-shirt for maximum cooling. Use gaiters over boots or allow lightweight trainers to get wet.
Cavity Walls
Cavity Wall
British houses are built with cavity walls for a very good reason: it keeps the inside dry. If a single layer brick wall were used condensation would form on the inside because of cold bridging. The cavity prevents the inner wall from getting damp and airflow through the gap helps to remove excess moisture.
Layering a ShellTA over water resistant outdoor clothing (hardshell or softshell) works in a similar way, allowing the inner garment to breathe more effectively, especially where the two layers don’t touch.
Reinforcing a WindShell
WindShells with well maintained water repellency can cope with quite heavy rain for a short period of time. However, the thin fabrics soon chill with the cooling effects of the rain and condensation can occur on the inside or even amongst the weave of the fabric, which then saturates.
The ShellTA is not only useful for emergency bivis, you can use it over a WindShell in case the weather forecaster got it wrong. At 500g it’s half the weight of most waterproof jackets, trousers and emergency shelters.
Reinforcing a Softshell
Softshells have a wide range of abilities and some can be used in most British weather conditions. Hill goers are well advised to take some sort of emergency shelter: perhaps a large orange polybag, clan tent or bothy bag. The ShellTA not only provides emergency shelter but can add extra protection on those days when the weather forecaster got it wrong… and, at 500g, it weighs less than half the weight of most waterproof jackets, trousers and emergency shelter.
Reinforcing a Hardshell
Why, you may ask, would I want to reinforce a top of the range waterproof hardshell? Isn’t 20m of hydrostatic head enough!
The problem with all thin waterproof materials is a concept well known to building engineers: cold bridging. This is the condition when the inside of a waterproof barrier becomes chilled to below the dew point, resulting in condensation. It happens with all waterproof membranes, no matter how expensive, especially when the outer fabric becomes soaked with cold rain water.
Some manufacturers, notably FurTech, Paramo and Keela, have created garments that utilises an air gap to add insulation to their waterproofs, reducing this problem. Another solution is to add a ShellTA over the top to create a dual layer with a well ventilated region in between.
The side zips on the ShellTA allow you to tune the amount of air coming through. If you wear it over your sack it not only protects it, but increases the air gap over your shoulders. Even in blustery weather, when it is best to wear the ShellTA under your sack, the large volume and light fabrics, pumped by the wind, allow significant air flow around the body. The result is that the ShellTA can significantly improve the wet weather breathability of your waterproof hardshell and keep you drier.
A Prototype ShellTA
A prototype ShellTA
Like this ShellTA, this site is a work in progress. If you have any questions about the ShellTA please email sales@furtech.co.uk
What’s a ShellTA?
shellTA pitched as a tarp
ShellTA is a single product that can be used as a bivibag, tarp, poncho or 2 person mountain shelter.
Use it as an emergency shelter or bivi.
Use it for planned bivis as a tarp or bivi bag, in a cave or snow hole.
Use it to reinforce any waterproof or softshell clothing system in case the weather takes a turn for the worse. They can also be used over a conventional waterproof to aid breathability and help to prevent cold bridging - similar in concept to the cavity wall construction of a house.
Ponchos are popular on the continent for warm rain because of their excellent venting. Wear the ShellTA over your sack for maximum air circulation (and sack protection). Wear it under your sack in strong winds to prevent excessive flapping. The ShellTA protects the legs and is adjustable in length.
