There are a couple of important issues you should address before setting out on your (first) vol bivouac, weight is one of them. Weight is generally not that much of an issue when flying, as long as you are in the right weight range of your glider. When hiking however, it always is. You will get away with carrying an excessive load for a while, but it will become a burden eventually. This burden is likely to result in all kinds of complications that you could have done without. Ensuring your kit has the right weight, makes everything bearable. Even under difficult conditions. I do not know which load is right for you, since your physique is likely to differ from mine, but I do know what I am capable of. Writing down some general observations, as well as my experiences could help you in getting it right yourself.
Most people I have met, seem to be comfortable with a load of up to 14 to 16 kg during long hikes. They would love to have less weight though, especially when going up and down a lot. I have no problems to mention of when walking with about 16 kg on my back for days. Maybe you prefer less weight or are capable of carrying more. A person weighing 60 kg is unlikely to experience a 15 kg backpack in the same manner as someone weighing 90 kg, assuming the additional weight is caused by bones and muscles rather than fat. There are trained professionals that manage to carry 50 kg for days, including heavy and normally useless items such as rifles, bullets, and hand grenades. It all depends on the shape you are in, how much hiking you will be doing, at which altitude, and for how long. Hiking in the Andes once, my 15 kg backpack was heavy, but bearable. Even at 5000 m altitude. It became almost unbearable after discovering that I had made a navigational mistake and needed to turn back. The hike up to a pass at 4500 m altitude, which I had crossed without problems ten hours earlier, became a major battle that lasted several hours. It should have taken 20 minutes or so.
Hiking with more than 16 kg is likely to change your backpack into a burden, especially at higher altitudes. A burden that could cause you to do silly things such as continuing to fly while a thunderstorm is raging nearby. Being almost there, you prefer flying rather than walking the last miles of the long trip in torrid rain. Been there, done that. A heavy load is mostly felt when hiking up. That is why I might prefer battling my way out of a rotor or similar dangerous situation after a failed transition, instead of just landing safely and hiking up again. There are no excuses for this kind of behaviour, other than plain stupidity. Having a load that balances your plans and capacities, is likely to keep everything more safe and fun.
Just an evening flight
Do not focus on vol bivouac and cross-country too much. It will turn you into a boringly obsessed pilot that has forgotten how wonderful any flight is. It is fun to amuse yourself during the more regular flights, without having to think about the weather tonight, where to sleep and what to eat. Sharing these flights with a few friends makes it even better. You are likely to temporarily run out of (flying) friends when going for more than an ordinary cross-country trip. The further you go, the less likely they are to follow you. Of course, you will eventually fly into new friends this way. But a bit of simple soaring with your local friends could help you reminding that there is more to life than disappearing in the mountains for days or even weeks on end. Evening flights are excellent for this. Especially when there is restitution, followed by a chat, a drink, or a meal together.
Take along the bare necessities when going for an evening flight. In addition to my glider and harness, I will also take my helmet, gloves, and flight suit, but that is about it. About 13 kg in all, 11 kg for the flight equipment and 2 kg for the clothing. It might be a kilogram more if I also brought my sweater and a bit of water along.
A few days away
If your are planning to get away for a few days, then take along your basic vol bivouac kit. Mine weighs about 16,5 kg. Unfortunately, that is just over the previously discussed limit. It is a tiny bit too much for me to be comfortable with, but I still find it manageable. Keeping your basic kit under 14 to 15 kg or so, might be (a lot more) convenient compared to what I have. The additional weight in comparison with the bare kit is mainly caused by clothing for keeping me comfortable at high altitude, especially at night. In the presence of good thermal conditions, you are likely to find yourself flying in temperatures below ten degrees Celsius most of the times, even touching sub-zero values now and then. You better dress for the occasion. A cocoon helps as well.
Try flying the basic kit all the time, even if you only planned a local out and return that day. Since your body and mind are used to carrying this weight around, it will save you a great deal of 'breaking in' when starting your next vol bivouac. The greatest advantage however, is that your mind is less likely to be occupied by the return trip when planning or flying. Since you have all the things with you that are needed for a day or two, three in the mountains, you are bound to be looking for opportunities that could enhance your flight, rather than problems that could prevent your timely return. You are likely to discover a lot of new terrain this way, helping you to hone your skills and increase the pleasure. If there is one thing that I like even more than flying, it is flying new territory. This is especially rewarding if, after a careful analysis, everything turns out as expected and the flight just becomes heavenly.
Beginning vol bivouac pilots often get too optimistic at this point. Having brought their bare kit down to 12 kg or so, they add some food, a bit of water, a warm sweater, and contently set out on their first vol bivouac with a very comfortable weight. Everything remains comfortable, until the first rain, the first cold weather, the first lack of water, or the first hunger when hiking turned out to burn much more calories then anticipated. Take along good clothing and enough food and water. Your body will be thankful for this. As will the rescue services, since it frees up time for the real accidents out there.
The 16,5 kg weight of the basic kit does not include water and food. Count on a few kilograms if you want your mind free of food and drinking worries during your vol bivouac. Remember that each kilogram that you can shave of your basic kit, allows you to carry more water and food (in that order), without increasing the total weight. If you hadn't already, by now you should be beginning to understand the growing interest in really lightweight gliders and harnesses in recent years. It is interesting to note that after twenty years, pilots are getting back to their roots.
I prefer taking along real food such as bread, bananas, carrots, and nuts, rather than high tech outdoor food. I also shop at mother nature's biological boutiques for fresh vegetables and fruits each day. In case these are closed or any other emergency, I have a pouch (or two) with freeze-dried survival food for a two person meal with me. Do not expect haute cuisine from this food though, no matter what the labels promise. It could be a bit of a downer if you counted on the contents matching the marketing on the label. Most of it tastes terrible in comparison with real food, others a bit less. However, they will provide you that much needed energy (about 4500 to 4600 kJ of energy in my case) and weigh much less in comparison with the real food you brought along. Since they squeezed most of the water out of it, you need to bring along some in order to turn the contents of the pouch into something you can eat. Slightly more than half litre per pouch in my case. Take along more water than you normally would, when using this kind of food on your trip. I usually dine near a water source, in order not to carry the water needed for my dinner. What is the use of squeezing all water out of the food and then carrying it in a separate bag?
The value of sufficient amounts of water needed for your well being, can hardly be overestimated. Take along at least as much as you will be needing today and the morning after. Hunting for a refill is a comfortable affair in the cool early morning, and a pleasant distraction from all that waiting for the thermals to wake up as well. It certainly is less comfortable in the hot afternoon, when you like to be flying anyway. Even less so when you are hungry for food at the end of the day, but have no water to create your dinner. Not finding any, except after a two hour descent, you are cursing yourself for not getting a full refill in the morning. The energy you saved by choosing to hike up with a kilogram less weight than usual, is now completely erased by your troubled searching efforts as the sun sets.
A few weeks away
When leaving for a trip longer than a few days, I take the full kit. It weighs about 17 kg, just a bit more than the basic kit. This small difference is caused by some extra maps and money when extending my flights into Switzerland, and an extra bag to store provisions. The only significant difference between a trip of a few days and a trip of a few weeks, is the amount of food I take along. Carrying all the food needed for the whole trip right from the start, will too heavy. Practically infeasible. So, I take along enough provisions for about a week and restock when I (am about to) run out of things to eat. This period can be prolonged by eating from what mother nature has to offer me, economising on the food I brought along. In fact, long trips are often just shorter trips glued together by shopping. This somehow makes it all more manageable.
Be aware that if you take a lot of stuff with you, you could pass the upper limit of your glider's weight range. Depending on the glider, this could be a problem. Usually it is not. Your glider will probably behave a bit more dynamic when loading it heavier than usual. Most gliders I have tried like to be flown loaded though. And I like it as well. The glider is more solid in strong conditions, has better penetration, and is less susceptible to collapses. However, should a collapse happen, then be prepared that your wing might react more violently than you are used to. By flying the basic kit all the time, you get used to its behaviour. The step to a more heavily loaded glider when starting a (long) vol bivouac trip, will be smaller this way than when flying a (much) lighter than basic kit.
The full kit
All items that I carry are listed below, including their weight in gram. Most of them fit in the backpack, some go in the extra bag on top, and some are strapped to the sides. The precise distribution depends on the weight of the items concerned. I try to get heavy items as close to my back as possible, at shoulder blade level. Lighter items go in the bag on top, in the hip or side pockets, or get strapped to the sides or back of the pack. For example, bananas get stored in the side pockets. Clothing that needs to dry while I am walking, hangs from the sides and the back. My mattress is strapped to the back, since it takes up to much valuable space inside the backpack. This has the additional advantage of protecting the backpack against abrasive forces at work (especially when finding my way through dense vegetation).
The listed clothing concerns the items I will be carrying on my back when hiking, i.e. nearly all clothing. I will be wearing as little clothing as possible when hiking (even in winter), since the hiking gets me warm enough and soaks the clothing I wear with sweat. In order to obtain the full weight of everything I take along, add the weight of a thermal shirt and slip, trousers, hiking socks and boots.
I could probably get rid of a few kilograms by using one of those ultra-light gliders or harnesses, but for the moment I have chosen not to. A sleeping bag, tent, and full first aid kit are missing as well. If you would like to know why the full kit is assembled as it is, then have a look at the corresponding sections on equipment, clothing, food, and water.
This concerns all the stuff other than clothing and food:
The following items protects me from the weather and other environmental issues:
I might take the following items along in order to keep the engines turning:
These are the items I might take along, depending on my mood, conditions, and time of year: