Bridget Griffith  -  President

Benjamin Berry    - Vice President

Joseph Attwater  -  Treasurer

Foreword:

    Hello all you URI outing club members! Anyone having questions about different types of packs, and what’s right for you, and/or related questions may find this useful. This paper was written during my semester in Australia. Some words like “torch” (flashlight), might not be understood by all. If there are any questions, email me at: gvas9158@postoffice.uri.edu

Rucksacks (Backpacks)

By George L. Vasiliades

    When packing for a bush walk, clothing and equipment considerations will be dictated by the weather and intended activities. Assuming that one would like to stick to a basic bush walk not including specialized gear (for activities such as rock-climbing or caving), there are a few general rules for space and weight efficiency. These rules pertain to ways in which to minimize the burden on one’s body, specifically the back. 

Rucksack and Rucksack sizes 

    Some of the literature I’ve come across that used the word "rucksack" referred to packs that didn’t have a frame. Rather, these packs had only a layer of foam to protect the wearer’s back from any protruding points from within the pack, and were not generally suited for a heavy load. But for the intents and purposes of this paper, I will use the words "rucksack", and "pack" as general terms to include internal and external frame packs.

    There is a wide range of rucksack sizes to suit both male and female adults, as well as adolescents and young children. The carrying capacity is measured in cubic centimeters, liters, and inches, while the length is measured in either inches or centimeters. 

    The size of the appropriate rucksack will depend on the size and fitness level of the individual, as well as the duration of the trip. Literature I’ve come across has suggested that for a fit adult, either male or female going on a weekend trip, a 3,500 - 4,500 cubic inch pack should be adequate. A longer trip of a week or more, or winter camping, will require a bigger pack, usually in the 5,500 - 7,000 cubic inch range.
Properly measuring a pack is very important. This is done by measuring, "... from the seventh vertebra (the bony protrusion at the base of your neck between your shoulders) to the small of your back (level with your hipbones). This measurement will usually place you into small, medium, or large suspension groupings.

    Rucksacks generally come in three styles: "A" frame, parallel, or a type of hybrid sometimes referred to as a T-Bar parallel. The "A" frame is the most stable because it has a fixed harness, as opposed to an adjustable one as found in the other two types. Within these three styles of rucksacks, there are two main types, internal and external. Internal frame packs contain a support system on the interior of the pack consisting of aluminum or carbon fiber stays running from the top of the pack to the hip belt. The function of these stays is to transfer weight to the hips. Advantages of internal packs are that the weight is kept closer to the body, which enables one to more through the bush without getting caught on shrubbery, branches, etc. Weight is also balanced quite a bit better, as the internal frame improves the synergy between the pack and the person.

    External frame packs were the forefathers of frame packs. They are much more rigid than internal frames, but also provide great support. One might opt for an external frame when traveling in areas that are extremely hot, as the pack is away from the body which allows air to flow between. Also, when economics are an issue, externals are usually cheaper. The downside is that most of the weight is carried very high, which would make it a bit more difficult for a woman to carry for long distances.

    Rucksack materials may also be a consideration. These materials are nylon, polyester, and canvas. Nylon packs are very abrasion resistant and strong, but are more susceptible to UV break down over time. Polyester packs also have good UV protection, but are not quite as strong as nylon. One drawback consistent with both packs is that stitch holes in both materials stay open when punctured, thereby allowing wetness to permeate the pack. Canvas on the other hand expands when wet which closes up these holes, making it the most water-resistant pack. Packs made of canvas are also very good for long-term use. Lastly, a polyurethane inner layer may be found rucksacks of all materials. This increased the strength of the fiber a bit, while aiding waterproofness. While this is a great feature, it is important to note that over time, this layer delaminates due to constant manipulation of the pact, (i.e., going in and out of the pack to access items).

    After having found a suitable pack with regards to size, style, material, and support type, one must fine-tune the fit using the special features of the pack. These features are straps that tighten up any loosely fitting areas, and aid in proper weight distribution and overall comfort. Most of these straps are either stabilizers, or compressors. The stabilizers are for the hips, shoulders and sternum. These features do not differ for males and females, but females may have one additional strap on the hip belt, above the stabilizer. This is called a profiling strap and will prove useful for women who have a bit more shape to their hips. If pulled tight, this will allow more of the weight to rest on the hips, rather than constantly having the pack slide down. Compressor straps will just lessen the amount of unused space, and pull more of the pack’s weight into the body.

    Other important features worth mentioning are the lumbar pad, which provides support for the lower back, the hip belt which fits around the hip bone, supporting the brunt of the pack’s weight, and the haul strap which is used to aid getting the rucksack on and off.

Packing Principles for Weight Minimization and Distribution

    A fit, solidly built adult should carry no more than 30% of their body weight. An adult of slight built should stick to 25% of their body weight. Adolescents should also follow this percentage, while youth (pre-pubescent) or unfit adults should carry no more than 20% of their body weight. It is imperative to remember that unfit children will suffer far more than unfit adults, necessitating a lower percentage of gear to body-weight ratio to avoid dangerous situations.

Remember: Only take what is absolutely needed! The lighter the pack, the better and safer the trip will be!

    For the most part, gear should be distributed throughout the rucksack according to weight, mass, and necessary accessibility. Lighter, bulky items should go in first (in the bottom of the pack). These items would include a sleeping bag, towel and clothes. While the sleeping bag goes across the entire bottom of the pack, the towel, clothes, etc., should be somewhat away from the body. Heavy items should be kept toward the upper portion of the pack. These items would include the stove, food, extra bottles of water, the tent, and any loose gear. Unlike the light items, these things should be kept closer to the body, i.e., resting as close to the back as possible. If the fuel bottle is kept in the pack, it should be well away from food in case of leakage. The best spot for the fuel, however, is on the outside of the pack in a pocket.

    Items to be kept in outside pockets, or at the very top of the pack for easy access would include: nylon water-proof pack cover, torch, map, compass, utility knife, lighter or water-proof matches, first-aid kit, rain gear, snacks, jumper, beanie, sunnies, sun screen, camera, GPS, swimmers (optional), mobile phone, toilet paper & trowel, and toiletries. The sleeping mat can easily be strapped to the outside bottom of the rucksack.

Access and Waterproofness

    Access can be dealt with relatively easily by remembering the cardinal rule of packing, which is, “last in, first out”; meaning that the things that will be needed during the bush walk should be either in side or top pockets, or packed lastly toward the top of the rucksack.

    Contrary to some literature on waterproofing packs, I have found that rubbish bags can be used inside the pack as long as they are of a heavy gauge. Ideally, heavy zip lock or waterproof bags with plastic clips should be used for every piece of clothing, and any equipment that would be ruined or marred by wet conditions. If zip lock or clip closure is not available, it is best to use rubber bands rather than metal ties, as the metal may pierce other bags in the pack allowing permeability. While treated nylon pack covers greatly reduce the likelihood of saturation of the pack’s contents due to inclement weather, one should assume that no one system is full proof. As such, utilizing multiple layers of waterproofing is the best preventative measure.

What to Pack

    As mentioned at the beginning, these items (and quantity of items) will vary considerably depending on length of trip, and climate of the area. There are, however, those items necessary regardless of these factors. These are: sleeping bag / mat, tent, water & filter or purification tablets, both waterproof matches and lighter, stove / fuel, cookware / mug / utensils, utility knife, food, first-aid kit, map, compass, torch, toilet paper / trowel, extra re-sealable bags, toiletries, small towel, and environmentally safe soap.

    Necessary clothes to bring include: underwear, synthetic fibred thermals, rain gear, socks / wicks, t-shirt, wool or fleece jumper, and a wool or fleece beanie.

    Leader’s Additional Items: These items may include, but are not limited to: emergency flares, group first-aid kit, water filter / purification tablets, extra torch.  

Growth and Motor Considerations for Weight Carrying with Youth

    “Youth” as pertaining to bush walking can be split into two groups: Adolescent and pre-adolescent. Differences regarding the sex and age of the individual must be understood and dealt with accordingly.

    As previously stated, pre-adolescent children should only carry about 20% of their body weight. This figure refers to both males and females. Frequent rest periods are required.

    Adolescence is when gender differences come into play. Due to growing bones and muscles, youth (especially males) at this age tend to be clumsy, which should be taken into account when considering weight. As such, the motor coordination of an adolescent should be watched when walking close to cliffs and the like. In addition, metabolic rates are very high, which require very frequent stops, and ample hydration. Weight of rucksacks should not exceed 25% of total body weight. Menstruation issues for females must also be addressed.

References