Tarps have been around for a long time; probably as long, or longer, than all forms of tents. They endure because of their simplicity and their flexibility. Currently they are finding renewed popularity with the light weight hiking crowd and the hammock hangers.
As with anything, there are trade-offs associated with tarps in terms of size, shape, weight, material, cost, and the environment one expects to encounter. Is the tarp’s primary purpose to provide shade or to provide rain protection? While weight and size are of paramount concern to a backpacker, when the weather turns really bad and you have to hunker down for any length of time, a good size tarp makes life a lot more bearable.
Small Tarp Shapes
The square and the rectangle are the traditional tarp designs for good reason. They offer the most flexibility and relative coverage for any given square footage of tarp. In the hammock camping realm, hex shaped tarps, and a variety of tarps with catenary curved edges on the basic shapes have emerged.
Relatively small rectangles, on the order of 5×8.5 feet, when hung on the diagonal, will provide basic overhead coverage for typical gathered end hammocks. Hennessy hammocks use this approach, as do those individuals who use extended length silnyl ponchos over their gathered end hammock models. They provide minimal coverage and require careful site selection to minimize wind. They also require nearly perfect centering to ensure coverage on all sides of the hammock. While this approach minimizes tarp weight, it requires careful site selection to avoid the wind and/or it may require use of a weatherproof bottom cover, which may negate the weight or cost savings of the smaller tarp. The approach has inherent risk for all but the mildest or arid environments.
Some hammock makers provide generous 8×10, 10×11, or 10×12 tarps. This popular solution provides super coverage in all weather conditions. It is a great asset to have when the weather turns crummy for an extended time. Additionally, these tarps are typically made with abundant tie-out points which make them great tarps for any backpacking purpose or for ground shelter use.
An 8×8 square or diamond tarp is a great answer for the hammock hanger and/or soloist ground camper. When pitched on the diagonal over a hammock its 10 foot plus ridge line provides about a foot to one and a half feet of coverage beyond the ends of the hammock. The sides go out at strong 45 degree angle to a single tie out point on each side. This is in contrast to the roughly 30/60 degree angles of a small rectangular tarp pitched on a diagonal. The tarp can be hung at 4.5-5 feet above the ground and the side(s) can still be staked to the ground. The down side totally protects the hammock from perpendicular wind. When tied straight out or near straight out it provides up to 64 square feet of coverage. Additionally, when a well selected, sheltered site is used in summer heat, this type set up provide max ventilation and coverage for a pleasant camp under otherwise hot, sticky, close conditions.
Hex shaped tarps have emerged as a middle ground between the square hung on the diagonal and rectangles. Depending on the overall size the hex frequently is a compromise that is less weight and protection than the rectangle yet more weight and protection than the square or diamond. The hex tarp requires two tie outs per side, and generally pitches taut. By comparison, the rectangle frequently requires three tie outs per side while the square or diamond requires only one tie out per side.
Sag and Flapping
Probably the most aggravating thing about tarp camping is a poorly pitched tarp flapping and vibrating in the breeze. There are a number of ways to deal with this problem. First and foremost – the best pitched hammock covering tarps are tied to the tree vice the hammock cord. This eliminates tarp sag when one enters the hammock. Tarp sag, alternatively, can be greatly reduced and possibly eliminated with use of shock cord or surgical elastics on the tie-out lines and/or the use of weights (such as Nalgene bottles of water). However, tying the tarp directly to the trees is less hassle and will provide a better pitch.
Now for the debate on the catenary cut. This popular tarp feature, aimed at reducing sag and flapping, has good and bad points. When the ridgeline is a catenary cut it provides, in its optimum, or near optimum angle, a super taunt tarp. This virtually eliminates any flapping. Some say, “It turns the tarp into a hummer vice a flapper in storms”. The drawback is that it is only effective in the optimal pitch and it becomes extremely floppy and sloppy when pitched high and flat or as a single plane, shed roof. It often eliminates other ground pitch options, beyond the optimum angle, altogether. This style of tarp is only for the individual who plans to use it the same way all of the time. It eliminates, for practical purposes, most of a tarp’s flexibility features.
Catenary curves, however, can be introduced on the sides of tarps with limited to no loss of flexibility. When curves of this design are added the casual tarp camper will find it easy to achieve a taut pitch. The drawback is that these curves will reduce the area of coverage by the material removed in creating the arc. It follows then, that catenary cut tarp edges are best when shallow in design. Alternatively, when full coverage is required a slightly larger tarp is often the base of a finished catenary tarp. Such an approach is weight neutral with a slightly smaller hex or rectangle providing equal square footage of coverage. Greater tautness in pitch will have some additional cost generally for equal coverage. An experienced tarp camper with an adequate number of tie outs can normally achieve the same or very close tautness without the added cost of catenary curves.
Flat rectangular edges may be combined with catenary curves on adjacent sides. Such tarps often provide additional pitch option; retaining the flexibility of the straight edged rectangle and providing the additional tautness of the catenary sides. They may just be the best of both worlds.
Self Tensioning Lines
Many ultra-light tarps are made of 1.1 ounce rip stop nylon that has been impregnated with silicone, often called silnyl. This material tends to stretch slightly in rain or even with heavy dew. When it stretches, the tautness is reduced and, if windy, the flapping begins. To correct this condition one must adjust or tighten the tie out lines. This is exactly the opposite compensation from decades past when canvas tent lines were slacked to keep them from ripping during storms. These adjustments can be required one or two times a night as conditions dictate. The simple solution to end these sleep disturbances is to use self tensioning lines that adjust automatically to compensate for silnyl stretch.
Large Tarps and Hammock Tents
With the advent of larger hammocks, the Hennessy Explorer and Safari models, Claytor Jungle Hammock and the Jacks ‘R’ Better Bear Mountain Bridge Hammock larger tarps and even full hammock tents have come into vogue.
Larger hammocks frequently require 10×12 tarp coverage or the slightly reduced 11×10 size popularized by Speer Hammocks and JRB. These tarps have several features such as catenary cut edges and in the case of the now out of production Speer Winter Tarp, catenary darts. Both of these tarps are in the 18 ounce range and both are capable of providing full side coverage as well as the forming near four sided hammock shelters. As an added bonus the JRB 11×10 can be pitched as a Baker Style lean too for full side weather protection and center hammock walk up convenience. They are excellent choices for extended use when weather is unpredictable and when conditions may require extended stays. Yet, at just over one pound, they remain very viable hammock shelters for the light weight backpacking community.
The JRB Hammock Hut, now out of production, was the original hammock Tent. It was a full hammock shelter with four sides, doors, ridge vents, protective beaks, side tie ups and dual bottom reefing points. It accommodated a hammocker plus an adult and a child or large dog on the ground. It provides the best privacy and full weather protection available for any gathered end hammock. While it will work with the BMBH the addiditional roof point tie outs must be used and care on entering and exiting the hammock must be exercised as the fit of the BMBH spreader bars is close to the side walls. The Hammock Hut itself weighs only 28 ounces, and is under two pounds including ridge lines, Self Tensioning Lines (STLs) and pegs.
On a final note about shapes, here are many special purpose tarps. Some are parabolic, some have catenary ridges only and some have cantenary ridges and catenary sides, some are hex and some are octagonal. All of those with a catenary ridge included will have optimal and sub-optimal pitch issues.
There are few being manufactured with high tech materials such as polyester sail cloth and cuben fiber. While these materials will reduce weight carried a little or a lot they will increase costs likewise; a little or a lot.These materials are often more translucent and some report noisier. Long term durability is an unknown as of the end of 2011.
As a post script, remember a tarp can be made from a painter’s plastic drop cloth with pebbles in the corners and mason twine for tie outs. Weight, durability, and style may be valid considerations. When equipping a hammock camp, tend to hammock selection first, bottom insulation second, then optimize your tarp selection. This old standby, the painter’s drop cloth, approach will get you by until then.
Hope this helps you to understand the tarp… beast and beauty.