What is a flat tarp?
A flat tarp is square or rectangular in shape, has flat edges, and 90 degree angles in the corners. They are wonderfully versatile and can be set up in all sorts of different shapes depending on weather conditions and terrain. Here are some great example pitches from tarp maker, Tera Rosa Gear, but there are many more variations possible. The tarp shown in this video is their Prospector model.
What is a shaped tarp?
Shaped tarps are not square or rectangular and usually have a curved ridge line or curved side edges. There are many different models and shapes that fit into this category. Some good examples include the Mountain Laurel Designs Duomid, the Zpacks Hexamid, and the Gossamer Gear CubicTwinn, shown below. While the shape in the Duomid and the Hexamid is obvious, the curved edges of the CubicTwinn run between the two ends of the top ridgeline, and all four edges have a gentle curved shape. Hexagon shaped hammock tarps also fall into the shaped tarp category.
What is a catenary curve?
Catenary curves have gentle U-shape, like the cable on a suspension bridge. Shaped tarps are cut with these curved edges because they provides a tighter pitch and saves some weight because the resulting tarp has less fabric. A lot of tent flies are also cut using catenary curves.
What are the advantages and disadvantages of a flat tarp?
Flat tarps can be set up in a wide variety of shapes depending on the weather and surrounding vegetation or terrain. They can also be pitched very low to the ground in high winds. Due to their simplicity, they are generally much less expensive than shaped tarps and can be used for other purposes beyond camping. They may also provide more usable shelter space than a comparably sized tarp with curved edges, depending on their pitch.
Flat tarps tend to be a little heavier than shaped tarps because they use more fabric, and it is a little harder to get a drum tight pitch with them. There’s also a bit more difficult to pitch because they’re so many different ways to set them up, and choosing the best pitch for a particular situation takes a little practice.
What are the advantages and disadvantages of a shaped tarp?
Shaped tarps can be optimized for specific weather conditions or terrain. For example, studies in the Antarctic have shown that a pyramid shape tarp is the most stable structural shape in high wind. They’re also very good for use in winter when you want high angled walls to shed snowfall. Shaped tarps are easier for beginners to set up and obtain a tight pitch with. Further, the use of catenary curves can reduce the weight of a tarp.
Shaped tarps are not as flexible as flat tarps because they can only be pitched in a relatively small set of configurations. The use of catenary curves also the edges reduces the amount of usable space they provide and they can be challenging to set up in tight quarters, such as dense forest, when there is not enough room for a full setup.
High standing tarp shapes can also suffer from reduced interior volume in high winds because it’s not possible to pitch them as low as a flat tarp. Finally, shaped tarps tend to be a good deal more expensive than flat ones because more labor is required to manufacture them.