Tent, tarp or hammock: matching shelter to terrain and skill

Three shelter systems, three different bills. A tarp is the lightest and asks the most of you: no insect protection without an inner or a bug bivy, and a pitch that has to be read from the ground and the wind every night. A hammock removes the ground and adds two hard requirements in its place, anchors and an underquilt. A tent costs weight and buys repeatability.

What each system is, and what it actually weighs#

Fabric weight is the number people quote and the least useful one. What counts is the mass of everything needed for a dry, insect free, wind resistant night.

Those ranges are what manufacturers publish, not measurements taken here. Run the arithmetic for a pair of walkers: two hammock systems at 1,200 g each is 2,400 g, or 1,200 g per person, where one two person tent at 2,000 g is 1,000 g each once fly, inner and poles split across two packs. The hammock is the lighter object and the heavier decision. Count the whole system in your base weight, stakes included.

What a tarp asks in exchange for the weight saving#

A tarp is a roof and nothing else. Everything a tent does automatically becomes a decision: where the wind is now, where it will be at 4am, how high to set the ridge, how far splash reaches, whether the ground drains. The ridge height trade is worth doing on paper. Take a 2.5 by 3 m tarp pitched as an A frame, so each side has 1.25 m of slope from ridgeline to ground. With the ridge at 0.9 m, the horizontal reach of each side is the square root of 1.25 squared minus 0.9 squared, which is 0.87 m: about 1.73 m of covered ground. Drop the ridge to 0.6 m and each side reaches 1.10 m, giving 2.19 m.

Lowering the ridge by 30 cm buys 46 cm of protected ground and removes most of your sitting room. That is the tarp argument in one calculation: pitch high in settled weather, pitch low and close one end in wind driven rain, and accept that you are lying down until it stops. The rest is site reading, which takes longest to learn and is covered in pitching and site selection. A tarp punishes a bad site far harder than a tent does.

What a hammock needs from the site#

Two anchors, roughly 3.5 to 6 metres apart, each sound and each protected by webbing wide enough not to cut bark. Below 3.5 m the suspension steepens and the hammock cannot develop its sag. Beyond about 6 m you carry strap and lose height. Suspension angle matters more than most people expect, because strap tension is set by trigonometry rather than feel. For a load hung at the centre, each side carries roughly the weight divided by twice the sine of the angle. An 80 kg person is about 785 newtons:

A tight, flat looking hang strips bark, breaks hardware and squeezes your shoulders. The 30 degree hang is comfortable because the fabric develops enough sag to let you lie diagonally across the weave, which flattens your back. Set the anchors so the loaded hammock sits around 45 cm off the ground, leaving room for overnight stretch. Wide webbing is standard practice because narrow cord cuts bark.

Why a hammock sleeps colder than the same night on the ground#

Two mechanisms, both against you. Air moves freely underneath, so your underside loses heat by convection to moving air rather than by conduction into still ground. And body weight compresses whatever you lie on to almost nothing, removing most of its thermal resistance.

This is the physics behind sleeping pad R-value, worked through in the pad R-value guide, minus the ground's own modest insulating value. The ISO 23537 thermal test is run with the bag on a mattress of specified resistance, which tells you that the standard credits crushed fill with nothing.

The fix is an underquilt: insulation hung outside the hammock where your weight never reaches it. Below roughly 18 degrees C that is not optional. A pad substitute fails in two ways: it folds and slides as the fabric wraps around it, and it insulates only the strip directly beneath you, leaving shoulders and hips out at the edges of the wrap. If you already sleep cold, read why you sleep cold first, because a hammock amplifies every factor on that list.

A bivy bag gets confused with shelter and is not one. It adds roughly 1 to 2 degrees C by blocking wind and trapping a thin air layer, and no living space.

A scoring matrix you can run before the trip#

Score each system 0 to 3 on the six things that decide the outcome. The scores below assume broken, forested, sloping ground, and a bug bivy for the tarp, because a bare tarp scores 0 for insects.

The matrix scores fitness, not weight, so a tent tops it by default. The decision rule makes it useful:

Double the two criteria that actually define your trip, rescore, then take the lightest system whose total lands within two points of the highest.

1. Summer forest, heavy insects, solo, low storm risk. Double terrain and insects: tarp 14, hammock 18, tent 20. The hammock is within two points and lighter in warm conditions, so it wins. Genuinely close.
2. Above the treeline, autumn, two people, exposed ridge. Rescore terrain for open ground (tarp 2, hammock 0, tent 3), double terrain and storm: tarp 13, hammock 11, tent 24. Not close, and not a judgement call.
3. Dry, warm, low insect season, experienced pitcher, open ground. Rescore insects to 3 across the board, and the skill row to 3 because it measures tolerance of low skill rather than merit: tarp 16, hammock 10 with no anchors, tent 18. The tarp is within two points and saves several hundred grams.

So tarp against tent is close in dry conditions outside biting season for someone who can pitch in the dark, and not close for a family in midge season on an exposed site. Hammock against tent is close in warm forest for one person, and not close above the treeline, on sand, in snow, or in any group where the shelter may need to hold somebody other than the person who pitched it. Tarp against hammock is barely a comparison, since every hammock needs a tarp anyway.

One thing is not close despite being widely assumed: fabric does not decide storm survival. Hydrostatic head under EN ISO 811 describes water column resistance, not whether a pitch holds at 60 km/h. See waterproof ratings explained, and tents in wind for what does decide it.

The failure modes each system has that the others do not#

Tarp only. The wind veers 90 degrees at 3am and the pitch is now broadside to it. Ground splash comes back under a low edge, wetting the first 20 to 40 cm of the sleeping area. One stake pulling out can drop the whole structure, because nothing in a tarp is self supporting. And there is nowhere to sit out an insect swarm, since a bug bivy only protects someone lying flat inside it.

Hammock only. No anchors, no shelter, and no way to improvise one if you left the pad at home. Underquilt gaps produce a cold stripe at the shoulder or behind the knee that is hard to fix in the dark. Dead branches overhead are a specific hazard, because a hammock puts you under the canopy by definition. Suspension and fabric creep overnight, so a hammock hung at 45 cm can be resting on the ground by morning.

Tent only. Condensation is a tent problem in a way it is not a tarp problem, because a tent restricts airflow around a body giving off moisture all night: see tent condensation. Inner first designs soak the inner while you get the fly over them, a tent needs a tent shaped patch of flat ground, and poles break.

Try it before you commit#

Three checks at home separate the people who enjoy these systems from those who buy twice.

1. Pitch the tarp in the dark, in gloves, with one headlamp. Time it, then repeat with the ridge 30 cm lower and measure the covered width. Under about 1.8 m and your sleeping bag will touch wet fabric.
2. Hang the hammock and measure the angle. A phone inclinometer laid against the strap reads suspension angle directly. Aim for about 30 degrees, then lie in it diagonally for twenty minutes and see whether calf ridge or shoulder squeeze appear.
3. Sleep out at 12 to 15 degrees C in a hammock with no underquilt. The most informative night in hammock camping. The cold arrives underneath long before anywhere else, and after that the underquilt argument needs no explanation.

Common mistakes#

Buying a tarp with no bug bivy for a midge site. The tarp is not the problem, the missing 200 g of mesh is.

Substituting a pad for an underquilt below 18 degrees C. It half works on a mild night and fails at the shoulders and hips when it is genuinely cold.

Comparing fabric weights instead of system weights. A 300 g tarp needing 120 g of line, 90 g of stakes and a 280 g bivy is a 790 g shelter.

Hanging a hammock tight. A flat hang looks tidy, triples strap tension and gives the worst lie available.

Choosing on the trip you imagine rather than the trip you take. Score the terrain you actually walk in. If the answer is a tent, how to choose a tent picks the thread up there.

Frequently asked questions#

Is a tarp warm enough for cold weather camping?#

A tarp does not insulate, so warmth comes from the sleeping bag and pad. What it does is block radiative loss to a clear sky and cut wind, which together matter on a still, frosty night. In dry cold a tarp with a bivy is a serious system. In wet cold near freezing it is far less forgiving than a tent.

How cold can you camp in a hammock without an underquilt?#

Roughly 18 degrees C is the practical floor, and plenty of people feel it above that. The underside loses heat to moving air across one thin fabric layer, and anything you lie on is compressed flat. Below that, you need insulation hung outside the hammock where body weight cannot reach it.

How far apart should hammock trees be?#

Roughly 3.5 to 6 metres for a standard hammock. Closer than that steepens the suspension angle, which raises strap tension sharply and stops the fabric developing the sag you need to lie diagonally. Much further apart and you carry extra strap and lose usable height.

Does a bivy bag add much warmth?#

About 1 to 2 degrees C, from blocking wind and trapping a thin layer of still air rather than from insulation. Treat it as a windproof outer layer for a sleeping bag that also keeps splash and drips off. It traps moisture too, so breathability matters more than the temperature claim on the packaging.

Is a tent really more storm resistant than a tarp?#

Yes, and not because of the fabric. A tent holds a shape under pole tension that resists load from several directions at once, and its floor stops wind driving underneath. A tarp is a sail on two or three attachment points, depending on a pitch chosen for a wind direction that may change overnight.

Can two people share one tarp?#

Comfortably, which is a real advantage over hammocks. A tarp of about 3 by 3 m pitched as an A frame covers two sleepers side by side, and that single tarp splits between two packs. Two hammock campers need two complete systems, so per person weight does not improve with group size.

Do hammocks damage trees?#

Narrow cord does, by cutting through bark and the living tissue beneath, especially at sites used repeatedly. Wide webbing spreads the load over enough bark to avoid that, which is why many land managers require it. Use live, healthy trees of reasonable trunk diameter and avoid anything with dead limbs overhead.