Hammock Underquilt with Clew Suspension
ThermaClew is a hammock underquilt designed to provide stable bottom insulation for gathered-end hammocks.
Sleeping pads can be used in a hammock, but they sit inside the curved fabric and may shift during the night. In colder or humid conditions, condensation can also accumulate between the pad and hammock body.
An underquilt suspends externally beneath the hammock, maintaining continuous insulation without affecting internal space or movement.
Insulation here is structural.
Clew Suspension System
ThermaClew uses a dedicated Clew Suspension system that distributes tension evenly across the entire underquilt.
- Even contact along full hammock length
- Reduced risk of cold spots
- Automatic centering under load
- Stable positioning throughout the night
The suspension simplifies setup and minimizes adjustment errors common with traditional shock cord systems.
If using a non-Need For Trees hammock, please indicate hammock length in your order notes.
Why Clew Suspension Is Different
Most underquilts use perimeter shock cord suspension. Tension is adjusted at the ends and along the edges, and fine-tuning is often required after lying down.
Clew Suspension distributes load through multiple connection points along the length of the underquilt. When weight is applied in the hammock, the system self-balances and maintains even contact.
- Less edge gap risk
- More predictable alignment
- Reduced need for repeated adjustment
- Stable positioning during movement
The goal is not complexity — it is consistency.
Technical Specifications
- Suspension: Clew multi-point tension system
- Insulation: Climashield® APEX (100 / 133 / 167 / 200)
- Outer fabric: 20D Nylon
- Inner fabric: 10D Nylon
- Dimensions: 200 × 130 cm
- Total weight: 550–750 g (depending on insulation option)
- Packed volume: approx. 2.1–5.85 L (depending on insulation option)
Climashield® APEX Insulation
ThermaClew uses continuous-filament Climashield® APEX synthetic insulation.
- Maintains loft even when damp
- Machine washable
- No clumping or migration
- Resistant to moisture and mold
- Stable performance after repeated compression
Unlike short-staple synthetic fills, APEX uses continuous filament construction. This reduces insulation shifting and improves long-term durability.
Synthetic insulation offers predictable performance in humid and variable European conditions.
Temperature Ratings
Temperature perception varies between individuals. Values below reflect practical hammock use under typical outdoor conditions.
| APEX Weight | Comfort | Lower Comfort Limit |
|---|---|---|
| APEX 100 | 12 °C | 9 °C |
| APEX 133 | 7 °C | 5 °C |
| APEX 167 | 0 °C | -2 °C |
| APEX 200 | -3 °C | -5 °C |
Weight & Packed Volume
| APEX Weight | Total Weight | Packed Volume |
|---|---|---|
| APEX 100 | 550 g | 3 L |
| APEX 133 | 610 g | 3.56 L |
| APEX 167 | 670 g | 4.5 L |
| APEX 200 | 750 g | 5.6 L |
Layering Options
Underquilts can be layered for extended cold-weather use. For example, APEX 100 combined with APEX 200 increases total insulation.
Thicker custom versions (APEX 267, APEX 300 and others) are available upon request.
Compatibility
Designed for gathered-end hammocks, including all 360 cm (12 ft) Need For Trees models.
Length adjustments for other hammock sizes are available on request.
Frequently Asked Questions
Can I use a sleeping pad instead of an underquilt?
Yes. A sleeping pad can provide insulation inside a hammock.
However, pads may shift during the night, create side gaps in the curved fabric, and can reduce natural movement. In colder or humid conditions, moisture may also accumulate between the pad and hammock body.
An underquilt suspends externally beneath the hammock, maintaining consistent coverage without affecting internal comfort.
Is an underquilt really necessary?
In warm tropical nights, additional insulation may not be required. In most temperate conditions, heat loss from beneath the hammock occurs quickly without insulation.
What works best for 3-season use?
For typical European three-season conditions, APEX 167 works well for warm sleepers. Colder sleepers often prefer APEX 200 for added margin.
Should the underquilt be warmer than the top quilt?
In many setups, slightly warmer bottom insulation improves overall balance. Cold air circulates beneath the hammock, so under-insulating the bottom is a common mistake.
Regular vs Asym underquilt – which should I choose?
Regular underquilts are more forgiving and allow changing lay direction. They are recommended for beginners and general use.
Asym versions reduce weight and bulk by insulating only the diagonal lay zone. They are lighter but require consistent sleeping position.
Is 200 cm length enough? Can you make 220 cm?
For most users, 200 cm provides full coverage when properly positioned. Taller users or those wanting additional coverage can request extended length versions.
Can I wash Climashield® APEX?
Yes. APEX insulation is machine washable and does not require special detergents. It maintains loft without clumping.
Will APEX 200 be too bulky?
APEX 200 provides increased warmth at the cost of additional packed volume. For colder sleepers or near-freezing use, the added bulk is typically justified.
Esse Woods (verified owner) –
If this would have been invented a few hundred years ago, no one would ever had invented the regular bed.
This is what takes hammocking from a good idea to actually an amazing experience.
mario –
i bought the gheed single layer hammock, because i use it mostly in parks and siestas on hiking tours. i sleep in it only once in a while, so there was no need for the integrated mosquito-net of the gilis.
i really love the hammock! it’s lightweight and super small when packed, and the double-end-opening stuffsack is neat and handy. the 40d Ripstop is just right in terms of flexibility. the 3,50 m length is really comfortable for someone like me – 1,87 cm tall and coming from 3,00 m or smaller hammocks.
the thermaclew is lightweight, small when packed and seems to be perfectly warm so far. but i have to test it in colder seasons to really judge it. my only concern is, that the clew has a tendency to tangle up, when stuffed in the sack. i solved this issue by using small adjustable loops to bind the strings together – that seems to work for know.
other than the underquilts i tested before, you barely notice it, when laying in the hammock. It fits well under the hammock and doesn’t push you to the middle.
personally i prefer to know, that the working conditions are fair and non-exploitative and i like to support a small, european manufacture…
… especially when it’s so customer-friendly and offers such good quality!
Johannes –
I got the ThermaClew Summer last week and have only slept in it for a couple of nights. Build quality and materials are very good. Although it is designed for use with original NFT hammocks, I’m currently using it with a Simply Light Designs “Trail Lair”. As the hammock is equipped with clips/hooks for an underquilt, it is possible to just use the outermost shock cords of the UQ clew suspension in these clips. The UQ is kept in place perfectly, I have not experienced any cold spots so far. I plan on ordering a Gilis hammock as a more lightweight alternative to my Trail Lair as well as another tarp in the near future. After all, one can never have too many hammocks, and I’m very happy to have found an excellent source for handmade hammock equipment in Europe.
Leve (verified owner) –
It takes just 10 seconds to attach and always fits perfectly. Honestly, it doesn’t get any better than this
Sofia (verified owner) –
Really nice uq! It was light and felt fluffy to the touch. Easy to put up and fold together. The compression bag was amazing; made the quilt really small! I have only tried it in -5° celsius and needed an pad in the hammock to make it perfect but looking forward to try it in the “right” temperature for the qulits recommendation (winter). Good communication from the seller as well!
Felix (verified owner) –
I got the summer version and a modified winter version, and im super happy with them! My old underquilt had problems with it sliding to the side below me during the night, but these ones have added “hooks” that makes them sit in place perfectly. If you need an underquilt then you wont be disappointed with these! Them being very light weight is also great, and makes them a lot cheaper compared to similar underquilts from other sites. They are also very easy and quick to set up compared to my old underquilt.
10/10!