Ultralight Alpine/Four-Season Tent
SlingFin Hotbox
$650, 3 lbs. 9 oz.
slingfin.com
Through three cold December nights camped at over 8,000 feet in Idaho’s Boulder Mountains, snow fell hard enough that I had to dig this tent out a few times. All that cold, white smoke was great for two reasons: the backcountry skiing my kids and I did—and testing the Hotbox, SlingFin’s answer to the challenge of creating a lightweight tent built for alpine climbing and other four-season adventures.
The HotBox represents SlingFin’s modern take on the classic wedge tent for alpine climbing—with some stylizing of a design that’s seen little change in recent years, designing it in ways that will appeal to other four-season backcountry travelers and backpackers who push the limits of many three-season tents.
Not surprisingly, from a brand that has been reimagining what backcountry shelters do and how they do it (see other SlingFin tent reviews at this blog), the freestanding, single-door, double-wall Hotbox is not your father’s backpacking or mountaineering/four-season tent. Three features most distinguish the Hotbox from similar tents:
- The WebTruss, a pair of detachable, crossing sleeves that the two poles slide into, adding little weight while substantially boosting the tent’s stability in strong wind.
- Gear storage on both sides of the tent, accessed from inside, rather than a vestibule outside the door.
- Its double-wall design, with an inner tent and a rainfly, common in three-season tents but rarely seen in lightweight, mountaineering/four-season tents designed for very small campsites high up mountains.
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The HotBox’s WebTruss conveys the benefits of both the structural strength of pole sleeves plus the ease of pitching a tent with clips. The WebTruss creates a high strength-to-weight ratio by distributing wind force along the length of the tent’s two DAC NFL 9.3mm poles, to eliminate poles flexing at clip points in wind; adjustable black webbings at the four WebTruss pole openings can be tensioned for added strength (and must be loosened to pitch the tent). This design improves on traditional pole sleeves by eliminating the problem of sleeves being sewn on a diagonal to the fabric’s weave, which allows fabric to stretch and poles to flex more in wind—and potentially break.
The shortcoming of poles sleeves has always been sliding the poles through them—particularly complicated when wind keeps treating the tent like a kite. But because the WebTruss is detachable via side release buckles, you can insert the poles into it and tension the ends before attaching it to the tent, while it lacks much surface area for the wind to lift—meaning you won’t snap a pole that’s partway through a sleeve and flapping in wind. Yes, this is time-consuming, but so is pitching any tent in wind. And the last thing you need is a broken pole. The WebTruss also has O-rings on top that can be attached to toggles on the underside of the rainfly, creating an integrated setup that keeps the two attached while packed up for faster pitching in camp.
Characteristic of SlingFin tents, one set of pre-installed internal guylines and the capability of adding more also help boost structural strength.
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The gear storage consists of protected space under full-length snow flaps on both sides of the tent, accessed via round, drawstring vents inside that open wide enough to pass a backpack through; they resemble smaller versions of vestibules on two-door tents, but with greater versatility. The flaps can be toggled up to the inside of the rainfly when not in use, pulled out and staked using the adjustable stake loop, folded under the tent, or toggled to the O-ring at the top of the tub floor sidewall (requiring no stakes) to provide a dry platform for gear.
These door-less storage areas never expose the boots, packs, and other gear inside them to the weather whenever you enter or exit the tent; and that gear isn’t an obstacle in your doorway. Those side vents can close up completely to keep insects outside in warm temps, but that’s not the use this tent is primarily made for. Most critically for climbers, this gear storage provides storage that’s generally missing from that category of shelters—and can be reeled in when a ledge or small tent site lacks space for them.
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You might even cook in them—though space is limited, and with the caveat that, as when cooking in a standard vestibule in stormy weather, you must ensure there’s good ventilation to prevent the slow, undetectable killer of carbon monoxide buildup. That’s easier to do when there’s an exterior/rainfly door with a two-way zipper that can be opened slightly from the bottom. With the Hotbox, you might have to repeatedly clear fresh snowfall that could pile up around the tent’s perimeter and impede ground-level air flow.
The double-wall design unquestionably provides significantly better ventilation than single-wall tents, which chronically suffer from condensation buildup on the inside walls due to inadequate ventilation—especially in sub-freezing temperatures, the very conditions for which the Hotbox and similar tents are intended. Live in a single-wall shelter for multiple nights below freezing and it’s very hard—almost impossible—to prevent so much condensation freezing to your ceiling and walls that it begins snowing on you, your bag, and everything inside each time someone brushes a wall. With just one door on the Hotbox and other alpine wedge tents—eliminating the cross-ventilation you get in a two-door tent—the double-wall setup becomes even more critical.
Besides the benefit of double walls and the air movement enabled when the side vents accessing the gear storage are open, a drawstring ceiling vent at the foot end, which can be used with or without mesh depending on bugs, and a zippered solid panel over a mesh window (for buggy conditions) in the upper portion of the door create end-to-end air flow—thus, interior can get air flow from four directions, lending the Hotbox unusually good ventilation for a single-door tent. On three consecutive, calm nights in the single digits to teens Fahrenheit—conditions notorious for frosting a tent’s interior—negligible amounts of condensation accumulated on the Hotbox’s interior walls, not enough to start snowing on my bag or get anything inside the tent wet.
While I camped in forest rather than on a narrow ledge on a mountain ledge, it’s clear with the Hotbox pitched that it covers a relatively small footprint, with 26.8 square feet of floor space, the interior 82 inches long and a generous 52 inches wide at the head, tapering to 42 inches at the foot. While that’s snug living for two people, two standard air mattresses (20×72 inches) fit side by side with space to spare and the 41-inch peak height is good for a tent in this category and weight class. Plus, eight pockets provide abundant organization, helping to keep stuff off the limited floor and easier to find.
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Pitching the Hotbox isn’t very intuitive, but I found that one practice session in my back yard, using this helpful video from SlingFin, enabled me to erect it—by myself, atop deep snow in the backcountry—about as quickly as I pitch many freestanding tents. The Hotbox can be pitched in four different configurations.
- The standard setup of clipping the tent canopy directly to the poles, adequate in most conditions.
- A high-wind setup that entails running the poles through the WebTruss to boost stability and wind resistance and reduce the chance of breaking a pole while pitching the tent.
- An integrated setup that leaves the tent body attached to the rainfly when packing the tent away, for faster setup that also keeps the tent interior dry when pitching in inclement weather.
- Using the 12 DAC twist clips that come with the Hotbox instead of the WebTruss, for reducing tent weight a bit when using the Hotbox in mild weather—making it a legitimate all-season tent.
A major drawback of any alpine tent that lacks a vestibule protecting the door is that snow and rain can inevitably enter the tent when you come and go. That’s one price of a shelter that’s lightweight and fits on a very small site.
The breathable, 15-denier nylon ripstop fabric used in the tent walls blocks wind, spindrift, dust, and sand. The 20-denier, sil/sil nylon rainfly will not sag as much as sil/PU nylon, never hydrolyze, and is extremely resistant to mold and mildew while striking a balance between weight and durability. The rainfly’s 14 external guypoints—yes, 14—seem to prepare the Hotbox for a category 1 hurricane. I used fewer than half of those guypoints through the snowstorm and had no trouble with wind or snow affecting the tent. As it dumped outside, the weather was hardly noticeable in the dry interior.
Like many mountaineering/four-season tents, the Hotbox comes with DAC J-stakes (14 of them), which are strong but intended for pounding into earth, not into snow, for which they’re much too narrow; I used a few as deadmen for staking but that’s tricky and it’s easy to lose skinny little stakes in snow. For camping on snow, you’ll need true snow stakes or other things you can use as deadmen (like stuff sacks filled with snow or skis, provided you’re not basecamping and using your skis during the day).
The packed size of 6×19 inches compares with many three-season tents of similar weight but built for milder weather conditions.
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SlingFin Hotbox
The Verdict
For climbers and other four-season adventurers looking for a lightweight, strong, and compact shelter versatile enough for all seasons, the SlingFin Hotbox offers a new take on a classic wedge tent, with good ventilation, gear storage, and multiple pitching configurations.
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—Michael Lanza