Tag Archives: slackraft

Tested: Supai Flatwater Canyon II packraft review

Full trip report here (mostly walking)
June 2015: Supai Matkat review

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At a verified 670g (23.6oz) including an added grab line, Supai Adventure Gear’s Flatwater Canyon II ($300) must be among the world’s lightest and most compact boats. 
Before a winter storm blew our plan off the map, the trip we’d lined up in northwest Scotland was ideal for the Flatwater: short crossings saving lengthy overland detours or risky deep wading, but no extended or exposed paddling.

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Fabrication
Examining the deflated raft, it became clear it was composed of just four pieces of flat material: the top and bottom ‘rings’ which define the hull shape, an inner hull wall joining the top to bottom, and the floor fixed under the completed ring. You could almost make one yourself.

No fabric details on SAG’s website, but the Packraft Store states: ’75 denier polyester with single, innerside urethane coating’. This whole denier thing can be a bit misleading, the raft fabric looks and feels similar in thickness to my MSR Dromlite water bags (right) made from 200 denier, PU-coated Cordura (nylon?), but the Flatwater polyester has what looks like a reassuring ripstop weave (visible below left). And as we know from our studies in IK hull fabrics, polyester stretches less than nylon and so is more suited to inflatable boat applications than compact water storage.
Where the seams overlap on the outside edge they’ve included seven reinforced tabs (above left) to use as attachment points (a weak point on my non-ripstop Dromlites, even with an eyelet). The floor is made of the same weight fabric and shows what look like ‘spot welds’ along the inch-wide seam (middle).

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That’s it, apart from a big threaded inflation port onto which screws a white cap fitted with a 18-inch hose topped with a blue twist-lock valve (left). You blow the boat up by mouth (took me about 45 breaths) then top up to operating pressure with the twist lock, like on an Alpacka. But unlike a pre-Boston Alpacka, the long hose means you’re able to further top-up from the water where inflatable boats initially sag as they cool. Plus you could potentially manage a slow leak the same way.

Sevylor TrailBot

The hull form tapers and narrows towards the bow to resemble a blunt wedge, similar to old Sevylor Trail Boat (right). Like all packrafts and even slackrafts, the added buoyancy (tube diameter) in the stern counteracts the mass of the paddler’s weight. There’s no seat and a new boat comes with a repair kit with full repair instructions on the SAG website.

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Some of my measurements (checked several times and now confirmed by the Packrafting Store) vary greatly from those still posted on the SAG website many years later in 2020 and which had their Canyon over 10% bigger, inside and out.
Even if they’re factoring in ‘paddler squidge’ making more room inside by pushing on the hull, that won’t make the boat seven inches longer.

As for buoyancy, SAG originally quoted ‘250lb’ (now a more realistic 200lb or 90kg). Robin briefly paddled the raft with his pack which we thought added up to about 100kg. That felt like the limit once a light breeze came up the valley, and required gentle paddling to avoid too much cyclic bobbing and possible swamping.

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With the weight; the Store states 633g, SAG quote 24oz (680g). As mentioned, with a grab line and traces of dirt, our boat comes in at 670g on the IK&P calibrated kitchen scales (left). I won’t quibble over 40 grams; to be able to paddle across a loch in a boat weighing less than my trousers is quite something.

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On the water
The air was calm but temperatures were close to freezing as we set off to cross the eastern narrows on Loch Lurgainn below Stac Pollaidh mountain.
We’d originally planned to come over in the other direction from the Culnacraig shore, but the storm which went on to wreak havoc across Britain nixed that plan (story here). So today we were just taking a 10-mile day trip with a short paddle, from Stac car park southwest back to Altandu.

‘Fragile and small’ had been Robin’s first impressions after Sven from the Packraft Store in Germany sent us the raft to evaluate. Robin had recently upgraded to a couple of Gumotex Twist IKs so may not have been impressed by the Supai’s thin fabric. I had more faith in that, but as for the size, I too anticipated that SAG had cut it a bit fine with the Flatwater II, even if it lived up to their motto: ‘where every ounce counts’.

Down on the loch shore, even with a helpful breeze to fill my Yak’s bag, inflation time for both boats was actually the same, although by the end of it Robin was staggering around a bit. As Tim Evans found on his trip, other inflator bags can be adapted to avoid passing out.

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Now, laid alongside my Alpacka Yak (same width but 66cm or over two feet longer), to me the Flatwater’s proportions rather too closely resembled a slackraft I skinned from a Sevylor pool toy a year or two back. I knew that with my weight of about 100kg in gear, I’d be pushing this boat’s limit. Without a drysuit I didn’t want to risk it.

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It took some prodding to get packrafting newb Robin (80kg + clothes) in the Supai and I’m not sure I blame him. A sudden move could see the stern dip down and douse the butt. After fitting his closed cell mat to keep warm and protect the thin floor, he set off for a quick spin and soon realised there wasn’t so much to worry about. Paddling gingerly with his home-made paddle (a broom stick, two sawn-down buckets and zip ties) he did a few loops while learning to control the annoying yawing you get with short packrafts and slackrafts, as well as managing the less welcome bobbing which might amplify into a back-end pour over. Yawing keeps the speed down which may be just as well. Start paddling too fast and the bow will rise with a corresponding drop at the stern when slowing down, again risking a pour over in wavy conditions.

Having established he wasn’t going to sink with all hands, I lowered Robin’s 10-kg pack onto his legs then hopped into my Yak. The pack’s added frontal weight should minimise the Supai’s yawing – at least that’s the effect on my Yak. But it’s well known that first time in a new packraft, especially a short one like the Flatwater, paddling efficiently is an acquired knack. Our extra chilly scenario (not helped by his experimental B&Q paddle) meant that Robin couldn’t really relax or bomb around in the Supai. (I tried his B&Q but soon sent it back as it brought in unwanted splash all over my boat). A gust rolled up the valley, rippling the loch’s surface, adding further to the feeling of anxiety in the Supai. From my PoV it looked like the stern was more than half sunk at times – and half sunk on a round tube makes pour-overs all the easier.
I skimmed over to the other side and got out to get some long shots and was reminded yet again what a great boat my Yak is. No worries about getting in clumsily, sudden winds or carrying Robin’s pack. Sat here a day earlier when a gale was ripping through at an average of 35mph and gusting to twice that, it may have been a different story, but my long-bodied, yaw-suppressing, high-sided, tough hulled Yak inspires confidence, even without the spray skirt.

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The price you pay is weight and bulk. Ready to paddle, at 3.1kg with seats, heel pad, pack attach and lead,plus other straps and some mini krabs, my boat is 4.5 times heavier than the Supai as tested, and even more bulky when you add in the blow bag, skirt and repair kit: the red bag shown right.

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Robin slowly waddled over to the south edge of the loch and got out with care before pulling the plug and rolling it up. As on any inflatable, the floor is vulnerable and we discussed ways of getting round this. One problem is the Supai’s floor glues to the hull ring above the lowest points in the hull tubes which means the undersides of the hull are actually lower than the floor (until you sit in it on the water). Using a thicker floor panel won’t eliminate all possible wear. Robin is a versatile home-fabricator (as his B&Q paddle proves) and we decided the least invasive way of protecting the entire underside – hull and floor – would be to string a sheet of whatever you like from the peripheral half-inch hull seam (the seven reinforced tabs not being quite enough to do the job). No messy, irreversible, crease-inducing gluing required, just a line of holes along the seam plus a drawstring. Pre-emptive protection is something I’ve done to my Alpackas’ ballistic nylon floor and although it won’t look too neat, a floor sheet would enhance the less robust Supai’s undercarriage, despite a weight penalty.

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Our conclusion
He may have got used to it over time, but the Supai felt too skimpy for 80-kilo Robin. Ill-dressed on the day and over-fed in general, I didn’t even try to get in. Build quality is great and the fabric I could live with; it’s much better than slackraft PVC and the extra care needed in handling is well worth the weight saving over an Alpacka. Factoring in experience, company (support), weather conditions and operator weight, the Supai felt right on the limit. Initially you’re reluctant to paddle normally for fear of swamping which could turn exponential. Alongside a Yak it’s a pretty slow too, although I don’t think that’s a flaw. My Yak is slower than my IK which in turn is slower than … As long as it makes progress, a boat is as fast as it is.


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Alpacka’s Scout might be a fairer comparison with the Flatwater II. According to Alpacka stats it weighs 1450g, is 4.5cm narrower, 2cm shorter inside and 26cm longer overall, while costing at least $200 more in the US. That still puts the Supai well in the ballpark on weight and cost. Anfibio’s Alpha XC is another which I’ve actually tried.
Although it looks to have been designed for the canyon lands of southwest USA, for the lighter paddler the Supai could a great packraft for less predictable Scottish conditions involving short, flatwater crossings. The negligible weight really opens out the options and means you don’t have to get too fanatical about the rest of your gear which can translate into greater comfort.

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I knew this even before I saw the boat, but what I’d love to see is a Flatwater XXL more closely matching my Yak’s (or my) size. I’d happily trade the extra 8cm of width the Supai has at the hips for fatter and higher tubes all round, plus another 10cm added to interior length. It’s hard to think that would add up to much more than a kilo overall, but would reward the portlier or overnight-equipped paddler with a more versatile boat able to deal with dodgier conditions. Let’s hope this is part of Supai’s game plan.
* SAG later released the Matkat. Not exactly what I was thinking but we tried that too.

Photos also by Tim Evans who writes:

I got interested in packable boats as I love both walking and being on the water. My first major trip was in an Alpacka Yak from Whistler to Vancouver. I hiked for 2 days, paddled the Cheakamus River for a day (with some easy whitewater), then paddled 24 miles of ocean inlet back to Vancouver. This trip was only possible because of the packraft. Then I bought a Supai and did 35km through a lake system north of Vancouver that included a number of portages. I saw a pair with a canoe which they pushed on a trolley through the portages with 200lbs of gear. It took them hours to go a few km. I did the 4-day trip with 16lbs of gear including food, just to see if it could be done (it can). I could have jogged through the portages with my little boat tucked under my arm. The Supai was a light as it gets, but SLOW for any sort of distance.

Slackrafting to Clashnessie

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As we left one car near Stoer, out to sea a stampede of white horses were galloping in towards the Bay of Clachtoll. It looked like a late 90s Guinness commercial out there. We didn’t want to be kayaking in that, no sirree.
So instead Jon and I swapped craft and set out to follow a string of lochs which filled a fault line marked on the maps as ‘Gleannan Salach‘ (above). It ran west from Loch Assynt to the sea, across a lochan-speckled headland tipped by the Point of Stoer. To the south Enard Bay (which I kayaked a few weeks ago) to the north Eddrachillis Bay; all ringed by the cute Drumbeg road. I’d clocked this as a viable packrafting ‘line’ some time ago and today was the day.

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It was only about seven miles, road to road. But from the look of the map and knowing the terrain around here, I expected the walking stages to be sodden, gruelling bogs or chest-high fernfests. We’d found as much on Horse Island the previous day.
Jon was debuting his skinned dinghy (more on that idea here), last seen here during a bitterly fought offshore jousting tournament we’d held off Achnahaird Bay a year or two ago. I’d cut my own slackraft down a while back but found with my weight, the freeboard was a limited and the slightest wave would swamp it. Luckily that was all the excuse I needed to be allowed to use my proper packraft.

It was going to be a day of blustery winds and heavy showers so appropriately dressed, we parked up at the Leitir Easaidh end near Loch Assynt and put in at a shelter by a boat ramp. On inflation, Jon’s slackie looked ridiculously small, an impression that worsened once he actually got on it. And on the water the situation deteriorated still further; that thing pulled half the speed of the ‘packa, yawing left and right like some demented dashboard ornament in need of a good slap.

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A relative novice to slacking, it’s possible Jon was paddling as if he was in his 17-foot sea kayak which has a length/width ratio of over 8:1. On his slackie it was less than 2:1. Long, powerful strokes merely flip the bow left to right, as I found when I first tried my original Alpacka Llama. It takes a bit of a knack to limit yawing, although the newer ‘fastback’ tailed Alpackas like my yellow Yak, greatly minimised that. Previous slacking expeditions in France and the Kimberley has been with unskinned, full-width slackboats which attained some two thirds of an Alpacka’s peak velocity, once you’ve divided the surface tension by Ω x π. It brought up the troubling possibility: was removing the outer hull to gain slimness at a slight loss of buoyancy not as efficacious as previously thought?

By the time we got to the far end of Loch Leitir Easaidh we’d already been rained on and blown about twice. Faced with a steep climb through knotted woodland and thick bracken, we rolled ’em up and go stuck in. Soon we were at the pass which overlooked the next lochan and by the time we were back at the pumps that one mile had taken an hour.

We estimated the rest of the crossing would probably be at the same slug-like pace, so to get home before Christmas, I towed the slackraft. Jon paddled too of course, the tow line constraining his rampant yawing as we clung to the leeward south shore. Alone on windless flat water, my packraft can sit on 3 mph. Out of the wind our packboat convoy managed about two which was good enough. At the far end a short portage dropped us a few feet down to Loch Three, and at the end of that one a deer fence stretched across the small weir before Lochan a Ghleannein Shalaich, loch #4.

At this point the map showed the flow funnelled into a narrow gorge which could mean an awkward climb to get round. We’d decided if it took ages to get to the gorge we’d turn back, but lined up we were averaging a little over our target 1 mph so the mission rolled on. Better still, an easily walkable route ran alongside the stream through the gorge (above), then opened out to an agreeably grassy basin that didn’t involve thrashing through chest-high bracken or sinking into unset peat. Unusually, walking here proved to be faster than paddling.

That stage gained us some time, but back on the water we took a few steps back. The southwesterly gale sweeping across Loch na Loinne must have been accelerating round Cnoc an Dubharlainn, at 223-metres, the highest hill in the ‘Salach’. A couple of islands provided inadequate protection from 35-mph sidewinds which hammered down on the rafts. We both dug hard on the right and barely the left across the exposed bays, managing between 1.5- and 2 mph, though it sure didn’t feel like it. The shortest rest saw us skitting across the choppy waters to the northeast bank.

Out of the wind it’s another world. By a wooded cliff we glided past the controted, banded Lewisian gneiss that makes up the bedrock of this waterlogged region. Said to be three billion years old, the Salach badlands has had its capping of oxblood coloured Torridon sandstone scrapped away, right down to the raw bones of the primeval gneiss. At the far end they’d built up a rubble and mat barrage which diverted the outflow through a pipe. Purpose unclear, but after the effort of getting here, I suggested we unline for the next little loch before one more portage brought us to Loch Poll, the last and biggest loch.

Untethered, the Alpacka Yak skimmed across the lochan like a spun stone. Jon was not so far behind and we both squeezed under a fence and along a channel before we ground out on mossy boulders and took to the banks. The whole traverse seems to follow an ancient wall and a newer fence, and as the winds strengthened we popped through a lonely gate and over a pass clinging to our inflated boats. Down on the far side, again we managed to paddle a meandering, reedy stream until a small waterfall barred access to Poll. Raining, blowing and cold, it was a good time to cram in the last of our squashed snacks for the final haul.

Slackerman, where you gonna run to?
And a haul it was. The winds and rain intensified to the point where we decided, that even at our glacial pace, better to take a longer route around Poll’s southern edge. Flat against the wind at times, from the look of the passing shore, our lined-up flotilla crept along at barely a mile an hour. In fact a ’10’ marked on the OS map has obscured a couple of handy islands that would have made crossing Loch Poll’s 300-metre wide ‘neck’ not so exposed, though that route may have put us against the biggest fetch and rebounding winds.

We curved round the loch’s southern shore to gain a brief spell of backwind and then with more hacking, arrived at the take-out bay at 7pm, six hours out of Leitir Easaidh. It was a ten-minute walk to the road and the car, somewhere within a mile. Half an hour later, where was the car? Not in Strathcoy, not in Imirfada. Had we turned the right way off the Salach? At Clashnessie Bay I was forced into that ultimate humiliation: looking at the map. Oh dear. I got Clachtoll near Stoer mixed up with Clashnessie, also near Stoer; I had assumed the Gàidhlig Buidheann-stiùiridh doi Teanga (Gaelic Language Directorate) had changed the name. Another three miles march it was then, into a headwind so strong we couldn’t hear each other talking. Ardmair near Ullapool recorded 48 mph around that time.

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So, has the cut-down slack rafting myth been finally punctured with a blunt wooden spoon? I knew they were slow but Jon’s boat seemed worse. Still, my Amigo IK is the same alongside Jon’s Scorpio sea kayak – not as fast – so you’re as fast as you are.
I still think for a hill trekker carrying a slackraft that’s no slower than a Supai, lighter than my Alpacka and a fraction of the price, still enables water-inclusive routes across the well-suited northwestern highlands. Longer crossings may take a while but you paddle. That’s what you do. Splish follows splosh follows splish follows splosh. Good things come to those who wait.

Slackraft Sea Trials

Slackrafts main page

Chopping down my Sevy pooltoy into a slackraft lost too much buoyancy to take my gross weight, but it works fine for the Mrs who’s about half my weight. So on a very calm, sunny morning – realistically, it’s inshore limits – we took the Sevy out to the Bay for a swim. I’d glued on an extra outer covering of ballistic nylon to save the vulnerable floor, as we had planned to take it down the Escalante river in Utah a couple months back, but it was way too hot for that when we got there and since then, as you may know, much of the US has been suffering a terrible drought.


As often, the first paddle in a short boat like this sees the operator yawing from left to right like a crowd watching a ping pong final. After a while, though the paddling technique adapts to reduce this effect, but even then the boat is still much slower than an Alpacka. This Slackie is only 28″ wide by 56″ long – 2:1 – (my Yak is 88″ x 36″; 2.44:1) and the Mrs found the best trim was sitting in the middle, even if this meant nothing to lean back on and was not sustainable. Next time out we’ll take a fishing buoy or something to lean against, although I do wonder if some sort of trailing skeg – a board sticking out the back rather than an under hull skeg like on an IK– might help subdue the yawing and so direct the effort in a straight line rather than zigzags.

My Alpacka skims along just like it always does; what a great boat it is. Annoyingly the backrest is leaking again from the twist valve base, even though it’s been glued up once. I find you do need that backrest to sit correctly in the boat, so another repair is due.
We dipped about, followed the river channel and out to sea and on to the rocks. As the tide turned we headed back up the river, against the flow the slackboat soon slowed to a near stop and it was faster led on its string through the shallows until a tailwind helped blow us back to our shoes, by now stranded some 200m from the water’s edge in just an hour.


A post-sea trail inspection showed that my carefully glued floor was coming away from the Sevy’s PVC hull like damp wallpaper; that may have explained why the boat got so slow coming back. The Evo Stik didn’t take to the hull at all, or if it did, seawater soon dissolved it. At the time I was trying to save on my nice Bostik 1782 which I used elsewhere on the slack boat with no problems. Anyway, it’s not worth wasting any more glue on this boat. And who knows, perhaps the ribbed floor which has been exposed again may help restore some tracking. We’ll see next time. We’ve half a mind to repeat last year’s fabulous Suilven triathlon, but this time in a boat each.

Skinning the Sevylor slackraft

See also:
Slackraft river trials
Slackraft sea trials

As promised, I’ve invested in a Sevylor Caravelle PVC dinghy. Cost: £34 delivered complete with pump, oars, repair kit, manual in ten languages and a box which is bound to come in useful one day. The heavy-duty Super Caravelle model, as modified by Narwhal, is out of stock in the UK until next summer, although an Intex Sea Hawk is the same thing and can be ‘skinned’ of its outer hull (as in the graphic, right) in the same way to make a lighter, narrower and nippier ‘PVC packraft’ – see bottom of the page. That’s the purpose of what is being done here, in case you’re wondering.

Pre-skinned and rolled up, the Sevy was about the size and weight of a proper Alpacka packraft, but awaft with that dizzying scent of PVC which takes you back to Mallorca in the late 1960s. Fully inflated, it’s too wide to take seriously, but it stayed like that long enough to enable the outer chamber to be surgically removed with a bread knife. Unfortunately, it’s on this outer chamber that the half-decent ‘high volume’ Boston valve is fitted – all the rest (2 floor chambers and the inner hull) get poxy, beach ball-style push-in valves which, in the latter case, take a while to inflate due to the pencil-thin aperture. Perhaps the Boston can be grafted onto the inner hull; what’s the worst that can happen? I’ll find out soon enough as it also took so long to deflate the remaining hull by squishing the push-in valve I decided to cut it out there and then and slap on the Boston valve from the trashed outer hull over the hole (above left). This was the first time I used MEK solvent to clean PVC. This stuff is pretty damn potent and ‘cleans’ the PVC a bit like paint stripper removes paint! Tellingly, it’s also known as polystyrene cement and has uses for welding too, so use it sparingly on PVC pool toys or they’ll dissolve before your eyes.

The squidgey little foot pump (right) is very light, but slow, especially when trying to get enough pressure into the main chamber for the slide-marker to move down and line up with the ‘A’ on the SevyScale™ (below left). This is a pressure guide so you don’t burst your new pool toy – easily done with thin, stretchy PVC and sharp words. But by chance the Sevy valve plug fits neatly onto the end of my K-Pump which is much quicker at inflating. The Alpacka air bag sort of screws into the Boston valve too, but you need a K-Pump to get max pressure.


Testing the newly glued on Boston valve, the boat was losing air, but it didn’t look like the glued-on valve was at fault. As it happens the bath was full so a check revealed a tiny, half mil hole near one of the seams underneath. I’m fairly sure I didn’t jab the boat with the knife while skinning it, so it must have come like that or my carpet is sharper than I think. Lesson: test all chambers in your cheap pool toy before running a coach and horses through the warranty by attacking it with a knife – that’s if you can be bothered to send it back instead of dab some glue on the hole, should it also be faulty.
The oars are mere fly swatters as previously noted. It’s possible they could be joined together into a packrafting paddle, but why bother; there are decent Werners and Aqua Bounds under the bed so the oars can join the scrapped outer hull at the local dump.

It has to be said, once skinned it’s 36″ (91cm) wide, 60″(152cm) long, and no more than 12″ high at the bow, so there doesn’t look to be a heap of buoyancy left over for the likes of bloated boaters like me, but the floor also holds air unlike an Alpacka so a spell on a river will reveal all. As mentioned, if it’s enough to stop me sinking, I may invest in gluing a spare sheet of tough nylon onto the base. It may add weight but will make the Caravette unstoppable; that’s unless a sharp-clawed bird lands on the deck or it gets splashed with MEK.

With half a dozen attachment points cannibalised from the outer hull and glued onto the stripped-down packboat with some Bostik 1782 (right), it now weighs 1550 grams; about half the weight of my current Alpacka Yak and about half the volume once rolled up. So compact, it could even make a flat-water towing platform for the Yak – for carrying a bike for example, as I’m not sure it would so easily fit on the bow, especially with camping gear.

River trials will follow shortly, or I may well head straight out to Rannoch Moor for an overnighter with Intex chum Jon who lives up there – see the vid above from last summer. He has also been inspired to skin his SeaHawk 1 bloat into a purposeful packslab. Might be good to take the Yak as a spare up there; if Loch Laidon freezes up round the edges the ice spikes might be too much for our pool toys.

Slackraft river trials
Slackraft sea trials