These days IK are mostly made from PVC, be it the hull or the bladders. Just three main IK brands still using old school synthetic rubber: Gumotex (CZ), Grabner (AT) and NRS (US). PVC gets recycled, is made everywhere and so is cheap off the roll and easy to heat weld. But is it only me who finds something unpleasantly ‘plasticy’ about PVC: the stiffness, the texture, the smell and maybe the eco-stigma.
The only PVC IK I’ve ever owned punctured on the slightest thorn and went on to do that with the next owner. And this was supposedly quality Mirasol PVC from Germany (to be fair, a mate with an older K40 had no puncture problems whatsoever). I can’t imagine any Gumotex or Grabner I’ve had ever doing that. That’s why I persevere with synthetic rubber IKs, even if I believe it’s becoming an expensive dinosaur fabric.
Synthetic rubber coatings like Nitrilon and EDPM are derived from the original DuPont hypalon. Boats must be entirely hand glued which adds to costs. But, in the same way nothing man-made has yet managed to beat the properties of leather for crashing fast motorbikes, compared to PVC, synthetic rubber remains more durable and more resistant to UV, lighter, more supple, easier to glue and easier fold compactly. After 15 years there was no noticeable deterioration in my Sunny, (below) other than a decade and a half of paddling wear and tear. A synthetic rubber IK will easily outlive a similar PVC IK.
Packrafts, meanwhile, are mostly made from TPU (as well as PVC), a different sort of polymer coating which has many of the benefits of synthetic rubber: odour-free, smooth texture, light, UV resistant, supple (crease-free), not environmentally toxic. But, like PVC, it too can be heat welded. Since Alpacka got the ball rolling, there are now loads of brands banging out TPU packrafts left, right and centre. In this time the fabric and seam technology have proved themselves to be as durable as PVC or rubber, and capable of running higher pressures. As someone on the internet observed: ‘Thermoplastic Polyurethane (TPU) is the link between rubber and plastic’. For inflatables TPU is clearly superior to PVC in all ways except price. “It has properties between the characteristics of plastic and rubber. So, it is flexible without plasticizers, and its flexibility does not affect the design or its strength and durability.” Link
In a way, my 3-metre MRS Nomad packayak (above) was as much a TPU kayak as a packraft. With just 2psi or so, it was able to hold its shape (or my centralised weight), but now costs nearly €1400 in the decked version. The only PU (same as TPU?) IK I know of is NRS’ discontinued Bandit series. It was made in China but still dropped, I presume due to cost reasons before they started making many more models with PVC.
Zelgear TPU IK
While researching the Zelgear Spark 450 preview I found a 2018 ZelGear catalog. It states their now discontinued 5.2m PVC Igla IK can be requested in TPU (or the similar and much stronger Vectran which Alpacka use for their top-of-the-range packrafts). There’s more here. The weight of this long boat: is said to be just 15kg. The cost? $2000 I was told.
You may wonder if relatively thin and flexible packraft TPU could support a 5-m IK? TPU coating is also said to be more elastic than PVC, but it can’t be any more elastic than rubber. And anyway, a stretch-free scrim (woven core) takes care of that; the coating is primarily for impermeability.
An IK needs to be a lot more rigid than a relatively short and squidgy packraft. A lot of that is down to the fabric as well as the psi. That’s one good thing about inflated PVC: it’s stiff. You’d think a TPY IK would require high pressures to support a long boat which would then require bombproof seams. But add a drop-stitch floor (left) in TPU to take the load and the tubed sides would be under less pressure, so to speak. This Zelgear blog post from 2018 mentions some “some technological issues are being resolved“. I’m told Zelgear are on it. Pictures below by Marcin S from a boat show in 2018.
With all these Asian-made TPU packrafts knocking about, some using locally sourced fabric whose quality – in my experience – is as good as the Alpacka stuff, the cost of TPU fabric may drop to a level matching the few ‘hypalon’ IKs still available.
A few years ago I predicted that full drop-stitch IKs would become the new thing. This has happened and has driven IK design and sales a long way forward . But, PVC aside, I’m still not convinced by the boxy profiles and packed bulk of FD-S IKs. Until FD-S forms can evolve (as the Itiwit X500 has shown), I think drop-stitch floors (D-SF) are certainly the way to go, if an IK is to stay undecked, unlike the X500.
There will always be a demand for cheap vinyl or PVC IKs but I predict the next big thing in high-end IKs will be TPU, including removable D-S floors in TPU. TPU is now well proven with packrafts and blends the heat-welding benefits of PVC with nearly all the better attributes of ‘hypalons’.
Since 2019 the Gumotex Thaya sits alongside the near-identical and 20% cheaper 4.1-m Solar 3 (aka: ‘Solar 2‘ or ‘Solar 019‘) on which it’s based, but with a drop-stitch (DS) floor to greatly improve rigidity. The Solar was not unlike my old Sunny, running just 3psi (0.2 bar) all round. As you can see on the left, that can get a bit saggy with a well-fed solo paddler. This was the first of Gumotex’s DS-floor boats, but a basic exercise in simply replacing a floor rather than trying anything more fancy like the Rushs of 2020.
Drop-stitch fabric now makes the complicated hand assembly of pressure-vulnerable I-beam floors (left) redundant. A DS floor is a flat panel with effectively 3-4 zillion ‘I-beams’ (see top of the page) all spreading the pressure load evenly to constrain the form into a plank shape, but at a much higher pressure than an I-beam floor can safely handle. In an IK, high pressure = a more rigid hull = better glide/less effort with barely any additional weight. The only drawback is that you need a more powerful high pressure barrel pump (above right). The old Bravo foot bellows won’t do anymore.
DS is normally PVC and made in China, but Gumotex have found a way to manufacture the threading and bonding a D/S floor with their durable, flexible and environmentally right-on Nitrilon rubber fabric. It can’t be that hard. The regular, normal-pressure 3psi sidetubes ought not need the higher pressures I ran on my adapted Seawave because the 7psi (0.5 bar) DS floor greatly aids rigidity (see action video below). Gumotex’s new tag line rubs it all in: ‘Made in EU[read: ‘not China’], made from rubber[read: ‘not PV … spit … C’].
The promo video below suggests something revolutionary, but combining DS with Nitrilon can’t be that much different from doing the same with PVC. It will certainly simplify or speed up assembly. One assumes drop-stitch floors supposedly don’t need a PRV necessary to protect I-beam floors from internal ruptures when they overheat in the hot sun. Some UK outlets where claiming the Thaya has a “Safety relief valve [PRV] in the bottom of the boat” but it’s probably just a copy and pasting error. I can’t see one in any pictures and have yet to see a DS panel with a PRV until the AE AirVolution came out in 2020. The assumption is they don’t need it if tey run a modest 7psi but some claim high-pressure DS floors won’t last as long as I-beams. Without a PRV, that may be true and much will depend on running the correct recommended pressure, the quality of manufacture/assembly and where possible, leaving the boat in the water on hot days so the large water-contact area keeps things cool.
One positive thing about I-beam floors is the parallel I-tubes (left) probably don’t hurt tracking (even without a skeg). They also enable the desirable curved hull profile of a boat rather than the flat floor of a barge (for the moment DS panels can only be flat or maybe with a slight curve).
Payload ratings seem to have settled at 230kg and the movable seats are also made from DS panels. Initially I thought why? For the backrest and footrest that makes sense but who wants to sit on DS seat base on a DS floor? Of course you don’t have to pump DS up to the max to get its flat form constraining benefits and it looks like valves are regular twist-locks so you’d couldn’t get more than a couple of psi in there. Footrests are the usual inflatable pillows, but possibly also DS. I’d replace them with a section of sawn-down plastic drainpipe so you get a solid block to brace against. It makes efficient paddling much easier.
I’ve never tried one, but I do wonder how a flat-floored DS IK might handle in windier, choppier conditions where an IK isn’t exactly a hydrofoil at the best of times. A flat, raft-like floor will be stable, sure, but it will roll and pitch about more. Also, according to the specs (left) at 89cm the Thaya is a disappointing 6 or 9cm (3.5″) wider than the all-tube Solar 3 (Actual verified width seems to be 34″ or 86cm). Great for family-friendly stability; not so good for solo paddling speed and efficiency. My Seawave is 2cm narrower than a Solar 3 and with the usual care getting in, stability is not an issue. Out at sea my Seawave will swamp long before I’m tipped out. But then again, the near-rigid floor may cancel out the drawbacks of the greater width. At 18kg the Thaya is heavier than a Solar 3.
For most recreational, flatwater users the Thaya ought to be a nice family boat, but then so is a Solar 3. The Thaya costs 20% more than the Solar 3 whose days may be numbered. One assumes this
As predicted here years ago, before long someone was going to find a way of making a decent inflatable kayak entirely from drop-stitch panels. Something a bit more sophisticated than the three-plank bathtub on the left. Right now there’s more interest than ever in what I call Full Drop-Stitch (FD-S) IKs because buyers view them as superior to a traditional round tubed IK. Certainly they’re miles better than just about any low-end PVC Sevylor or Intex, and don’t quite have the days-long drying issues of Shell & Bladder IKs, but prices are currently still high and there’s still something to be said for a good quality high-pressure tubed IK, or a ‘hybrid’ with a D-S floor and tubed sides.
What is Drop-stitch?
For the full story on drop-stitch (D-S) click this.
Short version: a dense mass of non-stretch ‘space yarn’ is magically stitched between two fabric sheets with thousands of stitches per square metre. The dimples you see on the panel surface are the space yarn under tension. Once the sheets are coated with PVC and sealed round the sides this makes a flat, board-like panel. When inflated via the usual valve, this panel can withstand much higher pressures than a normal round tubed IK. We’re talking up to 15psi (1 bar) which is four times more than even the firmest tubed IKs. As we know from iSUp boards (above left), this means the kayak can be be nearly as stiff as a hardshell. The huge popularity of iSUPs in recent years has helped advance D-S technology.
Pressure has long been the weak link with traditional tubed IKs once lengths increase. Floors need I-beams (above left), to act like space yarn and make a flat, wide panel, but they’re expensive to assemble and – without pressure release valves (PRVs, more below) are vulnerable to damage or rupture if over-pressurised through neglect or when left out in the hot sun.
Drop-stitch technology eliminates the longitudinal sagging commonly experienced under a single paddler’s central weight in a longer, old-style boat (left). D-S rigidity enables sea kayak-like lengths of well over 4 metres (13′) which adds up to more room inside, greater speed as well as a better glide (less effort). It’s the same energy saving gained by pedalling a pushbike with hard tyres instead of soft.
Eight to ten-inch diametre side tubes also take up a lot of space inside. DS panels are typically 10cm thick so get round this while retaining the benefits of tubed IKs: light weight and buoyancy. The only downside seems to be bulk: up to 4 kilometres of space yarn in a typical 4.5-metre FD-S IK as well as PVC which is hard to roll up makes the boat twice as bulky as a similar-sized tubeless boat. Drop-stitch is far more effective than using metal frames to support saggy IKs. In my experience this is a poor solution.
Most full drop-stitch (FD-S) Is are made of three flat panels. In a way they resemble a simple, self-assembled three-board wooden canoe(right).
They’re all almost certainly made from Selytech DS PVC (left) developed by Woosung in South Korea. Woosung is the world’s biggest manufacturer of IKs and sell their own boats as Zebec Pro (Z-Pro and KXone). Bic Yakkairs are made in Vietnam but probably use Selytech too; most of the rest are assembled just over the Yellow Sea in and around Shandong, China. Once they get to western markets they typically go from around £700 for a double – a lot compared to a used plastic hardshell.
D-S IKs actually started with easy-to-fit drop-stitch floors (derived from iSUp boards) but retained the round side tubes: hybrids. Many IKs are still made this way which some may seen by some as the best of both worlds. But all the boats on this page are Full D-S. See image below for the three types of IK: tubed (bladdered – can also be ‘tubeless’); D-S floor or Full D-S.
Among many others, Sea Eagle in the US, KXone and DS Kajak in Germany (same factory) plus Bic Yakkair in France all produce FD-S IKs. Aqua Marina Tomahawk is another one, so is a Bluewave Glider; an 18-kilo 4.7-m boat that’s only 76cm wide. Currently, in the UK the price of a Shipwreck ArrowStream has dropped to just £549 for a double (left) with full kit, or 3.4-m singles from £449. That’s about as cheap as an imported and warrantied FD-S gets.
At that price, is it worth the hassle of buying direct from China as JtB did without regrets? I’ve tried off madeinchain.com and AliExpress: either no answer or payment immediately and suspiciously cancelled. If doing so, use a credit card so you have some protection. You probably won’t get a warranty but you should get some buyer protection.
Allroundmarin is an Austrian importer bringing in re-branded Chinese-made FD-S IKs customised with their own colours and features like floor drains through which you can clamp an electric motor. Their 4.7-m model goes for around the same price as a Glider.
Floors: Read This Broadly speaking, FD-S IKs are assembled by wrapping and gluing three D-S panels in a reinforced skin of PVC which protects the panels from wear and abrasion. Some have removable floors, a bit like a footbed slips into a shoe. This makes the floor interior accessible for easy cleaning, rinsing and drying before storage – an important part of IK care.
Less good but almost universal is a D-S floor permanently attached to the floor skin and side panels, but not fully sealed. Water and debris get down in the cavity from each end so some drain valve arrangement as below left is needed to allow water to run out when flushing or disassembling. This is not a self-bailing port, no matter what clueless vendors may claim or owners may think. Open the ports when afloat and the boat will pool with water for sure. Until I realised this, I was puzzled by these drains. So it seems were actual owners. Bluewave Gliders are like this, so are Allroundmarin, Sea Eagle RazorLite, Tomahawk KXone, Shipwreck and anything else with the telltale drain ports.
Such a boat is nearly as much of a pain to dry fully as the bladdered IKs I go on about. There will always be moisture in the long, inaccessible side cavities along the D-S floor edge which you will struggle to dry properly. Proper rinsing and drying matter if you want your IK to last a long time, especially after you’ve been at sea, or when sand and other debris gets in the boat. Seawater causes mildew, staining, odours and possibly rot, so does trapped organic matter, while in the long term trapped grit might rub unseen against the soft PVC until it wears right through (this will probably take years).
A way to eliminate these issues is by fully sealing or ‘wallpapering over’ the side and floor D-S panels where they are not joined with tape: usually the bow and the stern (above left). To drain and dry such fully sealed boats, you simply flip them over to shed the excess water, then deflate, spread out and wipe dry, like the tube-type Grabner on the left. A boat like this would have no crud-trapping, moisture-retaining cavities. The problem with this idea would be the air trapped in this sealed-off cavity would make the boat bulkier to pack: like trying to roll up a partially deflated inner tube. A simple plug would get round that. Pull out to deflate, plug up once pumped up. Fyi: this is all hypothetical. In 2020 Advanced Elements introduced the innovative two-panel AirVolution FDS IK which seems to have no crack between the upper and lower panels. Good for them because, apart from the added labour, sealing the insides is not exactly complicated. For the moment it seems other manufacturers are happy to settle on removable floors or fitted floors with drains, just as some buyers are either oblivious or contented with bladdered IKs with greater drying issues.
Actually their is a worse option: supposedly ‘self-bailing’ FD-S IKs which have little side cavities on the edge of the fitted floor and simple drain holes in the outer skin. There are no closable drain valves. The tellingly unused and unbranded FD-S IK (left) I saw on eBay was like this. I had to check with the seller as there were no photos of the floor. Within an hour it sold for £700, but once on the water the new owner will find their boat filling up from below. It may only be a couple of inches but that water will slosh back and forth as you paddle along, adding several kilos of weight and upsetting stability. You could easily tape up the holes in the outer skin, but this is why what should be ‘bargains’ come unbranded and without guarantees. No brand would risk doing it this way and get rightly hammered by negative customer feedback.
Keel tubes One benefit of having the floor panel loose and separate above the PVC outer skin is you can stick a thin inflatable tube in there to give the hull more of a V-shape. The AirTrek FLex 465 by DS Kajak (and the same-but-different KXone FLex) have these optional shallow inflatable keel tubes (‘AirBone’) under the removable but clamped-down floor which you quickly inflate via a loose hose. It changes the hull shape from flat to V. More speed and a bit less stability is what they claim, and you can easily deflate the keel tube on the move if conditions get tippy. An FD-S IK’s flat floor is one of its less good features, so this sounds like a clever idea. And as said, the floor is removable so it can all be cleaned and dried easily. Sounds like a win-win to me. See the video below or here.
What are they made from? Nearly all brands are cagey about the Selytech fabric. There seems to be a word missing and that missing word is of course ‘PVC‘ – poly vinyl chloride. But not all PVC need be nasty slackraft crap, as this page explains. It may not be considered very green, but the PVC is applied as an air- and watertight coating over a polyester fabric base, just as ‘rubber’ is with Hypalon and its derivatives.
Tracking (going straight) Just about all of these Chinese FDS IKs come with an easily fitted slot-inskeg or tracking fin that’s often as tall as Flipper’s flipper. This means it will drag in the shallows and can’t easily be sat on flat ground. But it’s easily trimmed – or buy a spare and cut it down for paddles which need it.
These FD-S boats also feature rigid moulded bow and stern pieces (above right) to help slice through the water. This is typically a weak point on broad-nosed tubed IKs (above left).
Hardshells and conventional tubed IKs like old Gumotex can also have a curved hull in both axes: lateral (above) and bow to stern curve which is called rocker. The more banana-like the longitudinal profile the more rocker and the easier the boat turns. With the formed bow and stern pieces, box-like profiles and plank-floors, an FD-S IK has zero rocker, suggesting these boats track well but are hard to turn without a rudder. Many owners report that indeed, they glide as straight as an arrow. One French KXone owner admits that after a year of use… ‘It always wants to go straight, even without the skeg‘ and he’s thinking of installing a rudder. Another reviewer from the US says: ‘The 393 RL tracks very well, almost too well. I trimmed 3″ off the skeg for better clearance in shallow water and it still tracks straight and true. It’s easier to turn now as well, another nice improvement.’ Here’s another short review from the UK. This was my experience too with a D-S-floored Moki II and with the Shipwreck, but on the latter was much improved by removing the skeg.
And the flat floor and box profile may make edging – leaning on one edge as you turn or to counterbalance on waves – trickier. You’d need thigh straps to do this but I never got that technical with the Shipwreck I tried. This Tomahawk owner said his boat’s initial (or primary) stability was a bit shaky, but once on edge was quite stable and took a lot to tip right over. This was on flat water. In more dynamic conditions things may happen fast.
Pressure-release valves It’s notable that there are no PRVs on most of these boats, presumably because the very high density of space-yarn means they can handle over-pressurisation when left in the hot sun better than an I-beam floor. The two-panel 2020 AE AirVolutionabove is an exception.
Otherwise, better branded FD-S IKs have clear warnings at the valve not to exceed recommended pressures (left). You’d think the pressure increase in smaller-volume DS floors will be less extreme than fatter I-beam floors. Some claim D-S floors without PRVs won’t last as long as I-beams with PRVs. Much will depend on the quality of the original manufacture/assembly, maintaining the correct pressure and where possible, leaving the boat in the water on hot days to keep things cool.
These boats’ smaller volumes also means they’re quicker to inflate than a regular IK, although the effort in reaching 10psi requires a barrel pump. Tall and slim work better than short and fat: it’s this shape and not the volume which counts. A 4.4m FD-S panel can be filled to 10psi in just a minute; a bit more for the floor.
Footrests, Decks & Skegs Not for the first time I see ideas I’ve tried on my own IKs. In Sea Eagle’s and Airkajak’s case it’s a simple footrest tube with an adjustable strap which I came up with a years ago! It’s so much simpler and more versatile and effective than the mushy pillows still used by Gumotex. KXone and Gliders use a padded strap. In any type of kayak, a footrest helps you connect with the boat and pull in powerful strokes and not slide down the seat. And as an IK doesn’t have the benefit of a hardshell deck to brace knees off, a solid footrest is all the more useful.
The KXones pictured left have optional removable decks. Once you realise this boat is as rigid as a sea kayak but with no deck, adding one (or at least some sort of deflector at the front) may be a good idea for managing bigger waves. A regular IK will bend up and over waves – a stiffer D-S IK will cut through them and may swamp, especially if loaded.
You may like to scroll down and read some of the reader’s comments about issues and returns they’re having with early RazorLites. She mentioned the new D-S boat was less stable, but to me the ‘stability’ of the yard-wide FastTrack is beyond the pale. About 76cm on the 473 is still 30-inches and I felt quite safe in my 69cm-wide K40 right up to the point when it was coming in over the sides (thigh braces helped greatly, I admit). Then again, the 83cm-wide Shipwreck is actually more like 60cm at the waterline and I found the thick seat pad made me very tippy. Removing the 6cm pad from the seatbase resumed normal service.
Some boat specs
Sea Eagle’s 473RL RazorLite was the first FDS IK and the double is 4.73m (15.5′) long and just 76cm (30″) wide. Weight is claimed at just over 17kg (38lbs). The DS panels run at 10psi (0.67bar) and are 10cm thick, giving a massive claimed payload of 340kg.
KXone’s Sliders (right) are designed in Germany but made at the same Chinese factory in Weihai for Woosung in Korea and are rated at 8psi (0.55 bar). It’s unclear if all current Sliders are now FLex models with the removable floor and keel tube option (as described above), or if FLexes sit alongside the regular flat-fixed-floor Sliders. Slider 445 (14′ 7”) • 85cm (33.5”) wide • 17kg • 225kg Slider 485 (16′) • 85cm (33.5”) • 20kg • 250kg Slider FLex 485 80cm (31.5”) • 20kg • 250kg
BIC Yakkair Full HP 24.1m (13.5′) • 85cm (33.5”) wide • 15.5kg • 210kg • 8 psi. There’s also a 4.8m HP3. see video below.
DS Kajak’s extra-long 10psi Airtrek FLex 515 (below) is a slender 78cm wide and weighs 22kg with a claimed load of 300kg. DS Kajak also make a 465 FLex.
You notice the two flat-floor Sliders and the BIC are wider than a Sea Eagle RL, for example. This is because they’re pitched as SUP IKs, in that you can stand in the boat (left). With the popularity of iSUP boarding, this is a clever gimmick. But sit-down paddling performance will suffer. Me, I’d sooner have as slim a kayak as possible.
Lined up against my regularly updated IK compassion table (below), all those dimensions are very much in the ballpark, with the long Airtrek 515 getting a very high L/W Index of 6.6. The DS Kajak 515 is over 2 feet longer and as slim as my Seawave (among the faster touring IKs). The short and wide BIC HP2 comes in at 4.82 – not so good and a bit more than a ‘hybrid’ Thaya.
Good on all these brands for upping the game with their takes on full D-S IKs. It’s a big step in making IKs less ‘bloat’, more boat. Many people commonly mistake them for hardshells. Having spent months looking at loads of images and videos of all these boats, at the moment the 20-kilo DS Kajak 465 is the one I’d choose, except the massive bulk of these things puts me off. The removable floor aids proper drying and cleaning, it’s no wider but half-a-foot longer than my old Seawave, and graphics-wise, it doesn’t give me a migraine. But €1300 is a bit of a gamble. So I’d look at the Shipwreck ArrowStream which I did actually try (review here). For currently less than £550 you get a whole lot of boat in the bag. Whatever you get, make sure you fully understand any possible drying and grit-trapping issues unless you live in a spacious villa in Antibes and plan use your boat regularly. Not everyone may see drying as the deal breaker I make it out to be.
Spotted a mistake or have something to add? Your comments are welcome below.