• Other IKs
• Review: Shipwreck ArrowStream 4.4m Full D-S
• Review: Aqua Marina Tomahawk Air-K 375
• Paddling with a Yakkair Full HP2
• Preview: Advanced Elements AirVolution
• Preview: Decathlon X500
• Preview: Gumotex Thaya
• Preview: Gumotex Rush
• Buying direct from China
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.
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-in skeg 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.
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 AirVolution above 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 2 4.1m (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.
For a Shipwreck dims, see here.
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.