Tag Archives: drop stitch kayak floor

Preview: Gumotex Thaya IK

Updated Summer 2020

thayaop

award

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 (D/S) floor to greatly improve rigidity. The Solar was not unlike my old Sunny, running just 3psi (0o.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 D/S-floor boats, but a basic exercise in simply replacing a floor rather than trying anything more fancy like the Rush of 2020.

decpump

Drop-stitch fabric now makes the complicated hand assembly of pressure-vulnerable I-beam floors (left) redundant. A D/S 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 might be that you need a more powerful high pressure barrel pump (above right). The old Bravo bellows foot pump won’t do anymore.

D/S is normally PVC and made in China, but Gumotex have found a way to manufacture the threading and bond or coat 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 side tubes ought not need the higher pressures I run on my adapted Seawave because the 7psi (0.5 bar) D/S floor greatly aids longitudinal 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’].

thaya-family

The promo video below suggests something revolutionary, but combining D/S with Nitrilon can’t be that much different from doing the same with PVC. It will certainly simplify or speed up assembly and make floors much more resistant to over-pressure damage, low though that risk is with a PRV. Drop-stitch floors supposedly don’t need the 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 D/S floor with a PRV. The assumption is they don’t need it but some claim that D/S floor 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 D/S 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 D/S panels. Initially I thought why? For the backrest and footrest that might make sense but of course you don’t have to pump D/S up to the max to get it’s flat form constraining benefits. Footrests are the usual inflatable pillows. 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.

thaya-red-l

I’ve never tried one, but I do wonder how a flat-floored D/S 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) 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 would be swamped 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 but you imagine the plain floor will roll up more compactly.

For most recreational, flatwater users the Thaya ought to be a nice family boat, but then so is a Solar 3. The Thaya’s rrp is 20% more than the Solar 3 whose days may be numbered.

Drop-stitch IKs: Razorlite, KXone, Yakkair, etc

Updated summer 2020

• Read also Decathlon X500 and Gumotex Thaya and Rush
• … and this illuminating post
Slider discussion on French forum

As predicted in IK Construction a few years ago, before long someone was going to find a way of making a decent IK entirely from drop-stitch panels.

Sea Eagle in the US, and KXone and Airkajak of Germany plus Bic Yakkair in France were among the first to do just that, with three-chamber DS IKs made entirely from Selytech DS PVC 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). The boats are actually manufactured just over the Yellow Sea in Shandong, China. 

There are now several full D/S IKs to be found on eBay under various brands you’ve never heard of. The Bluewave Glider left is an 18-kilo 4.7m footer that’s 76cm wide and goes for just £659 for the full kit, or 3.9-m singles from £550.

Below, Allroundmarin out of Austria are another importer bringing in the same Chinese-made full D/S IKs re-branded under their name and adapted with their own colours and features such as a footrest strap and what looks like a drain hole through which you can clamp an electric motor. Their 4.7m F D/S IK goes for around the same price as a Glider.
In 2020 I took a punt and bought an inexpensive, unbranded full D/S IK (right) off Ali Express in China (it never got sent; refunded).

A fully drop-stitch (DS) IK is made of three flat panels which each run at least 10psi – three times more than a regular tubed IK. In a way, D/S IKs resemble a simple, self-assembled three-board canoe, as shown left. This gives the boat the rigidity (if not the streamlined form) of a hardshell, while retaining an IK’s light weight and portability. Full description of D/S here or keep reading.

D/S IKs started with easy-to-make drop-stitch floors (derived from iSUP boards) but retained regular round side tubes. Some floors were a removable option (Advanced Elements), on others the floor is integrated (Sea Eagle 385; Gumotex Thaya and Rush). The boats on this page are the first generation to be made entirely of D/S panels. See image below for the three types of IK: tubed; D/S floor; full D/S.

Sea Eagle’s tandem 473RL RazorLite, the two larger Kxone Sliders (below) and the Yakkair Full HP are a slick and lean group of full DS IKs. And setting aside the fun element of speed, a fast IK is an efficient and safe IK on which you can range further or retreat quicker if conditions change.

I don’t claim to have any experience of these new boats yet: it’s all the usual online speculation IK&P is so well known for. I did try to buy one direct from China as this guy did, but got no reply. Sea Eagle and KXone make some hugely wide bladder tubed ‘American’ IKs – recreational boats which are great for standing up and fishing from while your dog scratches its ear, but are less suited to all-day IK touring which is the niche activity we like here at IK&P.

Sea Eagle’s 473RL RazorLite 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.

slides

KXone’s two similar boats (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):
Slider 445 (14′ 7”) • 85cm (33.5”) wide • 17kg • 225kg
Slider 485 (16′) • 85cm (33.5”) wide • 20kg • 250kg

BIC Yakkair Full HP 2  4.1m (left; 13.5′) • 85cm (33.5”) wide • 15.5kg • 210kg • 8 psi • Video below: barely a millimetre of sag!

Air Kajak’s 10psi Airtrek 465 is 79cm wide and weighs 20kg + seats.

kzostand

You notice the two Sliders and BIC are 10cm wider than the Sea Eagle RL. This may be because the 2017 models at least, are pitched as SUP IKs, in that you can stand in the boat and work those core muscles! With the popularity of iSUP boarding, this is quite a clever sales gimmick and an activity which is easier to do with a wider floor, although sit-down paddling performance will suffer.

Lined up against my latest IK compassion table (below), all those dimensions are very much in the ballpark, with the slim Razorlite getting a very high L/W Index of 6.22. The RazorLite 473 is over 20cms longer and a couple of cm narrower than my old Seawave (among the faster touring IKs). The longer but wider 485 Slider has an LWI of 5.7 – same as my Seawave. The shorter BIC comes in at 4.82 – not so good and a bit more than a ‘hybrid’ Thaya.

These DS IKs are simply three flat slabs of DS fabric. Conventional tubed IKs like old Gumotex can vary the diametre each chamber (floor and two sides) to help give a curved hull in both axes, particularly each end of the floor. Somehow, even with the formed hull and stern pieces, the plank-like floors of a DS IK have zero rocker, suggesting these boats will track very well, but may be hard to turn.

One French Kxone owner admits that after a year of use… son défaut c’est qu’il est hyper directeur, même sans dérive … [‘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 is because some of these boats effectively have a frontal keel (right: Sea Eagle Fast Track) or a very sharply defined bow piece. I can’t help thinking that having to fit a skeg to the front of a boat is an admission that a flat hull won’t track well, even with a conventional skeg at the back. A frontal keel or skeg-form bow will make a boat track very well but make it very hard to turn, especially when it’s over 4.5-m long.

And the flat floor and box profile (left) may make edging – leaning on one edge as you turn or counterbalance on waves – trickier; the secondary stability (leaning right over) may be on a knife-edge. You’d need thigh straps to manage that, but anyway, it’s all speculation – the proof is in the paddling.

What is Dropstitch?
For the full story on drop stitch (D/S) click the link
Short version: the mass of non-stretch ‘space yarn’ stitched between the two woven fabric surfaces of a hull panel (above left) enable much higher pressures while crucially constraining the panel from ballooning out. We’re talking up to 15psi (1 bar) which is four times more than what even the better regular tubed IKs run. Pressure has long been the weak link with traditional ‘lilo’ IK floors which need I-beams (above right; a similar idea to DS), to retain a flat shape. I-beams are expensive to make and – without PRVs – vulnerable to damage or rupture when over-pressurised through neglect or when left in the sun.

Easy-to-make round side tubes can handle high pressures fine, but take up a lot of space which makes for a wide and tall but also a cramped IK – one of their biggest failings. DS panels get round some of this. High pressure is also desirable in an IK to reduce longitudinal sagging under a single paddler’s weight (above). Some manufacturers use metal frames to minimise this, but in my experience it’s a clumsy solution.

Using DS technology these kayaks can easily attain hardshell sea-kayak-like lengths (and so, speed) because the high-pressure DS hull makes a rigid box-like structure; the boat won’t ‘taco’ or fold up between waves as most long 0.2 bar/3psi IKs like a Gumotex Solar 3 will do.

It’s notable that there are no PRVs on these boats, presumably because the very high density of evenly spread space-yarn and the can handle over-pressurisation when a boat is left in the hot sun. Some do have clear warnings at the valve not to exceed recommended pressures (left). You’d think the pressure increase in smaller volume D/S floors will be less extreme than fatter I-beam floors. These boats’ smaller volumes also mean they’re notably quicker to inflate than a comparable regular IK, despite the effort in reaching 10psi which will require a hard-bodied barrel pump.

Some claim D/S floors won’t last as long as I-beams with PRVs. That may be true and 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.

The Sea Eagle features two drain valves in the floor – I’m not sure why. To drain an open IK, you simply flip it over, like emptying a bowl. Drain valves seem another thing to go wrong, as RazorLite owners have already found (see below). It’s not like these are self-bailing boats – open the valve and you’ll be sitting in water. Kzone and Airkajak now have the drain plug right in the stern (left) but it still makes little sense. As for the red Kxone graphic above; I’m not sure I fully understand it, but there appears to be a water-collecting cavity between the floor and the sides which requires draining, once deflated.

Selytech-DS-Fabric-Construction_2-yellow-1024x569

Both brands are cagey about the actual Selytech fabric. There seems to be a word missing and that missing word is of course ‘PVC‘ – poly vinyl chloride: the Devil’s Fabric! But not all PVC need be nasty slackraft material, 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 with ‘rubber’ hypalon.

sai13

These boats also feature rigid moulded ends in the one-piece body to help slice through the water. This element of streamlining is typically a weak point on ‘broad-nosed’ IKs (left) where a sharp bow and stern are difficult to fabricate purely from inflatable tubes. The grey PVC Incept on the left (based on the old Semperit) does a pretty good job and was a fast boat. The bulk of these rigid fixtures, as well as the dense D/S panels, may make PVC D/S kayaks less easy to pack compactly than regular synthetic rubber IKs.

Not for the first time I see an IK manufacturer use 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, versatile and more effective than some of the mushy ideas I’ve seen used on IKs. Kxone use a padded strap; less good IMO.
In any kayak, a solid footrest helps you connect with the boat and pull in powerful strokes. And as an IK doesn’t have the benefit of a hardshell deck to brace knees off, a footrest is all the more useful. Even then, I’d say both these D/S IKs would benefit from thigh straps, especially the slimmer Sea Eagle. Both boats are spacious inside, with little chance of feeling nicely wedged in, like a packraft.

The KXones are pictured with a removable deck for single or double paddlers. 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 waves more than a metre high. A regular IK will bend with waves a little – a stiff D/S IK will cut in and may swamp, especially if loaded.

Over in Canada IK World ran a comparison between her old style D/S-floored Sea Eagle FastTrack and the 393 solo Razorlite, as well as giving a fuller recreational review of the 393.

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 76-cm on the 473 is still 30-inches and I felt quite safe in my 69-cm wide K40 right up to the point when it was coming in over the sides (thigh braces helped greatly, I admit). 
Both boats appear wide but the D/S sides taper inwards towards the floor, so they’re narrower than they look. And both come with an easily fitted slot-in skeg that’s as tall as a dorsal fin so will drag in the shallows. Perhaps that pancake-flat floor needs a big skeg to keep it on track, but of course it’s easily trimmed.

iu

I’ve never been a great fan of Sea Eagles’s regular, PVC watersofas (exemplified by that hideous thing on the right), but good on them and KXone for upping the game with the full DS IKs. It’s a big step in making IKs less ‘bloat’ and more boat. Many people are already mistaking them for hardshells.

Inflatable Kayak Construction Part 2: Hull Forms and Rigidity

Part 1: Materials and Fabrication
See also: Drop stitch IKs (or more below)

Updated Summer 2020

An inflatable kayak differs from a hardshell in many ways. An IK is usually wider and sits higher in the water because the sides and floor are effectively several inches thick, not a few millimetres as on a SinK (‘sit-in hardshell kayak’).

grabanana

While length-for-length an IK is usually lighter than a SinK, it’s rarely as rigid. On a short, rock-bashing, creek boat this can either be unnoticeable or even a slight advantage when it comes to impacts.

But here at IK&P we’re into long IKs of 3.6m (12 feet) or more. Years of experimentation have proved that this adds up to a do-it-all boat that’s manoeuvrable on rivers up to WW3 and fine for coast hopping up to Force 4. Such a boat can either carry a second paddler or a solo camping payload for a few days touring while rarely weighing more than 18kg or 40lbs and so can be carried over short distances.
Problem is, when an IK gets beyond a certain length it can sag in the middle with a single heavy paddler (me?!). As on my old Feathercraft Java (below), even with rocks piled in each end or my ‘uphill‘ Grabner, above left. There are various ways of making a long IK rigid, but first…

cons-2bots

Hull profiles
A hardshell sea kayak can have various hull profiles that, combined with other design elements defines the boat’s stability in various sea conditions. The picture on the left may be merely down to timing but illustrates how a very long SinK on the right runs more level than an IK bobbing about on rough water, partly because the hardshell is heavier and less buoyant, but also because – like a 29-inch MTB wheel – a long, slim kayak ‘flattens out the bumps’ better than a 26-er. Some sea kayaks with V-shaped hull profiles become more stable the rougher seas get but at the cost of stability in flat water.

slidercut
sai13
Left: Grabner Amigo – right Incept K40.

The flat and wide hull profile of a traditional IK is not so sophisticated, nor is the boxy (hard chined) profile of a full dropstitch (F D/S) IK (right). For better or worse, most IKs are as stable as a raft. The key is to find a balance between reassuring stability and performance-killing width. On an IK I find the optimum width is around 32–27″ (81–69cm). On rivers or at sea an IK hull is usually very stable until things get exceedingly rough. I’d guess that the two hulls pictured left (a red Grabner Amigo and an Incept K40), the less boxy red boat would take more leaning over (or steeper waves) before it suddenly tipped. However, it’s pretty obvious why the grey Incept was some 20% quicker through the water, as was my slender FC Java.
Note that the width of an Full D/S IK can be misleading as the flat sides taper in to the floor. Above right a Sea Eagle Razorlite listed in the table below as 76cm and which is fast, but some find a bit tippy.

The Incept was 3.5 inches narrower than the Amigo and has a more pointy bow (its stiff fabric and being 15% longer were also factors). And yet, this 27-inch (67cm) wide Incept could never be described as ‘tippy’ even in seas up to F5-6 (other problems did occur).
It all proves that an IK doesn’t have to be ridiculously wide (as left) to be stable. Many, many otherwise functional-looking IKs are up to a foot wider than the Incept. Even if you are extremely nervous about padding and stability, such width is excessive and makes paddling inefficient.

cons2pads

Stability and centre of gravity (CoG)
Having said all that, an IK needs to be a bit wider to compensate for the fact, that compared to a SinK or a packraft, you’re sat higher above the water on an air floor and probably on an inflatable seat too (graphic, left). This adds up to a higher centre of gravity which affects stability, just as a 4WD is top-heavy in turns or on slopes compared to a McLaren F1. Your butt is the axis on which you pivot when wobbling/capsizing and on a hardshell, a folder or a packraft you sit just an inch or two below the water level: lower CoG = better stability without resorting to width.

AESE

Then, when you factor in less common self-bailing IKs, with an even thicker floor to be above the general water level, again the boat becomes less stable unless it becomes wider. You can see how high the floor appears on the self-bailing AW StraightEdge on the left and the Feathercraft Java, below.

javabailer

Also, your physique/size can also produce an impression of instability in otherwise well-liked boats that most paddlers find fine. At my XL size, I found my old Gumotex Sunny’s 30″/76cm beam was more than enough and at 27″ my Incept was also fine. But the 28-inch Java (above) and even more so the as wide Mk1 Safari (a self-bailer) were a bit tippy. The graphic below shows a regular IK in calm water and then swamped in rough water (centre). Right is a self-bailer like the Java or StraightEdge which drains in the same rough conditions but requires a thicker floor and/or higher seat to keep you dry. Result: IKs like Java or Safari Mk1 get tippy (for some), or you sit in water (not ideal) or the IK becomes over-wide (also not ideal but the best compromise for white water).

ikbailers1
comeonibeam

IK floors: I-beam and drop stitch
Traditinal IK hulls had three chambers: two round side tubes and a flatter, wider floor composed of many interlinked tubes (left). And in case you’re wondering, an inflated floor is an important element in an IK’s buoyancy. Obviously, round sided tubes are easy to make and take on the required form on inflation. Providing it’s well made, modest over-inflating is OK as the round profile distributes pressure equally.

Steel-IBeam
javasection

The flatter, lilo-like floor is another matter. To make this section the floor is joined top to bottom with I-beam fabric dividers resembling the steel beam on the right. It’s said this is the most labour-intensive and expensive part of traditional IK fabrication and explains why easy, slip-in bladders are preferred by most manufacturers, as on the Java, left. It saves time, effort and cost. Without I-beams or other constraints, once inflated the floor would balloon into a useless rounded form.

sempauto - 8

But with I-beams too much pressure can pull the floor dividers apart. Result: the floor balloons, the hull becomes deformed and a repair is very complicated or expensive. This is why some IKs including better Aires, some Gumotexes, bigger Grabners and Incept Ks feature a pressure relief valve (PRV) in the I-beam floor. Even though this part of the boat is in the cooling water, it is vulnerable to damage from excessive pressures which can occur when an IK gets hot when left out of the water. Although it had four separate bladders as opposed to an I-beam floor, I learned this lesson the hard way when my day-old Feathercraft Java went Krakatoa on me one sunny day in Colorado.
Following that disaster, one thing I liked about my Incept K40 was it had PRVs on all three chambers. I no longer needed to be paranoid about exploding my £1500 boat by accidentally allowing it to overheat out of the water. I could leave it on a car roof or a beach all day and air would purge harmlessly via the PRVs at the price of being a bit limp once it all cooled down back on the water. A quick blast with the K-Pump was all that was needed. On my Seawave I added PRVs to the two side tubes to get the same benefits.

twinpointer

Other ways of making an IK hull stiff
Whether your IK is bladder (as left) or tubeless, one way to achieve a rigid hull is to use twin side beams; two thinner tubes stacked over each other as pictured left. There may not seem much in it, but two tubular sections resist longitudinal bending better than one big tube, and all with a negligible gain in weight. This design also has the advantage of making a slimmer boat compared to a fat, single side tube. Higher sides without width also keep out waves but do make more windage – the bane of IKs. Examples of twin side tube IKs include the Grabner Holidays, Incept Ks and the Sevylor above, the old Semperit Forelle (the original modern IK) and Gumotex Seakers. At the time, Gumotex weren’t able to make a 5-metrelong Seakers out of Nitrilon that was suitably rigid so the Seaker (below) used a Korean PVC-coated fabric called Mirasol, but ended up weighing a staggering 34kg – double the Incept.

backbone

A cruder method includes fitting metal frames or spars. Advanced Elements offer an optional Backbone (right) for some of their kayaks, though I’m still unsure whether this is as much to impart more of a ‘V’ into the otherwise flabby hull floor and so improve tracking and speed. A picture here, and a forum full of discussions somewhere here. As the picture right at the top of the page shows, the metal frames in the FC Java (see also green graphic above) didn’t keep that boat rigid, at least with my weight.

ner - 13

The newer Neris Smart IKs (left) use more substantial metalwork based on their folding kayaks. Using metal frames is a valid way of gaining stuffiness, but Incept, Grabner and now dropstitch have proved that you can design an IK without resorting to such measures. Just as I’ve found with the Java and Grabner’s alloy backrests, incorporating bend-prone metal bars with inflatables isn’t a good idea. If nothing else it makes damage-free transportation more of a gamble.

mod-bendloads

This sagging was always a problem on my 13-foot Sunny (left). While paddling in France one time I tried putting a 1-metre plank under the seat to reduce the mid-sag. It did seem to give me an extra inch or two of draught in the shallow river. Later, I tried a couple of straight branches jammed into the cavity between the floor and the side tubes.
My unscientific impression was that by levelling the boat out in the water the Sunny was indeed faster and more responsive. The fact that later on the river sticks popped out of their slots through some rapids suggested how much the 0.2 bar (3psi) Sunny flexed in rough water. Later I tried fitting some chopped-down cheapo paddles. Some form of attachment for the poles needed to be glued to the 3-inch wide flat section where the floor meets the side wall (more here). I got as far as this but then gave the Sunny away. Had I finished the job I’d have expected a little more response to the paddling stroke with a less flex in the waves.

superman
dsfabric

In the last few years drop stitch (D/S) panels have appeared on a newer IKs. This technology is derived from the popularity of inflatable iSuP boards (above) which clearly need more pressure than your average airbed or IK. Lord knows how they make it, but it’s a way of joining two sheets of coated fabric with countless loose nylon filaments, all the same length (left).

airkayaks

When the two sheets are sealed to make a chamber and then pumped up, the space yarn acts like multiple ‘I-beams’, distributing the tension over the entire surface area. Result: pressure can be up to 10 psi or nearly 0.7 bar’ – four times than a tubed IK, making the boat much more rigid. More on DS IKs here.

inflatoe

Incredibly, in the late 1950s Goodyear used a the same D/S technology to design an experimental inflatable aircraft, the Inflatoplane (above). A light and portable plane, not an inexpensive inflatable decoy as armies have used previously. It did actually fly but as a project was abandoned when a valid military use for ‘an aircraft that could be brought down by a well-aimed bow and arrow‘ couldn’t be found. Now there are IKs like the Kzone Slider below which are fully made from DS panels.

SLIDER

They are only just finding ways of making a D/S panel that’s anything other than flat as an ironing board, but they’re getting there – the Decathlon Strenfit X500 (below) currently leads the way. While full DS will make a kayak very rigid, the smooth, flat underside and basic, box profile may make handling in rougher water tricky. One side benefit of the I-beam floors on ‘tubeless’ IKs is the channels formed by the parallel tubes create a keel effect.

sea385skeg

On the Sea Eagle 385 they’ve incorporated a drop-stitch inflatable front keel (left) that looks rather exposed and prone to damage. You’d also assume this makes turning difficult, although with enough paddle cranking and some edging any IK can be turned easily enough.

Now they can manufacture DS panels which are more sophisticated than the slab-like platform shown below, mimicking the complex forms and curves of a molded hardshell kayak. It marks a big step forward in IK design. Currently the Gumotex Rush (part–D/S hybrid) and especially the Decathlon X500 have upped the game. More than just 3 planks making a paddling trough, Gumotex have managed to integrate D/S panels into the bow and stern, giving a more hydrodynamic form on the sides.
Drop-stitch is the future of IK design and I wouldn’t be surprised if it somehow moves towards packraft floors too. Longer boats like my Nomad S1 could benefit from the added support of a separate D/S floor.

splashmatter