A to Z of Inflatable Kayaks

a2zik

halforts
sevy4-1
Gumo Seawave and an ancient Semperit Forelle,
one of the original IKs from the Sixties.

Inflatable kayaks are a bit like mountain bikes. You can buy a blinged-up overweight piece of junk with ‘full suspension’ from a superstore for under a hundred quid. Or if you’re serious about enjoying cycling you can buy something decent that’ll be a joy to own and ride for years.

They don’t make crap hardshell kayaks or canoes; a simple rotomolded plastic boat can work much like a composite kayak. But they sure make some rubbish IKs which leads to the assumption that all forms of inflatable watercraft are slow, floppy, over-wide, leak-prone pool toys little better than a lilo.
That’s what I thought until I actually tried one on Idaho’s Snake River back in 2004. I nearly bought that boat right on the spot.
As with owning a nice bike, a quality IK inspires you to go out and try new things and enjoy yourself while you’re doing it. Here is my ‘IK 101’.

A

az-potab

is for an IK’s advantages over hardshells, including Sit On Tops (‘SoT’) and folders. IKs offer compact storage of course, as well as lightness in manhandling and ease of transport in a car, on a train, a plane or on your back (left).
Most IKs are undecked and open and so, like canoes and SoTs, are easy to load up, get in or remount from the water. And compared to a ‘skin on frame’ folder (see ‘F’) they’re more robust in terms of getting knocked about. You can lash an inflated IK straight onto a car roof without damaging either. And even when full of water, an IK can’t sink. Unlike our chuckling friends below… 

Laughing all the way to the bottom

B

az-swamp

is for self-bailing, the ability of an undecked inflatable to shed water through drain holes in the floor.
It means in rough conditions a boat won’t fill right up nor need bailing with a pump or bucket, as I needed to do ever 20 minutes while crossing Shark Bay (left).

On a kayak that extra floor height creates instability or a high centre of gravity, which (as with SoTs) can only be mitigated by adding width – and width kills speed and efficiency. The better solution to swamping in an IK is a deck – see below.

foragflor

With a packraft; the added width doesn’t create the same kind of stability issues, especially on bigger boats like the Alpacka Forager (left) whose self-draining floor is shown left.  More on self-bailing here.

cropped-ikbailers11.jpg

Hard charging whitewater rafts need to be self-bailing of course, but in a raft you sit well above the wet floor (left, Animas River, CO).
SoTs (Sit on Top hardshells) are self-bailing too, but an IK is not so well suited to self-bailing because the inflated floor must be thick enough to be above the water line inside to keep your butt dry. Below: this 1980s Metzeler Jumbo whitewater boat used massive chunks of foam to get you up high above the swill. At least the thigh braces will greatly help in controlling the boat.

B is also for bladders. See Construction (below).

C

az-cap

is for capsizing, the fear of which draws many beginners to SoTs and open IKs. If you fall out of an open IK in deep water it’s dead easy to flip the boat back upright and crawl back on, all without help, paddle floats and bilge pumps and in as little as 25 seconds. That can mean less risk of hypothermia.
Doing the same in a hardshell takes several minutes and can be difficult when alone in rough water; and once in, the flooded hull of the unstable boat will require pumping out. That’s why if paddling alone and far from shore, being able to roll a hardshell first time is such an important skill. With an IK you just flip the boat upright (if needed) and crawl back aboard.


C is also for IK construction. There are two ways of making an IK: having ‘sleeves’ in an ordinary fabric hull, which then take inflatable tubular bladders or sponsons (right, an Aire ‘cell’), rather like an inner tube gives shape and firmness to a tyre. Or a more expensive ‘tubeless’ method – simply forming and sealing a tough hull fabric skin and then fitting valves. More on construction here and here.

Certification, Conformity or Accreditation are another bunch of C words that cover IKs (but not packrafts). This can refer to the standard boats are made to but also regulations for permitted use which varies from territory to territory.

ISO is a global standards organisation probably not recognised in the US which has the similar ANSI. The UK the BSI adopts the ISO standard (see below)

As far as I can tell, ISO 6185-1 covers standards for construction and use of inflatable kayaks, but there’s no way of knowing exactly what it is without buying a copy for up to £214 from the BSI (less from ISO in Switzerland).
In the US ANSI adopts standards laid down by the American Boat & Yacht Council (ABYC) which then lead to certification by the National Marine Manufacturers Association (NMMA) which is accepted by the US Coast Guard (USCG). Are you keeping up?
You will see the NMME label on American-branded IKs like Intex, Sevylor (above), Sea Eagle, Advanced Elements whoare all listed as NMMA members. But notably NRS, Aire, Hyside or even Innova (Gumotex North America) are not listed. It’s unclear to me if the first ‘M’ in NMMA means regs and rules only apply to use at sea. NRS, Aire, Hyside mostly make whitewater rafts.

In Europe there is the well-known ‘CE’ standard but according to this directive, paddle boats are exempt, though can be voluntarily submitted (as Grabner do – ‘Amigo’ above left)

What does it all mean to the owner/user? Not that much. Some NMMA-tagged IKs I would not choose to paddle at sea alone, but safety warning labels on vinyl cheapies are clear. The most reliable way of telling if a boat’s any good is the same as it’s always been: its reputation among other genuine users. These days that’s easy to establish online. As for paddling rules and regs on river, lakes or sea: that all depends on where you live.

D

bilge

is for an IK’s disadvantages over hardshells and folders. These include some 20% less speed over a same-sized hardshell, and up to a point, less control in white water and rough seas when things get very technical, although see thigh straps.
An IK’s lightness, buoyancy and greater hull mass above the water line also makes it more susceptible to winds, especially at sea. If you fall out of an IK in such conditions, the boat can get blown away fster than you can swim after it. Like canoes, open IKs will swamp in rough conditions. After a river rapid this isn’t usually a problem, but at sea it could be, without a bailing jug or bilge pump (above right).

seawave2dek

Talking of which, D is also for deck. Some IKs have them, either permanently fixed like some Advanced Elements, the Gumotex Swing and Framura. Some can be attached with velcro as on the Gumotex Seawave (above), or less elegantly with straps for Grabner IKs which must be laboriously glued to the hull, or unzipped and rolled to one side like the Incept, below. When combined with a spray skirt, a deck avoids swamping and splash and also keeps you warm, but it can also mean getting too hot, plus loading or hopping in and out becomes less effortless. There’s more compelling evidence for open boats here.

k4bandy

D is for drying. Don’t underestimate this. You want to dry your IK properly before long periods of storage to prevent mildew, odour and discolouring (hypalon-like fabrics ought not rot).
Tubeless (non-bladder) IKs without a deck (below, a Grabner Amigo) are much quicker to wipe clean and dry than bladder-type boats. If you live in the UK as opposed to sunny Sydney, that makes a difference. Shell & Bladders IKs, as left, take a lot more work to clean, rinse and dry properly. More here.

az-quickdry

Not finished yet.
D is for dropstitch panels which are increasingly becoming a thing with IKs. Derived from iSUP boards, it’s a clever way of constructing flat inflatable panels (below) which can also take much higher pressures and so are much stiffer, like a hardshell.

For years IK and RIB chambers have been made from round tubes because, like a balloon, the pressure is spread equally and there was no other way to make an inflatable chamber. Round side tubes aid stability and buoyancy but take up a lot of space in an IK which can be both wide and cramped. Lately IKs are being made entirely from DS panels (below).

slider2-www.kxone.eu

One problem with these DS IKs is the flat floor: OK for a paddle board or a raft but not so good for a kayak. The rounded tubes of a conventional I-beam floor (see images under H and I) adds a useful tracking element as well as resistance to side winds, though a skeg can see to that too. These DS-floor IKs do seem to have massive skegs as well as additional skegs or shallow frontal keels (above left) to aid tracking.

E

mull07

That’s paddling efficiency. The greater width, freeboard (above-water height) and sometimes hull flex of an IK are all disadvantages over hardshells.
Minimal width, high hull pressures and certain types of fabrics and hull designs minimise all this. Efficiency means it takes longer to get tired: that’s important at sea.

F

az-fold

is folding kayaks. While they have the same advantages of storage and portability as IKs, they’re usually a heavier, more expensive and are more fiddly to assemble quickly (left). But once on the water they appear and perform more like a hardshell. They also possess a certain enthusiast’s/traditionalist’s cachet which is unknown to IKs.

Nifty little Pakboat

Despite all this I prefer IKs over folders because:
• they’re less effort to set up and break down – no awkward frames to assemble
• they’re more robust: you can bash into rocks and generally knock them about – framed folders can snap or bend poles in shallow rapids, or grind on the hull skin, and need care lashing down securely (on a car roof) when assembled
• with robust brands of IKs the puncture risk is much smaller than people think. Me: 14 IKs since 2005; only 1 puncture.
• most IKs are open decked – I prefer that. The blue Pakboat (left) is an example of an open, canoe-like folder

F is also for flotation. One good thing with an IK is that it cannot sink which is why in the US many first descents of extreme whitewater have been done in IKs: there’s less chance of getting pinned or otherwise entrapped. Check out the videos on this page; the same boat at sea and, bottom of the page, skimming over a massive wave train.

G

az-glues
ami-poly

is for gluing. If you get into IKs you want to get good at this. Rubber- or PVC/PU-based boats require different glues. On the left, from the left: Gumotex Nitrilon glue (crap), Grabner EPDM glue (never tried), Bostik 1782 (not bad) and SeamSeal and Aquasure (‘Aquaseal’ in US) for pretty much everything. There’s more here including two-part glue (right) which is the best of all.

G is also for glide: what most IKs won’t do as well as a light hardshell as they don’t have the weight-momentum or bow shape to slice through the water. That’s why minimal width and high hull pressures are worthwhile.

H

nk4-frontal

is hull shape and design. A folder or hardshell’s hull skin, including the floor, is a fraction of an inch thick. An IK’s side is made of a tube up to 8 inches thick and a floor at least half that. This means less storage space inside a slim boat, as well as added height and so centre of gravity, which needs added width to preserve stability; and width reduces performance. More about that on the construction pages.

An IKs floor is wide and also relatively flat, like a canoe. That means in side waves the boat leans over with the wave where, for example, a narrower hardshell with knee braces can be kept upright and in balance. On the left you can see this yard-wide IK was so buoyant it popped out of the frothing pile like a cork and I was ejected. A narrower hardshell may have driven through the pile.

H is also for hypalon and its derivatives (Pennel Orca, Nitrilon, Nordel); all tough [synthetic] rubber-based fabrics once commonly used for whitewater rafts and these days on many better IKs and folders. More here.

I

bic
sempauto - 8

is for I-beam floor – the old way of making a flat floor of parallel tubes, but which is prone to ripping apart at high pressures. More here and see also under PRV, below. See also dropstitch, above and IK autopsy.
I is also for the image of IKs, what they look like and what people think of them. If a sleek, kevlar sea kayak is a handmade Italian stiletto, then a dumpy IK like the one below, is a fake Croc. Even my old Incept – among the fastest touring IKs you can buy – looked like a squashed torpedo and my later Grabner Amigo could have been a prop out of 1001 Nights.

ot-sevy330

Holidaymakers with no interest in BCU accreditation or mastering J strokes buy cheap IKs, zig-zag about, get blow down the shore when the wind turns, and end up fed up and selling the boat.
The same calamities can befall inexperienced holidaymakers in hardshells too, but IKs’ user-friendly accessibility over hardshells attracts less serious and less commited recreational users. In the UK the demonisation of all inflatable watercraft as ‘beach toys’ by some hardshell enthusiasts can be tiresome. In the US and especially in Europe, I and others have found paddlers are less judgemental towards IKs.

j

J is for the letter that comes, funnily enough! – between I and K. J is also a type of canoe stroke. Besides Feathercraft’s Java IK, your suggestions are welcome.

K

az-kayak

is for hardshell kayak, what you may well progress to if you really get into sea paddling and/or acquire the space to store and means to transport one. Or live right by the water.
It sure is great to just hop into a boat on a whim and paddle away, although when staying by the sea I leave my IK pumped up for weeks at a time.

L

az-loader

is for loading and getting in. An open IK is as easy to load and mount as a canoe. You feel less hemmed in than in a decked hardshell, and more out in the fresh air. It’s like driving a convertible.
Because of this you’re much more inclined to hop out and explore a remote beach or uninhabited island, compared to all the faff of the skirt and the dismounting dance of a tippy hardshell. What is not to Like?

L is also for length. Soft or hard, a longer kayak is a faster kayak. A typical solo sea kayak is 17 feet long, but when an inflatable gets beyond a certain length (and has a heavy paddler) it sags in the middle and – like an under-inflated tyre – that takes more effort to move. Some makers get round this longitudinal sag with metal frames, or twin side tubes or high hull pressures, including very high pressure dropstitch floors. This is the most effective solution.

az-lighthead

L is the first letter of the word light, too. The boat on Yves’ head above weighs just 11kg, and that’s made from tough Nitrilon suited to whitewater rafts. My Seawave with newer lighter Nitrilon weighed just 16kg once I ditched the original seats. That can be just about be managed alone under arm or on the shoulders between a car and the water, or of course checked in as airline baggage. The best touring IKs with room for up to two people need not weigh more than 18kg or 40lbs. See table below.

Along with the innate buoyancy, this lightness can work against you if you fall out on a windy lake or at sea – the boat could blow away quicker than you can swim after it. If you think this might happen attach yourself or your paddle to the boat (the paddle will act as a sea anchor).

L might also include leaks. Legitimate PRV activity excepted, I’ve found my IKs will barely lose air for weeks on end. If you do have to make repairs, see here.

M

hypalon fabric

is for material – or more correctly the fabric from which an IK is made. Proper IKs are made of a nylon or polyester woven fabric (‘skrim’) base onto which PVC, PU or a type of rubber is bonded to coat both sides with a waterproof and durable layer. Cut sections are then either glued by hand or heat/RF welded. This is what proper IKs, RIBs and commercial whitewater rafts are made from. There’s loads more here.

A 40-year-old hypalon IK. I replied an L tear (inset) but then the old rubber coating proved porous so the boat was a write off. Out if interest, I sawed the boat in half to inspect the I-beam floor and also tried to pull off the hypalon patch I had glued on a few days earlier. The Polymerise glue did not separate. Instead the hypalon coating of the patch (pink, left) stayed glued to the boat and separated from the patch’s nylon core (white, right). Also bits of old orange boat hypalon pilled away. But the glue did not separate.
glob

Cheap IKs are made from thin PVC that’s squeezed out of a giant tube somewhere in southeastern China and has no fabric base to contain stretching. Keeping pumping or let it get hot in the sun and it’ll burst like a novelty globe or a knotted bin bag. Like slackrafts, these cheapies can be punctured by little more than a sharp noise, and may only last a few months, or as I’ve found, days.

N 

Well, the best I can come up with is names, the regrettable European practice of using infantile IK names like Sunny, Fun, Twist, Guppy, Amigo and Holiday, which doesn’t help shake the wretched beach-toy image, though probably helps sell them to the masses. Elsewhere and lately, they seem to come up with better names: MaverIK; Lynx; Trinity, Mega and Seawave.

O

az-hot

is for overheating. Because an IK is a pressurised vessel, if left in a hot sun the air inside quickly expands and pressures can more than double. This can burst a boat or rupture an I-beam floor or bladders as I and others have found.
Some IKs like Incepts have PRVs (see below) on all three chambers which will purge excess pressure, though when the boat cools down back in the water it’ll be less firm and may need a quick top up.
Never leave an IK without full PRVs in the sun on a hot day for long. Left in the water, the floor will be OK and a splash on the exposed hull sides won’t do any harm once in a while. I fitted PRVs to the side chambers of my Seawave.

P 

grabguage

Punctures and repairs. I’ve owned 14 IKs and had a small puncture in one. In other words, with less care than you might expect, proper IKs are very robust, while paddling with a PVC slackraft, it punctured within minutes. Barnacles and concrete will leave surface scratches, just as they do on hard plastic. If it’s a deep gouge down to the fabric, apply a coat of Aquaseal sealant. More on glue and repairs here.

az-prv1

P is also for pressure release valves (PRVs) as explained under O and here. The one on the left is working correctly. Try and keep your pressure release valves clean. If sand or grit drops into the well, it can lodge on the seal as the valve purges and cause a poor seal until it’s blown free. Until recently I never used a pressure gauge, I just pumped until firm or until a PRV hissed. My Grabner had no PRVs but ran high pressures so I used a gauge (right). See also inflation valves.

P is also for pumps and let’s not forget P is for our good friends: Packrafts!

Q 

grabincesped

equals quickness aka: speed. The fastest IKs I’ve had are around 15% slower than a comparable hardshell sea kayak – flat-out at just over 5 mph vs 6 mph. It’s probably the same for whitewater IKs over a day including flat water. Speed – or at least efficiency – can be an important factor if heading out to sea. You want to be sure you can get back in against an offshore wind before you run out of steam.

R

az-ruda

Rudder. I’ve had one IK with a rudder, a long 4m+ boat, but being a fair-weather paddler I can’t say I miss it on other longer boats, even if it did make sailing a little easier. I nearly changed my mind but then I didn’t

R is also for rinse – what you should do after every sea paddle before drying up for long-term storage.

azrocker

Rocker is another thing starting with R, and doesn’t mean chap in a leather jacket beating up mods on the seafront. In kayak terms rocker refers to the curve of the hull in profile, bow to stern. More rocker or curve (blue boat, left) makes turning quicker; less rocker improves tracking. A long boat will also track better than a short one, and a skeg can make anything track well, while a rudder helps a long boat turn fast and also correct the tracking against a sidewind, so you don’t have to paddle hard on one side to keep straight.

S

gumoldnewskeg

is for skeg (left) a fixed rudder or tracking fin to help your boat go straight. Hardshells have retractable skegs which are more for managing sidewind deflection, as explained with rudders, above.
Do you need one on an IK?
See here.

ami-th3

S is also for stability, why people prefer IKs compared to some kayaks.
And S is also for sponsons: see construction or here.
Not finished yet. S can be for sea kayaking: within limits and typical coast-hopping norms, quite achievable in many IKs. It’s what I mostly like to do in the UK.

sai14

In case it’s not obvious, if your IK runs an inflatable seat, like an air bed, the base is much more comfortable when partially inflated. On the other hand I’ve never found a one-piece seat with an inflatable backrest to be comfortable. You need solid support from a backrest, not cushy comfort. I’ve found an Alpacka packraft seat base and a separate SoT backrest (above) work best in terms of comfort, support and lightness, especially when combined with a solid footrest tube. More here and the full story on seats here.

And S is for sailing – my inconclusive experiences here, though I’ve not given up yet.

T

fpy165

is for thigh straps. The problem with an IK is that you sit on it like a log in water. You have a seatback to lean on to improve paddling efficiency, as well as footrests (ideally solid tubes (left and below), not mushy inflatable thwarts). But critically you’ll be missing a knee-bracing element to triangulate you with the boat, which hardshellers do with their knees pushed under their top deck. This allows much greater control of the craft in rough water – river or sea – and in particular makes eskimo rolls possible.

While they’ll never replicate the near-direct bracing advantage of a decked hardshell, thigh straps (as found on SoTs), are the next best thing. When you feel your boat is tipping over, a hip flick against a knee brace, combined with a paddle slap or brace, may be enough to keep you upright. Thigh braces add up to more control in rough water and better paddling efficiency too.

ari14

T is also for transportability and touring. An IK makes a great touring craft as it’s so much easier to get to a destination, set up your boat and set off while incurring no extra cargo expenses or knocking someone’s head off in the duty-free shop. I took my packraft and IK to Australia once without going over my baggage allowance.

Another T is for tempering. On a warm day when you inflate your IK on the shore and then put it in the cool water the floor and maybe the sides will cool, losing some pressure and rigidity. With something like a K-Pump (right) it’s easy to top up the half psi that may have been lost to get your IK as rigid as the maker intended. Stiff IKs are fast, efficient, responsive IKs. Or, just adjust for the water cooling effect by over-inflating your IK a little in the first place on chambers with no PRVs. In cool places I ran my Grabner at 0.35 bar – 0.05 over what they recommend. In the warmer Med I’d stick to 0.3 bar.

303U

is for UV. It pays to spray the sunny side of your IK and all your kayaking fabrics with either Aerospace 303 Protectant (right) or the similar ArmorAll product in the US. If nothing else, it’ll make your boat look newer and brighter. It works great for motorbike tyre changing too.

V

az-valve

is for valves. Proper one-way IK valves are the same as those used on commercial whitewater rafts, but may require occasional tightening into the hull fabric with a special tool (left). I’ve never had a valve malfunction but am always careful to replace the valve cap to keep grit out of the mechanism.

Some valves have bayonet fittings like a light bulb; this makes a secure fitment for the air hose and will be needed on high pressure boats, otherwise the push-in hose method on old Gumotexes works surprisingly well. Cheaper IKs (and packrafts) have Boston valves (below left) and really old ones have simple lilo plugs (right). There’s more here.

W

w4wind

is for wind, the enemy of IKs, especially at sea. Depending on ambient temps, F4 (Beaufort Scale, below)) is at the limit of what I’d choose to paddle in. I’ve tried sea kayaking in stronger winds in the tropics with head-on speeds down to 1 mph and the boat barely controllable when blown from behind. In such conditions a light IK with most of its hull above the water was ill-matched with a four times heavier hardshell sea kayak.

IK&P Tip: when you start seeing whitecaps at sea or on a lake, it’s probably getting too windy for an IK or packraft.

f4
ner - 7

W is also for width. The nature of a round sidetubed IK’s hull makes it wider than a hardshell, which affects paddling efficiency and speed. I was out once on a rental Hyside Padillac IK that was over a metre wide and the Neris Smart 2 (left) comes in at 95cm. Such boats are extremely stable, easy to get into and hard to flip over. To the average holidaymaker who doesn’t know a kayak from a canoe, they make whitewater look fun rather than scary. In my experience, many American-branded boats are in this over-wide category. An IK need not be more than 30 inches or 76cm wide. Anything more is more raft than a kayak and my comparison table above now includes a Length Width Index (LWI).

w4white

W is also for whitewater, something that any sub-4-metre IK can manage up to grade 3. That will swamp a non-bailing boat, but if it’s in southern France in summer, you won’t be complaining. There are plenty of vids on youtube showing what IKs and packrafts can manage on whitewater.

X and Y

Submissions invited. Best entry wins a PVC D-ring.

Z

might be for zig-zagging – the motion beginners encounter until they get the knack or try a kayak with a skeg. Also called the windscreen wiper effect. After a while you get the knack.


Pierre Debroutelle’s IK in 1936
Bom-bard

Z is also for Zodiac. originally airship makers, it’s thought Pierre Debroutelle constructed original inflatable kayak. Later on Alain Bombard crossed the Atlantic in a Zodiac RIB drinking only seawater and eating fish. Read about his fascinating story here.

sevy4-99

2 thoughts on “A to Z of Inflatable Kayaks

  1. roland_scarlett (@roland_scarlett)

    Hello there. Thanks for the blog – inspired me to get my new Gumotex Rush 2, which I love. You’re right – having a nice boat inspires you to find interesting places to take it to. Just back from a week long holiday with it on the Norfolk Broads.

    As to, “D is for drying”, I’ve noticed after the week’s holiday a small dot of a sort of green discolouration on the grey inside material of the boat. Any idea what that may be, if there’s anything an IK owner should do if they see that, and whether it is likely to be harmful to the boat overall?

    Thanks again for a great site and all the brilliant research material which led to my purchase.

    Like

    Reply
    1. Chris S Post author

      Glad to hear of another satisfied Gumoteur ;-) Point us to some pics of your R2 in action and a mini-review.
      As for the green discolouration, don’t know and never seen the same. Got a photo?
      Is it on the DS floor which may be a different sort of Nitrilon, or the regular tubed sides? I take it it won’t come off with solvent but anyway, I doubt it’s a worry. Lumps in the DS floor (separated/torn space yarn) or lifted seams elsewhere are bad news, but will take years and years, if ever.

      Like

      Reply

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