Updated January 2018
It’s understandable to worry that something like an inflatable boat is a bit of a liability when out in the middle of a deep lake, hairing down some shallow white-water or far out to sea. This is especially pertinent if your only experience is a beach toy made of a thin and stretchy PVC film.
I’ve owned over a dozen inflatable boats and have only had one tiny thorn pinprick in the Incept and probably age-related fabric perforation on the ancient Semperit. It’s hard to think of anything puncturing my full Nitrilon Gumotex IKs or the old Grabner. I snagged my packraft’s uninflated floor on submerged concrete once, and added protection to the outside and padding on the inside to stop that happening again. I’ve also travelled with cheap slackrafts that have got ruined within minutes and punctured every other day. You do get what you pay for. So when it comes to glue I’ve learned that preparation and application are vital to getting a good repair: rough it up; wipe it down with solvent, apply adhesive to both surfaces, wait, then slap on the patch and press down hard with roller to achieve a long-lasting bond. More below
Is your boat plastic or rubber?
As explained here, broadly speaking IKs are made of either rubber- or PVC-coated fabrics. Rubber-based Hypalon, EDPM or Nitrilon is most often used with the tubeless construction method. On a boat like this, rough up the surface, clean off with solvent (see below), apply the right glue and a same-material patch, all which needs to be done well as the patch is vulnerable on the outside. Or, you can just dab some Aquaseal directly onto a small hole in the hull to protect a patch of wear, as shown above left (not an actual puncture).
I’ve succeeded in gluing on non-critical D-rings onto Nitrilon Gumotex and EDPM Grabner boats using single-part Aquasure sealant. Allow it to become touch-dry on both surfaces. Allowing Aquaseal to half-cure in air and then sticking together and letting it ‘seal’ to itself is a way of bonding anything – even non-compatible rubber-based Nitrilon to PVC, as I did here.
It’s worth noting that McNetts Aquaseal / Aquasure (same thing sold in different territories) calls itself a waterproofing sealant not an adhesive. Their Seam Grip is a runnier version of Aquaseal to get into cracks. Though I’ve not tried it yet, British-made Stormsure is the same thing. In the UK you can buy Aqausure in 28g tubes from £6, or 250g for around £24. Unless you have a lot to glue/seal jobs, be wary of saving money with the big, 250-g tube; give it a chance and it’ll split and harden before you get to use it all, even if it’s effectively over half price.
The other one-part glue I used on my PU/PVC Incept IK, Slackrafts and used recently on an old hypalon Semperit is Bostik 1782, not least because it was originally going real cheap on ebay. I can’t say it worked that well on my Incept; two-part adhesive is always better. Even on the slackraft the Bostik softened and shrivelled the thin PVC (right). But on non-critical applications (D-rings and none-huge tears) 1782 seems to work well on hypalon (rubbery hypalon is always easier to glue than plastic) and at £10 for 100ml is good value. Plus it’s a nitrile rubber/resin based solution and I’ve found won’t got off and harden in the tube like Aquaseal often does. It’s become my favourite, do-it-all, one-part glue.
I have to say the one-part rubber glue supplied with my Gumotex and Grabner IKs would be a last resort – they look like something from a bicycle repair kit. I’d sooner use two-part, but have a feeling that rubber-based IKs are easier to glue well than stiffer and slipperier PVC/PU. Much depends on what you’re gluing – a simple patch repair or a D-ring that may be under strain.
One glue I wouldn’t bother with is whatever Gumotex used to send you with their repair kits: Chemopren Universal (left). It looks like the brown rubber solution you’d use on a bicycle inner tube. I remember trying to use it on my old Gumotex Sunny and finding it was crap. Back then it may have been me, but I tried to use Chemopren recently on my hypalon Semperit and it wouldn’t even adhere to a roughed up, MEK’d surface! To be fair it might have been many years old, but so are my other glues.
Actually what came with my Seawave in 2014 is a small tube of ElaStick (right). But it looks like a generic polyurethane do-it-all glue. It remains unused with the boat and probably will stay that way until it goes off. I’d sooner rely on Nirtile-based 1782 for field repairs.
For important jobs better to use much stronger two-part adhesives suited to actually assembling rubber or PVC boats as well as making more permanent fittings and bomb-proof repairs.
At about £15 posted for a 250-mil tin, Polymarine 2990 Hypalon adhesive (right) is much cheaper per ml than Aquaseal or Bostik 1782. In the UK Ribstore and Ribright (right) sell similar stuff – just make sure you buy for Hypalon or PVC. I’ve used it to glue D-rings onto my Grabner (more here), floor patches to my Alpacka, latex socks to my dry trousers and patches to my Nitrilon Seawave, It sticks like shit to a s***el.
In 2017 when I dismembered an old IK, I was easily able to pull off recent patches glued on with Bostik by hand. But I could only pull off Polymarined patches with a pair of pliers and even then, the patch separated from it’s own bonded coating, or pulled off the dead’s boat’s hypalon coating (above). The two glued surfaces could not be separated easily. That’s how strong two-part glue is. The mixing and correct application of the two components causes a chemical ‘vulcanisation’ and molecular cross-linking which makes a very strong bond. Mixing and applying two-part is a pain, but it works.
Get a good roller
Single or two-part, once you apply your patch down, roll it very hard with either a seam roller (right; like this one for £2). Or a much better tool like a Sealey TST15 stitch roller – left – used for inner-tube and tyre repairs. The knurled metal wheel metal applies much greater pressure than a plastic roller and they’re only a fiver on ebay. Good video below: learn from the experts.
Bladder boat and packraft repairs
With smooth-skinned Alpacka packrafts, they recommend two-inch wide Tyvec adhesive tape produced by DuPont. Just peel off the back and apply a section on to pricks or small tears once the surface has been cleaned and dried. No need for roughing up, but a quick wipe with solvent won’t do any harm. Larger tears can be sewn then taped. Tyvec will work on urethane IK bladders and extra tacky duct tape or gorilla tape will do too, but is unlikely to remain impermeable once immersed for a while.
Aire-style bladder boat repairs are actually easy. According to Aire’s youtube vid, you unzip the hull shell, slap on a bit of Tyvec on the split, tape up the inner side of the hull shell gash too to keep out grit, reflate and off you go. You can glue up in the usual way later, if necessary. I had the feeling that on my Feathercraft Java the urethane-coated sponsons made of thin ripstop nylon fabric (like tent flysheet material) couldn’t have been so easily or securely repaired with tape. In fact it would be difficult to bond anything well to the slippery nylon fabric compared to smooth urethane plastic or hypalon-like surfaces, but perhaps once inflated the seal would have been fine.
Once you’ve done your roughing up (sand paper or a foam sanding block, right) you need to clean off the residue as well as any oil or grease present. Anything will do in a pinch; alcohol and spirits, after-shave or perfume, nail polish remover (acetone), lighter fluid, white gas or petrol of course, but not oilier diesel, aviation fuel or Nivea for Men. Bleaching agents aren’t the same thing, but might work. In the end just use water to remove the dusty, post-roughing residue, and on a cold day it can help to warm up the damaged surface to cure the glue more quickly.
For a travel repair kit a tin of lighter fluid (same as white gas? above left) or nail polish remover (acetone) are easy to buy and handy to pack. Back at home I’ve found MEK (Methyl Ethyl Ketone; white bottle, above left) is inexpensive at £9/ltr and hideously effective.
Acetone is even cheaper and perhaps less extreme – all we’re really talking about is cleaning off any grease and the dust after sanding.
They say MEK is for PVC boats rather than Hypalon, but on a thin plastic slackraft the PVC will shrivel up before your eyes once MEK’d. Even on rubber-based coatings use MEK or similar toluene sparingly – expect some colour to come away on the cloth and the coating to soften at bit – good for adhesion. Note the NRS video above specifically recommends toluene (the second ‘T’ in ‘TNT, fyi’) for hypalon. On ebay uk it’s the same £9/ltr but they won’t post this stuff in the USA.
Big tears and bear bites
If you have a huge gash, as in the folding Klepper’s hull on the left, sewing is the only way to contain the tear when applied to an IK. Then apply a huge patch with adhesive, as normal. The boat on the left caught a cut-down metal fence stake buried in the shallow river bed and was actually sent back to Klepper for professional repair. It’s tempting to think an IK’s pressurised hull would have skimmed over the stake rather than snagged it. The smaller 1-inch L-tear on the right was glued with a 5-inch patch.