Tag Archives: Hypalon repairs

Semperit Mori

sempp3A couple of days after trying out the Semperit I noticed a scratch on the hull bottom (left) so decided to pre-emptively patch that with Bostik sevy4-71782 (less faff than 2-part). It looked like an old scratch which had opened up by reusing the boat.
I reinflated a day or two later, but a few days on noticed the floor was flat. I pumped it up again – air was hissing from a crack in the hypalon coating inside the boat, more or less under the seat (below left; colours enhanced for clarity).
sempoThis seemed a bit odd. The boat hadn’t been over-inflated or left in the baking sun, and there wasn’t any obvious rubbing in the two hours I’d used it, though I suppose this is a high-wear area and an old boat.
I suspected general, age-related delamination or entropic porosity. The outer orange hypalon coat can be rubbed or cut down to the fabric core, as with the hull scratch I’d just repaired. But inside should be an airtight layer of neoprene. No way of checking that without open boat surgery.
To be honest it’s what I half-expected from a 40-year-old IK, which is why I’d kept the refurb to a minimum. I suspect sudden use after many years possible neglect had accelerated its decay. I see the keel-strake is coming away too, as are some other black patches holding the rusting D-rings.
merkelI’ve experienced similar deterioration when buying old vehicles for long trips. They seem like a bargain and had a solid ‘they-don’t-make-’em-like-they-used-to’ reputation in their day. But sempoereviving them, or just asking them to perform as they once did, can lead to a string of failures until it’s just not worth it (left). Much depends how they’ve been maintained over the years. I recall writing in one of my books (or maybe here): “you can’t give your old gran a pair of trainers and expect here to run a marathon without having a heart attack“.
I patched the wear-hole with more 1782, reluctant to waste good two-part Polymarine. Pumped up and filled it with water: all good, but an anomalous perforation somewhere else can’t be ruled out.
That’s another thing I’ve learned with old cars and bikes: you replace the clapped out engine then the clutch goes; you replace the clutch and the gearbox goes; you replace the gearbox and so on… The strain of refurbishment gets passed to the weakest point. An IK will get you to shore on two chambers, especially if its just the floor that’s gone. I had that once with the Incept. Out with your pals on a warm summertime river, that’s no drama. Elsewhere, alone with the wind picking up; not so trivial.

There’s a such a thing as hypalon paint (right) to revive old boats, but that goes for at least £100 a litre – possibly worthwhile on your cherished RIB; not on this old IK. If the hypalon is delaminating from the woven nylon core, paint won’t save it. You’ve got to know when to call it a day, and that day may have come for the old trout.

sempsawnA few hours later the floor was soggy – this time it had let go a few inches up from the recent patching – the ‘clutch going after the engine’. Up to then I’d been considering putting it back on ebay with a clear semperit caveat emptor. But then I decided sawing it in half would be more fun. I always wondered what an I-beam floor looks like.
Read the IK autopsy.

Inflatable kayaks: glue and repairs

Updated Summer 2020

See also: Repairing a Gumotex Seawave
MYO D-rings

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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.

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I’ve owned over a dozen inflatable boats and have only had one tiny thorn pinprick in the Inceptage-related fabric perforation on the ancient Semperit and a hole worn through carelessness in my Seawave.

It’s hard to think of anything puncturing my full Nitrilon Gumotex IKs or the old Grabner once on the actual water. What more often happens is some kind of accidental wear or rubbing when not paddling or during transportation, like the trolley wheels which wore a hole in my Seawave, or the windy tree branch which rubbed (but did not puncture) my Grabner (left). I also 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 the right glue to both surfaces, wait, then slap on the patch and press down hard with roller to achieve a long-lasting bond. More below.

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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 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 it from wear, as shown above left (not an actual puncture).

One-part glues
I’ve succeeded in gluing on non-critical D-rings onto Nitrilon Gumotex and EDPM Grabner boats using single-part Aquasure sealant/adhesive. 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.
Their Seam Grip is a runnier version of Aquaseal to get into cracks and seams. 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.

sempoe

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 once went real cheap on ebay.

glue-dring

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. 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 PVC) and at £10 for 100ml was good value. Plus it’s a nitrile rubber/resin-based solution and I’ve found won’t go off and harden in the tube like Aquaseal often does. It’s my favourite, do-it-all, one-part glue

One glue I wouldn’t bother with is whatever Gumotex used (still do?) supply with their repair kits: Chemopren Universal (above 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 years ago and finding it was crap. Back then it may have been me, but I tried to use Chemopren again 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 (above 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 or Aquaseal for field repairs

Two-part glue

ami-poly

For important jobs use much stronger two-part adhesives suited to actually assembling air 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 (left) is much cheaper per ml than Aquaseal or Bostik 1782. In the UK Ribstore and Ribright sell similar stuff (below) 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 as well as repairs to my Nitrilon Seawave, It sticks like shit to a s***el.

sempauto - 11

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 Knipex hydraulic trench pliers and even then, the patch coating pulled away from it’s core (lighter exposed weave below) or the patch remained stuck to the boat and instead pulled off the dead’s boat’s hypalon coating revealing the fabric’s yellowed core or scrim. The two recently glued surfaces could not be separated. They say the mixing of the two components causes a chemical ‘vulcanisation’ and molecular cross-linking which creates a very strong bond. Mixing and applying two-part is a pain, but it works.

semp-glue

Get a good roller

sealey

Single or two-part, once you apply your patch, roll it very hard with something like the classic Baltic-pine handled Sealey TST15 stitch roller (left) aka: tyre repair roller used for innertube and tyre repairs. The knurled metal wheel set in a solid handle applies much greater pressure than a wide plastic roller I used to use, and they’re only about a fiver on ebay. Buy one now so you’re ready.

glu-tyvec

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 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 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.

Good article on how adhesives work

Cleaning solvents

foamdandingblock

Once you’ve done your roughing up (sandpaper or a foam abrasive sanding block, left) 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 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. 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.

toluene

For a travel repair kit a tin of lighter fluid (same as white gas) or nail polish remover (acetone) are easy to buy and handy to pack. Back at home I’ve found MEK (Methyl Ethyl Ketone) 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’ explosive, fyi) for hypalon. On ebay uk it’s the same £9/ltr but they won’t post this stuff around the USA.

Huge tears and bear bites

semp- - 3

If you have a huge gash, as in the folding Klepper’s hull below, 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 below caught a cut-down metal fence stake buried in a 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 left was glued with a 5-inch patch but the 30-year0old IK proved to be totalled.

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