Tag Archives: semperit forelle 2

Semperit Mori

Semperit main page
Read the IK autopsy.


A 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 1782 (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; colours enhanced for clarity).


This 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 scratched down to the fabric core, as with the hull scratch I’d just repaired. But inside should be an airtight layer of neoprene. There’s 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 and expenses to a minimum. I suspect sudden use after many years possible neglect had accelerated decay. I see the keel-strake is coming away too, as are some other black patches holding the rusting D-rings.


I’ve experienced similar deterioration when buying old vehicles for long trips. They seem like a bargain and have a solid ‘they-don’t-make-’em-like-they-used-to’ reputation. But reviving 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 on how they’ve been maintained over the years. I recall writing in one of my books (or maybe on 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. I 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 on to the weakest point, and when that’s repaired, to the next weakest point. An IK will get you to shore on two chambers, especially if it’s 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.

Years later I learned PolyMarine make SealFlex – a latex sealant (right) to revive old inflatables, PVC or plastic. You pour some in each chamber and roll the boat around for a couple of days. It costs £26 posted for 500ml – possibly worthwhile on your cherished RIB; not so sure on this old IK but had I known of it I may have given the old Trout a pint’s dose. After that you’ve got to know when to call it a day, and that day may have come. It might be fine for a guest or a rec river boat, but I don’t do so much of that nor have space for more stuff than I need.


A few hours later the floor was soggy – this time it had let go a few inches up from the recent patching. 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 and educational. I always wondered what exactly an I-beam floor looks like. More here.

Semperit at sea – 2

Semperit main page


With an inexpensive Sevylor barrel pump I was able to get the repaired Semperit up to a good pressure. Ten days passed while i finished my current project, during which time the boat lost no air that I could feel. Over the same period the Seawave was a little soggy all round, as you’d expect with PRVs purging with changing temps. I keep the boats alongside the shadiest north side of the house, but this far north the early morning- and late evening sun still lights it up. In fact, looking at the graphic, above, it’s amazing just how far north the sun comes and goes at this time of year, a month from the solstice. Work out your own angles and azimuths.


Back to the Sempeerit. With the desk finally cleared, conditions were as good as they ever get up here: hot, sunny and virtually windless – a triple meteorological miracle.
I decided to nip over to Horse Island from Badenscallie (bottom of the map, above right), still assuming the boat might track poorly and feel saggy. As it was, the Forelle felt much better – as good as you can expect of a 3-psi IK. With just the slight 2 o’clock head-breeze, I was reminded of the technique for skeg-free paddling: simply pull gently to stay straight. You go a bit slower but in the near-calm conditions it worked, with the odd double pull to bring things back on line.


With spring tide flows peaking, I was too late to pass through the channel between Horse and Meall nan Gabhar, so I clambered up a hill. Looking south to Eilean Dubh and the outer Summers (below), I could have done the full tour in the Seawave. You only get a couple of days a year like this.


Back at the boat, it seemed a shame just to paddle the mile back to Badenscallie now that it had proven itself. So I set off north around Rubha Dunan. With the ring of mountains from the Torridans (below) up to the Assynt, what an amazing day to be out in a kayak.


On the way back I managed a quick selfie to assess the sag and have to say that’s pretty good considering I’m nine times the weight of the 3.5-m boat. In a ruined croft on Horse I’d spotted a plank bench and thought about pinching it to level out the boat (by sitting on the plank),  but in calm waters the fully pumped up Semperit was holding up fine.


It wasn’t all rosy: my old packraft seatpad was leaking from the stem base, and with my reluctance to lean back on the basic rope backrest, I couldn’t relax fully. I ended up sitting on my water shoes (a new pair of Teva Omniums) which gave me nearly enough butt-over-heel elevation for good paddling efficiency. The rope could work well enough, but I don’t want to stress the ageing Forelle’s puny seat-mounts. What the boat really needs are a couple of bomb-proof D-rings on top of the sides to take the backrest strain in line (like I did on my old Amigo – left), but as I’ll be selling the boat, I’ll let the new owner decide what sort of seats they want. Like all IKs, with a higher seat or a small crate, the Forelle could easily be used as a canoe. I know a lot of people like them.


According to the map, Port Mhaire is where I landed. From here a new track led inland to the cafe at Polglass where I dumped the boat under some shady trees and walked back to Badenscallie.

With proper seat support and perhaps an articulated skeg pivoting off the existing rudder mounts, the Semperit would make a nifty boat for calm inshore and lochs, and rivers. But in the Seawave and my Alpacka Yak, I’ve got all the boats I need. It was fun to do up and try out the Semperit, probably the first serious IK from which twin side-tubers like most Grabners, the Incept and Gumotex Seaker can all trace their roots.


Semperum Mare (Semperit at Sea)

Semperit Forelle main page

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No doubt about it; since flogging my much-used Sunny in 2011, followed by a flawed experiment with a Feathecraft Java, I’ve become spoiled by high-pressure IKs like my fast Incept K40 (based on the Forelle’s design), the brick-hard but slower Grabner Amigo and my current lightly modified Seawave. Just 25-60% more pressure makes all the difference, especially once the boat gets usefully long.

I only had my K-Pump Mini to inflate the Forelle after its repair and mods. I’d hand-pumped it up as hard as I dared but was probably a bit too cautious to not over-stress the old trout. Getting in I was reminded of that uninspiring slackrafty squidginess. I should have topped it up after putting in the cold water, but anyway there’s no easy way to accurately check the pressure off lilo plugs (I tried jury-rigging my manometer). Presumably in the 70s the idea of using tough, one-way rafting valves on IKs hadn’t been thought of yet.

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In this under-inflated state and with a slight breeze, tracking away from a headwind was tricky, though I knew that new boats require a quickly acquired knack. As expected, the crumpled keel strip didn’t really do much, perhaps that’s why the Forelle 2 came with a rudder mount. As you can see there’s some taco-ing (folding) going on below me – and this was before lunch!  Without a skeg or a rudder such sagging won’t help good tracking either.


My over-pressure caution was understandable, but thinking it over, I decided the Semp was under-inflated. What this boat needed was a better pump. A couple of days later a £10 Sevylor stirrup pump turned up (I left my super-duper Bravo kite pump down south) and I whacked in what felt like Sunny pressures. With the position of the lilo tubes tucked under the stern cover, and the need to yank off the hose adaptor while pinching the tube to stop air escaping, and jam in the lilo plug, it’s a bit awkward. These plugs really do grip/seal well.

That’s another great thing with running calibrated PRVs on all chambers: you just pump away until they hiss and the boat is correctly inflated while being protected from over-pressure. No need for manometer faffing.

Semperit at sea 2

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Semperit Forelle 2; afternoon refurb’


Here in the Summer Isles the reliable May sunny spell is about to end. It’s been great for solar panels with strong afternoon easterlies, not so good for day-long IK-ing. Suilven mountain even caught fire. Yesterday, before it picked up we nipped out in the Seawave to Eilean Fada Beag (below) and listened to the birds. By the afternoon it was blowing hard.

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High time to patch up my latest IK: an old Semperit Forelle 2 I picked up in Cornwall. The boat was sold with some classic paddles which went straight in the bin, as well as a big tear in the side (right). Plan is to patch that hole, then see if it still holds air.

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Semperit is an Austrian tyre manufacturer who’s still in business. Afaik, their IKs were a bit of a short-lived rubbery diversion in the 1960s. If my 40-year-old boat has no other more awkward leaks, I’ll rig it up and take it for a spin. But first, I scrubbed off a couple of decades of crud and let it dry.

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I wondered about sewing up that L-tear before patching it – the Forelle’s hypalon seems pretty thin, but decided to just slap on a 5-incher. I’ve glued on loads of accessory patches but have never actually had to repair a hole in a hypalon IK in all these years. So I took note of the NRS repair video here: rough up hole and patch: wipe clean with solvent; apply two coats of glue and when knuckle dry apply the patch and roller the living daylights out of it.

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Watching that vid, I saw they used a much better tool for pressing down patches; an ash-handled Sealey TST15 tyre patch roller, unless I’m very much mistaken. The knurled metal wheel embedded in the wooden handle can lay down much more pressure than the wide plastic lino roller I’ve been using.
Just before I did that, it occurred to me stray glue may squeeze through the tear and glue the insides together. Don’t want that nein danke so, with no better ideas, I stuck a bit of paper in there. Seems to have worked.

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With glue left over, I thought I may as well stick on couple of floor patches for a seat base and a footrest tube. As these are non-critical fittings I used any old D-rings I had: a woven nylon one and probably a PVC. I’ve glued PVC to hypalon before for other fittings.

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With them in place I couldn’t resist rigging up the old Trout with a rope-and-pipe-lagging backrest, an old Alpacka packraft seatbase; a drainpipe footrest tube and a lead. All stuff I happened to have in my IK box of bits or found in the barn among the rat droppings. I jury-rigged the K-Pump for nozzeling but haven’t pumped it right up to 2psi as I’m letting that big patch cure for a bit.

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Looking round the repaired boat I see it has rudder mounts; not sure I’ll need one on a 3.56m boat. There are six D-rings on top of the double side tubes but they don’t look like they’ll take the backwards strain of a fabric backrest  Forelles came with wooden backrest bars, (like Grabners who took over Semperit) and which I’ve found prone to bending when used with a firm footrest tube.

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There’s also a squished up full-length keel strip along the bottom. If it works for tracking it will be nice not to have the usual skeg-grounding aggro in shallows or on land. But maybe that keel will slow down turning which is why they have the rudder attachment? We shall see. With twin side tubes the Forelle is just 70cm wide – that’s <28″. But with a thin floor and me sat low in the high sides I’m sure it will be stable enough.
Gumotex still use them for their seats, but the ‘lilo plugs‘ on the three chambers are a bit of a faff for getting a good charge of air.

If the Semp proves viable, I may replace them with proper IK valves. Or I may just leave them as they are. Three £15 Gumotex valves + a £20 PRV will cost the same as the boat, and the lilo plugs can be regarded as their own ‘total loss’ PRVs – when the boat gets too hot they pop! And anyway, there’s no room to fit a big IK valve in the floor as the tubes are too close together. Knock-off Halkey valves go for 7 quid; I might stick a couple in the sides and leave the lilo plug in the floor.


I put it back in the barn with my other restoration project for a couple of days. When I came back it was limp but not draped over that cabinet like a wet pizza. I pumped up and it stayed firm enough, though I’ve forgotten how mushy an 0.2 bar IK feels. It reminds me why I seriously took the idea of trying to increase the rigidity of my old Sunny before getting other IKs. At the beach I filled it with water and stones – no obvious leaks, (or so I thought). A testament to 40-year-old hypalon and glue.

Have to say too, once pumped up, for an IK the old trout is not bad looking. I think the discreet upsweep of the bow, that plywood ice breaker and slender twin tubes make it look a lot less of a bloat than some. Sea trials to follow.

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