Tag Archives: hypalon

Gumotex Seawave: Modifications and Improvements

Updated 2021 for Seawave 2

Seawave main page
MYO Seawave rudder

yalding

Grappling to get the boat out of the muddy Medway river at Yalding one time put a light scrape on the hull. It reminded me that, along with fitting PRVs to the sidetubes, another winter job was to fit a protective strake under the bow where most scraping occurs. Better to get the protection in early while the boat is newish.

straker
ami-poly

A 70 x 15cm Hypalon off-cut (close enough to Nitrilon) was 14 quid on ebay and once trimmed left enough for another strake or two. I had some Polymarine two-part adhesive (below) and glued the strip to the boat’s curved form with the floor inflated, even if that meant working the roller to press it all together was less effective. I then slathered some Seam Seal around the nose of the strake to protect it from unpeeling (less runny Aquaseal would have been better but a Seam Seal tube was open. More on glues here).

2021 Update A strake is a good idea but actually got hardly worn, so on Seawave 2 I just stuck on some Gorilla tape, maybe two layers, in the same place. Easily renewed/removed.

While the boat was filling the hallway and causing a hazard to domestic navigation I also bodged up a better system for the all-important footrest. A bit of inner tube now counter-tensions the footrest from the bow to keep it in position. It means the thing is now fully adjustable across a wide range of positions, can easily be fine-tuned from the water, removes in seconds for boat cleaning/drying and needed no extra fittings glued to the boat. Once great thing about the Seawave is the multitude of attachment points on the floor and sides.

2021 Update On Seawave 2 I just passed an adjustable sling through the tube and clipped it to the sides (left). Much simpler.

sw12

While on the river my aged Mk1 Alpacka U-seat base went flat, split right in the U. This seat is part of a lighter and comfier system I brought over from my Amigo – an improvement on the one-piece Seawave seats. It’s currently unfixed to the boat and the thin nylon must have ripped while yanking it into position on the river after getting back in. Again, I’m trying to avoid gluing extra D-rings to the hull – they’d limit seat base adjustment options anyway.

alpacka-seat

Better then to attach the seat base to the base of the backrest with a couple of zip ties. The whole backrest/seat base can then slide forward and back off the backrest side straps and it all unclips from the boat in less than 3.7 seconds. I glued up the punctured U-seat but it won’t last, so I’ve ordered MkII Alpacka seats (left) from Packrafting Store: €70 delivered for a pair. From Alpacka US the seats cost $25 but their auto-calculated international postage is nuts, let alone tax and VAT issues. These seats have the U filled in like a webbed foot: stronger and less floppy for just ~12g extra weight.

2021 Update. I’m using the same system on Seawave 2; a non-U packraft seatbase and a used backrest off a Bic SoT with a piece of stiff plastic board slotted inside.

I’ve also ditched my old my SoT thigh straps (left). Nicely padded and effective though they were, the brass spring connectors and padding made them feel heavy and bulky at ~720g.

Instead I got some non-padded Anfibio packrafting straps (they’re different now). With my biners they come in at 270g. The delta-straps dangling off the sides are a clever idea, designed to give a more direct pull when rolling a packraft for example. Can’t see myself doing that in any of my boats. Whether you’re rolling or just paddling, in rough water the more direct connection with the boat the better. I’m a big fan of these light but effective straps now. No need for paddling.

Semperit Forelle: the original ‘proper’ IK

In 2017 I bought an old Forelle 2. Read more about the…
…afternoon refurb
Semperit at Sea
Semperit at Sea 2
Semperit Mori
Semperit autopsy

semp

Not for the first time I will boldly speculate that the Austrian-made Semperit Forelle (‘trout’) or maybe the Dolphin before it, was the first serious modern IK, designed in the 1960s from tough hypalon ‘rafting’ fabric. Around the same time Sevylor released the PVC Tahiti watersofa in North America and maybe worldwide. I bet the Tahiti has outsold any Semperit 1000:1. I know which one I’d rather own.

According to my measurements the Forelle 2 is 3.56m long, 70cm wide and weighs 10.5kg + seat. This guy says Semperit were last made in 1983 at which point (or soon after) Grabner (also Austrian) bought the rights.

Grabner Fun kayak

Grabner then got Gumotex, in Braclav just over the border (and behind the Iron Curtain, back then) to produce a cloned Forelle called the Grabner Fun (left), but made from Gumotex’s hypalon-like fabric called Nitrilon. Back in the 1980s I’m sure Commie Nitrilon would have been cheaper and probably as good as DuPont hypalon made in western Europe. The Fun was discontinued (or stock ran out) a few years ago.

Grabner Fun: 365 x 75 cm; weight 12kg; payload 170 kg; pressure 0.2 bar; fabric 1100 dtex Nitrilon

Not being one of their boats, the Fun was undersold by Grabner (notice the table, above). Instead, the similar but longer Holiday range got the fanfare and is still made today with few changes.
Grabner boats are made from a hypalon-like fabric called EPDM which, combined with Grabner’s hot vulcanising method, explains how their boats managed to run 50% more pressure (0.3 bar) than the Fun and other Gumotex IKs at the time. Gael A. paddled an aged Grabner H2 along the Scottish Sea Kayak Trail a couple of years ago. Among others, Incept also used the twin-side beam design to produce a 70-cm wide K40 which is also 70cm longer than the Forelle II, and one of the fastest IKs around.

I would say the obscure and expensive K40 and the more popular but also expensive Austrian Holiday 2 and 3 IKs are modern iterations of the twin side tube Forelle design, with the Holidays (below) right down to the wooden bow clamp (right).

You can occasionally find aged Forelle IIs for around €300 in Germany; a new H2 goes for €1900, while Funs were being discounted for as little as €400 new, but seem much rarer now. I was curious about tracking down a Forelle recently (I succeeded) and below are a few shots I picked up off the web and from some sellers. Apart from the odd repair, the indestructible hypalon fabric stands up well (or does it?) and the seats may well have been improved (Grabner’s still use crude and bend-prone alloy bars).

gumvalve
semperit forelle

Some boats come with a huge wooden rudder which might be replaced by a skeg, but one off-putting aspect are the basic inflation ‘lilo plugs’ (left); no better than an old Gumotex seat. These could easily be cut out and replaced with proper Gumotex valves (right), maybe in a more accessible position, too.
It seems older versions (grey and orange, below) have a half-inch deep keep strip right along the bottom (as well as a rudder fitting) while later ones like the yellow one, do not.
One thing that can’t get avoided is that a Forelle (and a Fun) still run only 0.2 bar pressure. Same as most ordinary Gumos, like the Solar 3 though the stiffer twin side beam hull helps. Modern Grabners run 0.3 bar which makes a big difference. Some newer Gumotex IKs now run 0.25, though that can be pushed to 0.3 bar with care.

Thanks to Gael and OP for extra details. Most pics lifted from ebay sellers.

Overhauling a Grabner H2

by Gael Auffret

Gael’s H2 review here,
Compared with other kayaks here
Solo paddle up the Scottish Sea Kayak Trail: Part 1 Part 2

After more than 12 years my tandem Grabner H2 IK was showing signs of wear all over. The most visible appeared behind the fore half deck where two grommets fed the grab lines (below left). Around those grommets the rubber coating had worn off, showing the bare woven core material of the Hypalon fabric.

I knew Grabner could provide an MRO service as stated on their web site and the French Grabner reseller confirmed he could send my boat to the factory in Austria for a quotation. That came the week later in German, but what didn’t need translating was the substantial figure at the bottom which added up to something like “you’re better off buying a new boat”.
Another major concern was a crack that developed under the aft backrest bracket (middle). This ill-designed bracket has a sharp edge that gets pushed into the skin under the weight of the paddler. After some years of chafing it had worn a small hole that proved difficult to patch reliably.

I must to admit the H2 is not as perfect and tough as I’d claimed so loudly. Encounters with various submerged obstacles and a number of uncontrolled landings had resulted in many scars and scratches all over the hull. I now also own a similar Incept K40 for solo paddles, but as I intended to keep the H2 as a tandem boat, I thought it was time to give it a serious makeover.

Grabner’s attitude to those requiring a more seaworthy kayak than an H2 was get an Explorer or the framed but now discontinued Discovery, but those IKs are way too bulky and heavy (26kg and 29kg respectively) for transportation when shuttling about.

My H2 weighs just 16kg. Plus they are just about the most expensive IKs in the inflatable world (left). I discussed the money issue with the other half of the H2’s crew who happens to also be the purser. She too wanted to keep the H2 and was not as appalled by the cost as I was, so after a short deliberation we decided to proceed.
Three weeks later my local reseller informed me enthusiastically that my H2 was here and beautifully refurbished. Save for the numerous patches it looked like new.

The Grabner folks had done a great job; even the foredeck grommets had been neatly repaired.
All backrest brackets had been replaced with new parts of a much better design. A new pair had been added at my request to enable solo paddling from a central position. Up till then I’d sat in the back of my H2 when solo.
Most cockpit fittings like footrest and D-ring brackets which had started coming loose had been reglued.

There was a keel strip on the bottom as well. Surprisingly the Austrian guys hadn’t paid attention to the colour of the patches (left). While the inside the H2 is yellow, they applied patches in external red. I should have supplied them the yellow patches I’ve got in my repair kit. Anyway, I’m happy the boat is in such great shape again, if not better than before. I can’t claim it’s worth as much money as I’ve spent on it, but I’m sure my H2 will go for another 12 years.

Inflatable kayaks. Part 1: Fabrics and Fabrication

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