Category Archives: Tech

Packboat Fabrics & Construction

Inflatable Kakak autopsy

Semperit main page

Performing my cutting-a-kayak-in-half trick gave me a long overdue chance to see exactly how they’re put together, as well as other stuff, like why it was failing and how well certain glues stuck.

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hypalon fabric

The neoprene inside
I used to assume it was the same coloured coating inside the boat as out; it’s just simpler. But of course, the diagram left is clear: what’s outside and what’s inside an IK hull is not the same stuff. There’s no need to waste UV-resistant hypalon coating (or colouring or that matter) inside the boat’s benighted chambers. All it needs to be is the same durable and airtight coating, and neoprene – the brown rubber-like coating left – does that fine.
I bet I’m not the only one to mistake ‘neoprene‘ as simply that closed-cell sponge used in wetsuits or laptop sleeves. In its solid form it’s a durable synthetic rubber, but I presume lacks the full-on UV resistance of hypalon which DuPont invented shortly after.

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I-beam floor
As mentioned here, an inflated vessel will seek equilibrium by attaining a rotund form, be it tube or sphere. A flat inflated plane such as an airbed or an IK floor needs to be a series of parallel tubes – or just a non-inflated sheet, like packraft and white-water raft floors. It also works the other way with bed mattresses. The springs and foam must be constrained by straps or whatever to keep the spring mattress flat.
So this is an IK I-beam floor (left): probably the same tough core of nylon or polyester scrim, but without the impermeable hypalon and neoprene coatings of the exterior panels.
Note the pre-folds or creases to help the Semperit pack flat. I imagine modern IKs do the same, but it all explains the necessary attention to detail which makes ‘tubeless’ IKs like this so labour intensive, compared to ‘bladder’ designs like Aire.

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Twin side-tube IKs like this Forelle, the Incept and Grabner Holidays, have two smaller tubes one on top of the other, rather than one fat side tube like my Seawave (left, red) or Amigo. It gives the same buoyancy, more freeboard (above water height), a slimmer profile (more speed) or make more volume inside (easier packing). The red Seawave on the left is 82cm wide; the Semperit is 72. It makes the boat look a whole lot better too and overall because it’s also no less stable, I’d say it’s the best design for an IK, but it also needs I-beam sections to constrain the two side tubes.

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I can’t say I could suck air through the scrim easily, but I’m pretty sure it’s porous – I didn’t find any transfer holes to allow air to flow between adjacent tubes – they might be a weak point.
When an IK like this is over-inflated (or left in the sun) and is unable to purge through PRVs (none on the Semperit), you imagine it’s this scrim which either tears apart, most probably at the T-join where it’s glued to the neoprene. I tried tearing sections of scrim by hand;  impossible where it was uncut, but as soon as you nick it with a knife it would tear quite easily, like thin cotton cloth. This fabric was at least 40-years-old and had one or two patches of mildew, but was still tough and the whole assembly of the boat has held together amazingly well over the years.

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Where mine failed
Inspecting the fatal second leak alongside the earlier repair, it seemed air was pushing through where two sections of I-beam scrim butted against each other. Perhaps the old coatings stretched differentially here or were just worn out.  It did look like the hypalon was simply flaking away.
I could have fixed that leak but, as mentioned, another would probably pop up whack-a-mole style somewhere else, quite possible while at sea in either my- or a new owner’s hands.

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Glue test
I repaired the big original ‘L’ tear with a 5″ round patch of hypalon and two-part glue (above and left). I then patched a down-to-the-scrim scratch under the hull with one-part Bostik 1782 (left). I used the same glue to repair the initial new leak inside (bubbling water, above).

Although I’m pretty sure they’d have lasted, I could easily pull off the Bostik patches by hand. Pulling off the big round Polymarine’d patch was another matter. It just so happened I’d sawn through the round patch but, only once I got some pliers under a lip (above left) was I able to separate it from the hull. As you can see in the big image below, either the ancient orange hypalon coating of the IK, or the newer red hypalon of the patch separated from their respective nylon cores – the glue’s bond was stronger than the actual hypalon coatings, new or old.

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I get a bit lazy about having to faff about with two-part glue, and I also wonder if I ever guestimating the 25:1 ratio correctly. But as you can see, this stuff sticks. If you absolutely, positively want it to stay stuck, use two-part adhesives.
I still don’t know if the second part curing agent merely speeds up the drying process, or is chemically integral to creating the very strong bond. I’d think it’s the latter, otherwise why bother.

There’s more about glues and repairs here.

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Other stuff
The distinctive marine plywood bow has lasted fine – no warping at all and the rivets are still intact.
It may have been an early design solution to easily joining the three sections of the hull in a nice sharp point, though they managed that join easily enough at the back. Maybe it was as much for protection and a frontal tracking aid.
I now have enough hypalon patches and D-rings to see me out. Other images from the autopsy below.

Semperit Mori

Semperit main page
Read the IK autopsy.

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sempp3

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).

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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.

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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“.

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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.

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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.

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.

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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’

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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.

eileanfada
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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.

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semptest

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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Does your inflatable kayak need a deck?

Whatever you read here, as much as anything, choosing an IK with a deck is more about personal preference than function.

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Most inflatable kayaks are like canoes and have no deck. A few like the Gumotex Framura and Swing, or the Grabner Explorer and Decathlon X500 and some Advanced Elements have fixed decks. Others like the Kokopelli Moki or Gumotex Seawave (flashing above) have zip-back or velcro decks.

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Above, a yellow Incept K40 with a zip-back deck, the one time I used it like that. And later, when I bought my Seawave (above left and below) I got the optional fully removable deck thinking it might be handy. I tried it once, took some pictures, never used it again and eventually sold it.

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decko

Other optional deck IKers have said the same: nice to have the option but never actually use it. Both these boats needed fibreglass or alloy spars to support the deck from below and keep it convex to make water run off. It all just adds to more stuff and set-up time.

For me, one of the big attractions of an open IK is it’s so much easier to hop in and out – even from deep water you can easily crawl back abroad which makes it safer. It’s easier to pack or unload the boat (below), as well as dry, clean or work on it.
Any touring luggage will surely be in dry bags anyway and better touring IKs have plenty of attachment points. Best of all there’s no need to faff about with spray skirts and cags to match, and I find it’s so much more agreeable to paddle in the open air and not feel hemmed in. If it’s cold or inclement, I wear a drysuit.

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If you come from hardshell or folding kayaks you might think a deck’s a good idea, but length-for-length hardshells are heavier, less stable and less buoyant than IKs. All that means they slice through waves better and sit much lower in the water so need to allow water to wash over the decks. Also, with a hardshell, knee blocks on the underside of the front deck are crucial in the way the paddler interacts with their boat, creating a solid connection for bracing or pivoting against the swell. For better or worse, raft-like IKs are wider and less tippy. Using thigh braces and a solid footrest (below) is about as close as it gets to improving that ‘sat on a log’ IK feeling; you can’t realistically brace your knees under an IK’s fabric deck.

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bilge

IKs sit higher in the water than a hardshell and swamping only occurs in rough seas or white water, especially in less stiff, low-pressure boats, as I found with my Sunny in Western Australia (below). Rough seas aren’t really suited to IKs, at least not alone, and full-on white-water IKs like the Gumotex Safari, Hyside Padillac or the NRS MaverIK have self-bailing floors so what comes over the sides drains away. But even an unbailing IK will still float when full of water (as I also found in WA), so a bailing pump (left) or more simply, a sawn-off plastic bottle scoop (left) are handy things to carry if out at sea for a while.

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The ability to roll is an important skill if using a hardshell in rough water, but you’ll need taut thigh straps and quite a hip flick to roll a typically wider IK, with or without a deck. In an IK, if you capsize you just fall out then flip the boat back over if necessary and crawl back on. With a fixed deck IK that becomes much more awkward (below), just as it is in a hardshell without help, as we found one wet weekend. Solo, a paddle float is essential. Without one I couldn’t do it – and that was practicing in nice calm conditions (below). In dire straits I’d have unzipped the K40’s deck to get back in.
About the only thing I do miss with a deck is somewhere handy to mount nav aids, cameras and other useful stuff in front of you. I get round that with a pfd with pockets and Peli box or a waterproof packbag between my knees.

k40caps

Seawave Rudder MkII tested

Gumotex Seawave main page

Rudder rationale discussed
Gumotex’s 2016 factory version
Making the prototype rudder
Testing the prototype

Update 2019:
I’ve not used my MYO rudder since I made it in 2016. Partly because I’ve only done day trips predicated on nice weather, but also it’s all just more faff and clutter, not least the lines and footboard. As explained earlier, for multi-day trips where you must deal with the winds you’re given, a rudder is a good idea. But even then, you only notice your relative lack of speed (due to sidewind paddling correction) alongside others. Alone, you’re as fast as you are [grasshopper].
Rudders are not primarily about steering or tracking as they are on powered boats; in a kayak they’re about enabling an efficient, balanced paddling effort on both arms by compensating for the boat’s deflection from side winds. In a way the simple stock skeg-shifter (left) will do as well with much less clutter and weight. Or, use the MYP rudder (below), but locked-out as a lifting skeg in place of the Gumotex skeg for shallows and beach parking. That is handy to avoid stressing the stock skeg, especially when the boat is loaded. 

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mulamap

While waiting for rudder bits to turn up, we went out for an evening paddle round Eilean Mullagrach. It was pretty calm but at no point did I think, ‘Darn, I wish I had a rudder’. When it came to turning corners we just paddled hard or dragged a blade and round we came.
But the Seawave rudder project carries on like a supertanker with a jammed… rudder, if for no other reason than it’s fun to experiment and a rudder can also work as an articulated skeg when locked out – something I may look into when it’s all done.

rudderdyl


Ironing out the flaws with the prototype added up to attaching it more securely at the back and making the pedal board out of something more responsive and durable. By coincidence, all these components can be sawn from a single piece of 450 x 300 x 12mm LDPE chopping board (left) which costs from £8 on eBay in a range of colours. This is 50% thicker than the smaller board I used on the prototype plate so doesn’t need doubling up and gluing to make it rigid.

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At the back I  slimmed the rudder plate right down to a simple strip of 65mm x 450mm, glued a block on the end to better support the gudgeon swivel pivot sleeve and added the crucial second fixing under the portaging handle (above left). I also added a triangularish screw plate underneath (left, with red cord) so it all sits snug in the stern. With the hardware and saddle strap that now adds up to 306g (the rudder unit weighs 450g with its running lines). Even though it’s slimmer than the proto plate, it weighs about the same because it’s now 12 mil. But looks a whole lot neater.

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The pedal board is from the same slab but uses stainless hinges, not zip ties. I’m reminded, you’re constantly making small adjustments as you paddle so pedals need to be as taut and responsive as possible. Once I’d trimmed the board and pedals a bit (left), with hinges it came in at 660g.
The board and maybe the pedals could have been made from 8mm if there was some to spare – but an 8mm board wants to be ~450mm wide to sit snugly in the boat’s side channels. Like the rudder, the pedal board will be subject to strong forces in heavy seas so also needs to be solidly jammed in. Meanwhile, I noticed the floor-laminate prototype  board (right) gained nearly 15% in weight after getting wet – a sign it won’t last long. Still, it made a good template.

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I do wonder if something like the Grabner rudder pedal bar (left, similar to Gael’s old H2) would be much lighter, as solid and as effective as my board. It costs €70 plus €30 for a pair of Zoelzer pedals.
I can’t really see how I could replicate that alloy footrest bar – out of copper tube filled with resin perhaps (like this motorbike rack)? It’s held securely in place without fittings by being jammed in the channel cavity between the floor and the sides (like my board), but a check with Gael advised me against it. As it happened, I’d pretty much decided the same mid-test run (below). A sliding ally bar plus seawater isn’t a great combination and might bend or break, or the pedals snap. I know the ally backrest bar on my Amigo wasn’t up to it and Gael’s backrest broke (though it was ancient). My plastic version may weigh double but should be solid. Interestingly, just as a bag of clam cleats turned up to make a quicker way of fine-tuning the rudder pedal lines from the cockpit, I see left that Grabner use them – a good sign.

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The weather here’s about to crack and then we’re moving south, so in a rush I took the revised rudder plate out for a test with the creaky waterlogged pedal board. Heading towards Horse Island tidal passage, I didn’t need a weatherman to know which way the wind blew: from the WNW at about 12mph.

pedalo

Initially, the boat needed constant small corrections to maintain a course, and there was some stiction, hopefully down to the zip ties on the soggy pedal board. I tried a few tight turns and marvelled at the control and how sharply the boat swung round like a pedalo. The rudder plate is now as rock solid as anything fitted to an IK can be. Again, I consciously tried not to correct with my arms, just my feet, which were twitching regularly.

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At Horse Island I was way too early to run the passage, but as it was probably my last paddle here till next year, I decided to head for Badentarbet. Turning north, closer into the wind the micro corrections were no longer needed and the boat ran as if on a skeg, but without arm corrections. I’m pretty sure paddling 20–30° off the wind would have required arm steering, but I just hacked away towards Rubha Dunan on the mainland as the wind increased. When I tried a bit of downwinding protracted rudder juggling was needed to keep the back-end in line.

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I passed through a channel on the headland and the NW wind got steadily stronger so crossing the bay to the beach seemed to take ages of effort. By now the small corrections I’d been making were no longer necessary, perhaps something had bedded in, the knots had tightened up or like riding a bike I’d just got the knack of minimal rudder movement to keep the boat on track. But upwind paddling is comparatively easy so I tried across the wind, now running over 15mph, and a bit more downwinding which gave me that unsettling Ningaloo feeling. This must be the weak point of a buoyant, windprone IK (especially when unloaded), and maybe all kayaks and canoes too. The chop was only a foot high but were there a swell of a metre or more, the rudder would be briefly lifting and the stern sliding. I wonder if in such conditions a combination of rudder and skeg (which is always submerged) might be a way of limiting weathercocking? Or perhaps just more practice is required. There’s also another solution that might arrive here in time to try out.

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As I neared the beach the wind was hard in my face but I realised I was actually on good form, unlike on the Tanera run with the prototype. So I hammered away with all I had until my strake hissed onto the sands. Paddling hard is all helped by my brilliant, bent-shaft Werner Camano paddle, no less than ten years old this summer. It still clips together with a satisfyingly ‘clunk’ and has very little play. If it ever got lost or abducted by aliens I’d buy another without hesitation. I was glad I’d got stuck into a longer test run than planned, and am now confident my MYO Seawave rudder is in the ballpark. Hopefully, the new pedal board will complete the job. 

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  • Total weight: 300g rudder plate + 450g rudder + 660g pedal board + ~100g rigging = 1.51kg (3.3lbs), or < 10% of the boat’s weight
  • Total cost MkII version: £20 rudder + £15 rigging + £8 LDPE board + £10  hinges + £2 fittings = £55
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For about £200 posted I could have installed a 2016 Seawave rudder kit, but from all the images I could find at the time it was unclear exactly how it secured at the back – there must be their version of an unseen triangular underplate, but even then it’s still a stressed-out single point attachment. My additional under-handle fixture eliminates pivoting.

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And the plywood Gumotex footboard (right) appears to sit loose and seemingly will also pivot on that single strap. Production versions may differ and let’s not forget that adding all this complexity also adds a risk of breakage or damage. The simplest solution is usually the best, but the 160-g skeg will always be clipped in the boat as a back-up and a Seawave is controllable (if much slower) with no tracking aids at all. It’s worth remembering: a rudder isn’t about day-to-day tracking, it’s about maintaining a course when the boat gets pushed about in stronger winds. In such conditions a skeg is essential and a rudder is an improvement, as explained here.

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On the beach, prior to lugging the boat over seaweed-clad boulders, it took only 30 seconds to unclip the rudder mechanism from the plate to pre-empt stumbling and damaging it. Since then I changed the rudder plate mounts with tool-free knobs and an eyelet (left). When rolling the boat up it was best to pivot the rudder plate around the drain hole 90° to pack better.

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Inexpensive packboat rescue and survival aids

knifewhistle

The other day while leaning over aboard a salmon pen platform, my cherished six-year-old Benchmade Griptilian slipped out of the pfd and into the briny depths. We ummed and ahhed about diving down to retrieve it, but I’m told these pens are 20-metres deep and can hold no less than 80,000 salmon.
It was a bitter loss, all the worse when I saw what a replacement cost new. Long story short I replaced it with a similarly anti-stealth orange PBK EMT Rescue Knife from this place on sale for just four quid. Like they say “you won’t worry too much if you drop it off your lifeboat and [it] sinks into the depths.” No I won’t.

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aqua

At 150g it’s a bit heavy but locks out with one of those cheap ‘liner’ locks and has a window smashing stud, should I ever find myself in the nightmarish scenario of being trapped in a sealed aquarium. You also get a pocket clip plus a handy line cutter – a good idea when your packboat begins to acquire yards of lines and straps all adding up to an entrapment risk when expelled from the boat. As it is, I’ve long had a quick-grab Benchmade #8 Rescue Hook permanently attached to my main pfd (see below). With no knife-like sharp point, it’s a good thing on an inflatable running 4.8 psi.

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Once you’ve cut yourself free from your boat, the next thing is to alert others of your distress. Gael had a nifty ‘survival’ whistle on our recent Mull trip. This isn’t just any whistle, this is a bonafide survival aid. You also get a thermometre to check on the hypothermia index, a mini magnifying glass for roasting ants, and a compass to help evaluate your drift.
All that for just 99p from China, or under four quid in orange from the UK. The only thing that’s missing is some sort of pea in the whistle body to give it a more punchy warble. I tried shoving a lentil in there, but first go it blew out and temporarily blinded me – which was when the magnifying glass came in handy. Search eBay for “4 in 1 Thermometer Whistle Compass Magnifier Survival” and feel safer out there.

helporwhat

Seawave – Oh Rudder, How Art Thou?

Seawave main page
Skip forward to MkII rudder

ohrudda
snaps

Within hours of finishing my prototype rudder I set about finishing it properly, and after a test run to Tanera, made further improvements, listed below, before trying it again.
The whole set-up wants to be mountable/removable without any tools or knots to untie. I used mini karabiners to attach the various lines but realised snaplinks with a ring are better, as they’re permanently attached so won’t get lost. I recall the fine wire clips on my Incept rudder and after hours of webbery found out they’re called fishing snaps (right). Let me tell you, you can spend a lot of time online trying to figure out if size 00 is bigger than size 8 and still end up buying ones so small you need tweezers to open them. Moving on, some ringed karabiners (black, right) now do the job.

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I only know two knots from my climbing days and still regularly use the Figure of Eight, (right and left) a quick way to put a loop on the end of a line that’s easy to undo. If you want to feed an Fo8 into a fixed ring (like the black krabs, above), just make a loose ‘8’ near the end of the line, then feed the loose end through your ring and follow it back in and around the Fo8 all the way out again. And add a lock knot for good measure.

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Lines shouldn’t be knotted directly to a fixed object, especially if it’s pivoting, but on the rudder’s lifting pulley there’s no room to attached a krab or mini shackle. The lowering pivot has a hole and channel for a nipple (right). I suppose I could track down a short length of appropriate wire cable, but for the moment it’s a job for our good friends, the zip ties. Lovely family. I also moved the rudder lifting knob to the right side: forward to lift (slightly more effort); pulling back to drop seemed intuitive.

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In this pre-optimised form I crossed the two miles to Tanera Mor with a light WSW wind at 2 o clock. First, like a bush pilot, I checked my flaps: up and down, left and right, then started the engine and pushed on the throttles.
Very soon something was wrong. I was having to rudder hard left and the pedals were leaning way forward. I stopped to knot the lines to take up some slack, but still the boat was turning into the wind and the rudder was very slow to respond.

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With a skeg it’s usually the bow that pushes round on a crosswind. Was the new rudder assembly making more windage to push the back around? More stopping to add knots to the pedal lines. I was also reminded that with a rudder you don’t just set it and paddle away, but are constantly making tiny corrections. You probably do the same with your arms and a skeg, but never notice until it gets obvious (the whole point of fitting a rudder). For this reason a rudder wants to be as smooth-running and taut as possible.

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The forecast was cold and northerly, so, over-dressed in a cag and dry pants, all this foot and arm work took it out of me as I resolutely tried not to correct with my arms. It was a relief to arrive at Tanera’s 200-year-old pier. Mooring up, I noticed my rudder plate was dislodged (right), explaining why the pedal tension and tracking had gone awry. It was only when I got back that I noticed I’d fitted my nutted ‘underplate’ upside down and the nut had pulled out. Oh Brother What a Plonker. I locked down the plate with a zip tie and readjusted the pedal lines yet again.

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It was also clear that my scrapheap pedal board was flawed. Heels resting on the board (left) put them two inches higher than normal – not good for paddling efficiency, comfort or pedal actuation; perhaps quite good for neglected muscles. That was easily fixed by turning the board around.

After an  hour exploring this historic corner of the island (more here shortly) I headed back and immediately noticed a much more responsive rudder – now you’re talking! It was like driving with all the wheels done up tight. Lower heels gave a much better angle on the pedals and I noticed I was now operating the pedals with the outer edge of my feet, as I recall on the Incept. Line drag was minimal but now the wood laminate pedal board creaked and the zip tie hinges were a bit mushy too.
I’d already ordered another slab of LDPE chopping board to make a pedal board out of something more water-resistant than compressed dust, as well as the extravagance of proper marine-grade hinges (well, that’s what it said on eBay). I tried a quick bit of disc sailing too but it wasn’t really windy enough – more on that later.

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As I neared Badentarbet beach the g-friend happened to swing by and, showing her some moves, I  was amazed how sharply the boat could turn at low speed in the shallows, almost like a handbrake turn. Of course that’s not a particularly useful attribute in a kayak unless a WWII mine bobs up in front of you, but it’s good to know it worked. I also got a chance to test my newly bootied Kokotat dry pants – they worked like they should, too.

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Back at the house, I realised the pedal lines had been cut before considering the need to move the pedal board forward for tandem paddling. Luckily, more Dyneema turned up next day, so I re-used the former yellow cord for the rudder lifting lines and ditched the saggy red paracord. Much tauter action.

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The wheeled cord locks turned up too (right). I had a suspicion they wouldn’t work for adjusting rudder lines and I was right. They need tension from the same direction while snugged up against the edge of a stuff sack or something. I tried doubling the lines with two pulling the same way but the red Dyneema is too thin, hard-surfaced and slippery to work with these locks.

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I settled on a ‘truck tarp knot’ then got the idea that the locking guyline adjusters off my Vaude tent might do the job – and they glow in the dark too! My Odyssee has guylines to spare.

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Speaking of tension, nursing the loose prototype rudder over to Tanera wore me out much more than it should have – or maybe I just wasn’t paddle fit, having not been out since Mull. I set about making small improvements, including adding two holes in the boat’s back deck triangle (as Gumotex do) to make a cleaner run line for the pivot lines. It’s no great pleasure stabbing a red-hot poker into your favourite IK, but a side benefit is the rich aroma of burning Nitrilon rubber, not some cheap plastic. I’ll track down some nice eyelets later.

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Once I realised the rudder board had come undone because I’d mounted the nut plate wrong, it was clear the strap looped to the last deck line sleeves weren’t doing much. The main mount was through the drain hole, which relied on the large nut plate (left) below to stay in place, plus the saddle strap (left) limiting any yawing. The whole plate could be slimmed down to resemble Gumotex’s factory version.

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So I think I’m going to follow up on my own speculation and either form a triangular nut-plate below the deck to help keep the rudder plate in line with the boat or I may make a new long thin plate (yellow, left) that reaches back past the kayak’s portage strap. With a slot to get round the handle, I’ll poke another hole in the deck and this way the plate will have two mounting points plus the saddle strap and will not deflect.

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Rudder 1.1
While waiting for more chopping boards to turn up, I went out for another run with the Mk1.1 set-up. Much windier this time – 15 to 20mph from the SW. Normally I’d not go out in this, but the point of the rudder was to ease effort and improve control just before such conditions set in.

That was the theory – in practice I  struggled to get out of Old Dornie harbour against the wind and soon had to put in to readjust the pedal lines. What now, ffs? The luminescent Vaude clamps were effective but not a 4-second job like they should be. They can go back on the tent – better line locking mechanism needed.
If I’d looked back I’d have noticed the rudder plate had become dislodged yet again by the forces pushing the boat around. That explained why getting right out of the harbour was such a slog, let alone tackling the 15-knot headwind and lashing rain. Deceptively, there were few whitecaps out there, but a deep swell was rolling through, probably lifting the rudder out of the water. Who’d have thought it was midsummer’s day.

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Turning back, I hoped I might get a bit of a run on the wind, but control was even worse – shades of Ningaloo but without the mangos and barramundi. Back at the pier, it was a relief to see it was only the rudder plate at fault, although I’d not have been surprised if it was just too windy for any sort of IK-ing today. While waiting for what-do-you-think-I-am-a-bloody-taxi-service? to turn up, I strolled along the exposed shore on the off-chance of finding some LDPE jetsam, but all was glistening seaweed and frayed rope.

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Rudder 1.2
I’m running out of time with the luxury of having the sea at my doorstep. That evening it occurred to me the rudder plate was always deflecting clockwise because the lip of one glued-on reinforcement plate underneath stopped it turning the other way. I did what I’d considered initially and glued a thin strip of LDPE to act as an opposing locating edge so the plate sat more securely once saddle-strapped down to the boat’s triangular stern.

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This surely should be enough to keep the plate in place, but while I was fiddling I made a template for the triangular nut plate which might further help locate the rudder plate (right). When more LDPE turns up I’ll cut one out and melt another M6 nut into it. if this doesn’t work a longer plate with another through-the-deck fixture below the portage handle (as visualised above in yellow) ought to fix this once and for all.

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Other jobs:  trimming off the board’s unneeded flab to make the current haxagonal shape, filing down the edge of the rudder body where the lifting line rubbed (right), and one more tweaking of the rudder pedal lines.

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I headed to back to the harbour where it was still blowing about 15mph from the SW but within a minute suspected it was pivoting again, possibly from the pull when dropping the rudder. The added locating strip wasn’t enough. Who knows how Gumotex manage it but on this set-up the surefire solution is a second in-line fixing point (as above) and perhaps that triangular under-plate to stop the mount pivoting once and for all.

Partly, these issues are due to underestimating the forces that a combined 120kg of paddler in a 4.5m-long kayak moving at 4mph puts on a rudder and its mount. Add some wind, current and waves and how the small blade is fixed to a big boat becomes critical. Nearly there, brothers and one clear benefit: the ability to sit the kayak on the ground with no skeg stress. I can see me leaving the rudder on there full time and adding some sort of bombproof lock-out to make it the mythical articulated / lifting skeg.

Read about the MkII rudder.

2016 Seawave with rudder option

Seawave main page
My MYO rudder (MkII)

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The 2016 Gumotex Seawave has had the stern slightly adapted to take an optional rudder kit. They’ve also improved the velcro bands for the optional deck by using Nitrilon, but it’s the rudder that’s the interesting development.

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Coincidentally, I was  halfway through adapting a cheap SoT rudder for my Seawave (left) and the factory version (going for £200) gave me some good ideas. The Gumotex rudder kit could be easily fitted to first-model Seawaves, and possibly to other Gumboats with similar triangular stern decks.

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For the time it took to make mine I could have fitted a Gumotex kit ten times over but with only these pictures I was unsure exactly how it was secured. I suspect there’s an additional unseen plate underneath the stern decking to help jam the whole set up securely into the back triangle of the boat.

Otherwise the plate would be prone to distortion under rudder forces, giving a mushy response. I got that on my prototype version.

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The Gumo’s rudder’s retraction method seems to be pull-up-and-in, (left) whereas my SoT example above is a more conventional swing-up-and-over which puts the rudder right out of the way over the back of the boat. IMO this is better for negotiating tight turns in narrow sea chasms where an unexpected swell could crunch your protruding rudder blade.

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At the pointy end the pedal board looks reassuringly basic (and easy to copy) and the only obvious difference between an old Seawave are the two line guides on the stern deck (right) which I added to my boat to make a straighter, drag-free pull on the lines.

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