Tag Archives: Inflatable kayak sail

More kayak disc sailing

The IK & packraft sail Index Page

Windbag update 2016: the 3mm-thick 305cm-long glass fibre rod snapped. Not surprising with the bending it gets to fold down, but I doubt it’s worth repairing. I bought another length via ebay for a tenner. I went for a 3m section which is 5cm short (next length being 5m) but the sail can accommodate dektentthe slack. It felt more flexible but within a couple of days that broke in two places too. If I run 3mm rod doubled up I presume the bending forces will be the same, but if I run thicker rod I presume it won’t fold down three times to the compact 30cm diametre disc.
windppLooking again at the original Windpaddle, it does seem much of the cost is explained by the ‘proprietary’ composite rod they use, and there seem few easily found online reports of breakages. Prices seem to have dropped quite a lot too (as they have for the ebay knock offs by 50%). Could it be you get what you pay for after all?


sai01The other evening I hooked my old home-made disc sail onto the Grabner’s bow (left and below) and took it out on a loch to remind myself that it wasn’t really that good. As before, I found it difficult to get a good run before it flapped out or otherwise lost its drive.
sai-discMy Pacific Action V-sail will work better, but fitting that to the Amigo may require more D-ringing. I like the compactness and simplicity of a disc sail, but it was suggested that dishing like a bowl was the key to holding the wind and maintaining steady progress, even if it may be less effective tacking across the wind.
ParachutaiSounds plausible and WindPaddles are clearly made like that for a reason. Since then it occurred to me that’s why classic ‘descending’ parachutes (‘reverse’ sails) are bowls and not flatter discs which would shoot across the sky. Before I set about recutting my disc into a bowl shape I checked WP prices on ebay and spotted what looked like a knock-off: ‘Canoe sail kayak sail wind sail‘, now just £17 delivered. Cheaper than sewing and at 115cm deployed, it was midway in size between WP’s Adventure which at the time was selling for no less than £155 in the UK (now £110 with smaller Scout for £90). Someone assure me that a WindPaddle costs even a fiver to make in China, but see top of the page.
sai10sai-attachAnd better still, the no-name windbag folds down into three hoops of just over a foot in diameter (right – smaller than my red disc sail). Plus there’s an elastic hoop to keep it like that and a carry bag for the long walk back to the van. Out of that bag, the only changes I made were to replace the too-short control strings with my tape off the red sail which I find easier to handle. I reassigned a sling to hook the sail’s base to a floor D-ring back from the bow (above left). That was already fitted and was the only adaption I needed to mount the sail to the Grabner.
sai03The day before, with the visiting Nimbus family we’d paddled round the Ristol isles. Over lunch on Ristol beach I took my new sail for a burn up. First time out, not bad at all. I got a steady run and up to 3.9 mph on a breeze of no more than 15 mph and with very little faffing. The prospects were good. More wind was needed.
Incidentally, on the beach I noticed how very, very much unlike a sea kayak the Amigo really is. Alongside my old Incept, let alone the lethal Scorchio HV (right), the red boat looked sai12like one of those horrible inflatable kayaks you read about, except it happened to be clad in bomb-proof hypalon and pumped up like a basketball. And by the way, I finally fixed the seat in the Grabner with a rather obvious solution. Details on the Mods page if you’re interested.

sai-mullaEarlier on, coming round the southwest corner of Eilean Mullagrach, (right), the swell bouncing off the cliffs and crashing over outer reefs looked intimidating. Though we all managed fine, it was everyone for themselves. With heads bent to the task, the comparative speeds of our four boats was clear to see. Way out ahead and longer than your average four-door car: the cheddar-coloured P&H cheese cutter. No far behind, 12-year-old Boy Nimbus darted along in his 12-foot Carolina (later I GPS’d him at 6mph, same as the HV). sai-2botsFurther back Mama Nimbus and little sister Nima in the K40, all hands on deck. And out back Grabner’s hypalon clog – splish-splosh, splish-splosh Slap. Checking the GPS data (above left), the speeds weren’t so bad, it’s just that in the rough the hardshells cut through some 30% quicker.
A few days later the Solar was stacked on the Amigo (right) and I realised it was only a foot or so longer than the Gumotex. In that case the Grabner does pretty well for a 12-foot four-, 31-inch kayak that hauls two paddlers.
sai-windsBack to the sailing. Next day winds were forecast at over 25 mph (right) but as it was warm and only a 5-minute drive to a Loch Vatachan round the back, it was worth a crack.
sai-splasherA short pre-paddle suggested my cheapo windsail would probably get ripped off and blown to Lochinver, or else see me roll off the back of the kayak as it shot away from under me liked a snatched tablecloth. Upwind I couldn’t exceed 2 mph (left), but skimmed downwind at up to 5.5 mph providing I kept the stern right on the wind. And while I was out here, side-on to the one-foot fetch the Amigo felt secure, so not a completely wasted outing. I’d never set out to paddle in such conditions normally (actually I did once), let alone try sailing (actually I had once) so I called it off. Later, Ardmair weather station confirmed the wind had been howling at a steady 35 and gusting to nearly 50 mph.
sai-boatsWith the Nimbii, we ‘yaked over to Tanera Mor one afternoon; three IKs and two SinKs (left). I can see it from the window now, but realised I’d never actually walked up to the 124-m (400-foot) summit of Tanera Mor for a look around.
sai-tansouthUp on top a string of islets lead to the twin humps of Priest Island, 4.5 miles in a straight line (right). It was a ten-mile round trip I’ve mentioned earlier but may be beyond reach this time round.
Paddling back from the island, Mama Nim found my old Incept had picked up another pin-prick hole in the side. Wtf is happening to the K40? It’s a lot better than the armchair -wide Sevy they were borrowing before, but three holes in four outings? And it gets worse. On leaving the island the wind dropped to nothing so sailing was off. Instead, we were plagued by sea midges which rise from their lairs as soon as the wind turns its back.
Another day and a healthy northerly forecast at 10mph on the BBC which might mean 15 in real terms. I set off with Nimbus in his Scorpio ‘PK’ (plastic coffin) for a look at Tanera Beg’s arch he’d missed on previous visits. It’s a nice arch; we passed it a couple of weeks back, two-up in the Amigo.
sai-keensOnce clear of Old Dornie I threw the sail out and trotted along at 3.5 mph which won’t be giving me any nosebleeds but I suppose must be classified as progress. At least I found a good way of stashing the sail. Seeing as it’s right out on the bow, refolding it down to three hoops isn’t practical on the water without help or taking risks. But I could just pull it back and tuck the squidged sail under my feet and between my legs (left). Down here there’s little risk of it self-deploying and jumping overboard to become a most unwelcome sea anchor, but it can be thrown up in a jiffy to catch a breeze, just as with the PA.
sai-paddOnce we got to the two Taneras’ In-Between islands the wind remained but the waves were blocked so I threw out the air bag and trickled along again at about 3.5mph again. Then it occurred to me I could hold the sail leash in my teeth and paddle. I swear, Da Vinci must have felt like this on his good days. That worked well too: getting on for 5 mph but without the paddling effort to make that speed unaided. Plus it felt better than having the sail hooked to my pfd and stopped me talking unnecessarily.
sai-archersOnce past the In Betweens we crossed over to the arch (left), but found we were a metre short of water. Still, high or low water it’s a great mini-destination some three miles out of Old Dornie (see maps below).
sai-calmacerNow the easy ride was over; it was going to be a solid old hack back into the wind for Old Dornie. As we turned we were a little perturbed by what looked like the  Stornoway ferry heading right at us. I’m sure it never came this far north, was the captain asleep at the wheel or taking a deeper channel on the spring tide?
sai-breakerferryAt the last minute the CalMac turned away and a calamity was averted. A few minutes later its wake rolled in, breaking a couple of feet high just as we  passed a reef. It looked like a good picture so I sent Nimbus back for a shot (left) but by then the best of the surf had passed. If that was the swell kicked up by the ferry from a mile away and before it hit full speed in the Minch then I’m glad we keep our distance.
ferryspdTime to put the camera away and knuckle down for an hour’s bow slapping to Old Dornie. As I’ve observed before in such conditions, Nimbus in his blofieSinK paddled like he was stroking a cat, gliding through the waves in a seemingly relaxed procession. Me? I was loading 16 tons and what did I get? Slipping back further and deeper in bilge. Still, not alone for a change was less unnerving and I quite like a good work out on familiar terrain. You dial in the effort you know you can sustain for the duration and progress at whatever speed that delivers. From the graph above that added up to about 2.5 with occasional surges to 3 mph when my technique briefly hit BCU targets. The P&H PK seemed to hold a steady 3mph without trying.
sai-splarshThe wind had failed to live up to the forecast promise of dropping around 6pm and out in the mid-channel a few white tops developed; for me in the IK usually a warning sign it’s approaching the limits. I will speculate that I shipped less water than I would have in the Sunny which is a similar type of IK. Partly because of the upswept Amigo’s bow that front or rear doesn’t seem to be as much of a wind catcher as it looks. And perhaps too because the boat doesn’t bend with the swell.
In fact it was fun slapping the fat bow against the oncoming waves as I slowly hauled my way closer to Dornie. Old Man Nimbus can read wind speeds like a Tubu hunter reads the sands. He estimated it was blowing at 8m/sec which in English translates to 20mph. I’d angleferryhave guessed a bit less, as with the spring tide at full flow against it, it didn’t seem too much in an IK (as long as land appeared close by). As we neared the harbour a couple of other SinKs slinked by, tucked right under the shore, out of the wind. Get out here you cowards!

No Name wind sail
So – my conclusion of the no-name wind sail? Well, it’s a WindPaddle at the right price. Easy to fit to my boat and doubtless many others, easy to temporarily stash on the move and probably easy to repair. And easy to steer too; pull left to go left, usually. With the window pane it’s much better than my home-made flat disc of course, plus it’s less bulky and complex than a V-sail, even if a V will give you nearly 90° reach either side of the wind.
Surprisingly I haven’t found the lack of a rudder an impediment with the Grabner. Though there’s a bit less directional control, at the typical sub-4 mph speeds you can drag a hand or a paddle blade to bring the nose around. And interestingly, providing you’re close to the wind and holding a steady course, the sail worked pretty well when paddling with the leash in my teeth like the 3.30 line up at Cheltenham. I can’t say I ever managed paddling with the Pacific Action on the Incept for long before it flapped out. Plus there’s plenty of scope for hooking up some self-jamming cleats (left – more here) like I ran on the Incept.
Above all, the no-name air scoop is great value for money for the performance it delivers. For thirty quid it wouldn’t be worth making your own. Next job – see how the little Alpacka handles when yanked along by the wind sail.

Sailing slowly

For sailing the Incept less slowly, see this video set in northwest Australia a few months later. Full story here.

Not much wind today, but with a few refinements to try out it was worth taking the Pacific Action sail out on a regular ride over to the island.
I chose my big-faced Corry paddle and it has to be said it’s quite a strain (the opposite of a Greenland paddle) when you’re a bit out of condition. But then I bought it primarily for the packraft. What felt like a worthwhile breeze heading out to the island was probably more than doubled by the 4mph I was chucking out. Knowing I could afford to be, I was pretty tired once I reached Tanera Mor’s rocky shore. The state of the tide? who knows – coming in I think so it was with the wind, but I really think it makes little difference round here most days.
As the graph left and the video below both show, I had a bit of trouble getting it up and never got close paddling speeds while sailing back. But once I did get on the wind, it was a bit of a revelation to find I could pin the sail at a certain stance and, providing the rudder was on the case to, just sit back and enjoy the slow ride. It may have taken me longer to get back, but I could have easily read the Sunday papers, checked my email or just looked around and enjoyed the scenery, had most of it not been suffocated by the clouds of an imminent downpour.
It was also a surprise to learn I was not the prisoner of a given wind angle, but could modify it by up to 180° or maybe even more. At one point back near the beach, from the lapping of the passing waves across my beam it looked like I was paddling a few degrees upwind. Conditions were exceedingly tame but the cord-lock things worked pretty well and their position alongside the cockpit was just fine to slide them up and down.
At one point I tried paddling with the sail which I’d assumed would be rather tricky. Sure, the control cords got in the way a bit, touching my hands as I paddled, but it was possible to paddle lightly and so – as the graph shows – raise the speed with little effort to 4mph. Had I tried paddling harder I think I’d have outrun the sail, but it proves a good point: it need not be either paddle hard into the wind or sit back and sail; you can sail and paddle too if conditions allow- or enable it, gaining a bit more speed and exercise. I may try fixing the shock cord a little further forward to the nose which may help keep the sail up at marginal (low) angles or low wind speeds. I also need to tighten the webbing a little more, so the mast feet touch directly toe-to-toe so that, at the angle they’ve been locked against the masts, they’ll splay the sail out more readily.
The Google Earth screenshot of the GPS track on the right features the long-sought OS layer – useful as GE’s close-up resolution hereabouts is terrible. With it you can depict all the accuracy of a true GPS track over a detailed OS map. It’s a simple kml file found here. Download and open with GE and it’s there to click in the sidebar on the left when/if you choose to view OS mappery in GE. Thanks to Gael A. for sending the link.
As things stand today I’m pleased I bought the PA sail; primarily for its simplicity of installation, deployment and possible repairs, its ease of use in the hands of a sailing beginner like me, the compactness when furled, as well as its ability to pulled down fast and attached/removed from the Incept in a minute or two. All that remains to be assessed is the kayak’s stability in rougher and windier conditions. The forecast shows a bit more wind on Tuesday so hopefully there might be some surf-slicing sail action to grab then.
Below is a borderline dreary video shot at speeds not exceeding 3.6mph. I’ve had a lot of trouble with the buttons on my Go Pro camera (I’m not the only one) to the point where I was going to return it for replacement and sell it. But the place that sold it recommended a system update off the GP website, and what I assumed was a mechanical problem seems to have been fixed. Even then, as you can see below, at the bottom SD 720 res, the Hero struggles in the low light of some incipient Scottish dreich. When the sun’s out it’s much better; auto exposure may be better in the card-eating higher res HD modes too. I don’t use them.

Fitting a Pacific Action sail on Incept K40

See also this post as well as this post about using the PA in strong winds in Western Australia. There’s a video there too.

I’m pretty sure my 0.78m2 home-made disc sail is too small to push the 4-metre Incept along until wind conditions get beyond the pale. Recognising that, I tracked down a 1.5m Pacific Action for £175 instead of the usual £250 which is a bit much. As I mention here, you can easily make a V-sail yourself from bits of plastic piping and old trousers, but life is short and as I’ve experienced a PA in action in Shark Bay, I’ve treated myself. The nearest B&Q hardware store is half a day away.
They call it a ‘1.5m’ sail, but unless I am very much mistaken it’s more like 1.15m2 if you calculate the area of the Isosceles as 146cm across the top and 174 up the sides (graphic on right; or base x height of about 170 divided by 2). PA round those dimesnions up on their website to 150cm and 180cm,  but that still doesn’t add up to 1.5m2 or 16 square feet. Maybe I should chill out a bit; a Ducati 900SS is actually 864cc and so on. As you can see left, it’s about twice as big as my 0.78m2 disc sail and it certainly looks like a metre-and-a-half square, so perhaps my sums are wrong. And it’s bigger in the right area too: up high where it counts. Plus you can see where you’re going – always handy in busy traffic lanes.
The sail comes in a compact bag of less than a metre. Can’t weigh things here but they claim 1.9kg; could even be less. Inside you get the two, 3-part masts made of thick glass fibre, the sail, fittings and rigging or lines, plus adequate instructions* for what turns out to be a fairly straightforward task. These instructions and fittings are obviously aimed at hardshells, be they SinKs or SoTs. With an IK you have to improvise a little. It helped knowing that there’s a picture of a PA sail on the Incept website (right), as well as this Kiwi guy’s video (bottom of page). The supplied cleats (sliding cord locks) are tiny and I recall Jeff replacing them on his Perception tandem for Shark Bay, but see below. Because of the confusing instructions combined with my congenital density, I misunderstood their simply application. On my first go at sailing the PA I was holding and maneuvering the control string by hand, as I did with the disc sail.
sai-clipUp front the snaplinks (right) I’ve used to mount the disc sail also happen to be ideal positions for the PA’s webbing loop. And the bow handle ring toggle is the just about the minimum 12 inches ahead of the mast feet to take the shock cord clip (left) with which the sail springs forward when you release it. If that’s not quite enough far forward (as I think may be the case), I can stick a D-ring patch a few inches further forward right on the nose of the boat (as left). This position/angle may be more important than just getting a good spring forward, but also affect the sail support. We’ll see.
In Australia a few months later we did see. Further forward was indeed better (as right), but I suspect still not optimal. When you think about it, the front attachment for the elastic would be better if it was set higher that the level of the mast feet. That’s because when you’re reaching across the wind with the downwind mast almost horizontal with the hull (as pictured left), the angle of leverage to keep the upper mast up gets very low; at 5-10° the tensioned elastic is almost at the same angle and so the sail collapses as shown in this video at 1.16. This happened to me all the time in Australia as the sail was pulled low to cope with the strong sidewinds. If I go ahead with my nasal bowsprit idea as mentioned here, I’m now thinking it might also be an idea to raise it a bit; have an upcurved bowsprit so the sail is more readily held up when reaching (near-horizontal).
While in Australia I also pushed the snaplinks to mount the sail straps directly through the black lugs and not around them as pictured right. This was because the strong wind was pushing the sail mount (a plastic plate) forward, making it go slack, reducing the elastic tension and causing more problems with handling. But by the time I made all these adaptions we were locked into two days of headwinds so I never really had a chance to see if it made any great difference.
Back to the original mounting story set in Scotland in summer 2011. It all went together easily enough, until it became clear some fittings were missing from the pack which for some reason looked like it had done the rounds with a few previous customers. Most fittings were not needed for my IK, except the four ¾-inch self tappers with which you permanently fix the mast feet position in relation to your kayak’s deck angle and with the sail splayed. According to the instructions* and this picture I found on the web this is an ‘8g ¾-inch’ screw, but that seems way too long to have two from opposing sides – one alone would act more as a bolt than a self-tapper getting a bite, but that is what they recommend; the subtext is these screws are important to make a solid fixture. What’s not made clear (or is perhaps obvious) is that you ought to pre-drill guide holes deep into the plastic mast feet lugs for the screw can get right in there. Some hardshells will have a bevelled or convex foredeck which is why you must set the mast foot angle (MFA) specific to your boat for optimum operation. On my set up, the MFA is horizontal (flat) as I’m using a plastic chopping board idea as PA suggest to give the feet the all-important support and avoid wear on the PVC deck. The feet move around quite a lot under tension as you pull the sail this way and that but, as I found first time out, the angle of those feet against the mast (as well as the webbing tension) must be solid if the sail is to spring up and open or splay out.
The sail rolls down out of the way and doesn’t interfere with paddling, though it does mean yet more cordage hanging around; you could get in a right old muddle if you don’t keep on top of it. PA do advise paddling with a knife or a less pointy rope cutter. I have a quick-grab Benchmark one (left) attached to my PA.
It was gusting up to 40mph before the local weather station packed up, and at times the sea was covered in foam streaks and swell, so I went to a back loch for a spin. Typically by the time I’d crawled into a dry suit in case I fell out and got dragged along by the sail, the wind had just about died, but it gave me a chance to test it out in tame conditions. That evening my paddling speeds back into the wind were greater than anything I managed under sail, but I was getting the hang of it and even got the knack of running almost across the wind. The vid from that session isn’t worth uploading unless you’re having trouble sleeping; I hope to have another session when the wind returns and on a loch that’s longer to the wind.
Lessons learned: need those self tappers to lock the feet, luckily the local store had some that may do the job. And I’ve since located that chopping board a bit better to the boat with some slots and zip ties until a better solution is required. 

Rigging the sail-adjusting cleat
Working out how to rig the control cord to alter the sail angle was actually rather simple once I put my mind to it. As mentioned, you get some small plastic cleats in the pack whose use is unclear. But digging around online for an alternative cleat (as other PA users tend to fit), I discovered what the PA comes with are very much like, if not exactly Clamcleat Line-Loks. Now I know what they are, their fitting and application is more clear. It’s not illustrated or explained in the PA instruction leaflet* I received; in fact I’d go as far as to say that the tiny yellow picture of the rigged Line-Lok in the PA leaflet is the wrong way round compared to what’s illustrated in the Clamcleat gif on the left. But even though (as I found) it does work crudely when rigged the wrong way round, I think I finally get it now. A Line-Lok a nifty solution to tensioning a tent guy in the Arctic as the link shows, but as Clamcleat’s gif on the above right also illustrates, you need two hands to release it – not something that may be easily available in rough conditions while trying to grab your paddle and not spill your tea. But so far I’ve found in the light conditions I’ve been out in, one handed works fine and if it’s a real panic you just pull the sail down in a jiffy.
In fact, testing the correctly rigged locking cleat off a chair leg, it’s possible to achieve the release movement by spreading your fingers as long as it’s not too tightly jammed in the cleats, while adding tension (pulling the sail back/down) is certainly easy.
Having worked out how to string them up, the next question is where to attach them to the boat. By trial and error I found that cutting the supplied 4-5m line in half, rigging as above and then clipping the stainless steel clip to the K40 at the plastic lugs just behind the seat seems just right (left; it shares the left side lug with the rudder lifting line). Even though the Incept image with the red boat above seems to use the more forward points, fixed like this it puts the full sliding range of the locking cleat within arm’s reach while sat in the cockpit; or at least that’s how it looks on the lawn. I used the spring clips supplied to fix the control cord to the mast shackles, but at one point while sailing one unhooked itself from the shackle, so better to knot the cords securely to the shackle as PA recommend. To see how it sailed first time out, see this.

NB: A more recent set of fitting instructions were sent to me as a pdf from Pacific Action and are much clearer.
As far as I could see it wasn’t to be found on their website.

Homemade packraft or kayak sail

For my original post on the idea of IK sailing, with various videos, click this
For my first go packrafting with the sail, click this, and in a kayak, see this
A cheap ‘Windpaddle’ sail

A few years ago I got a batch of discounted Decathon Quechua ‘2 seconds 1’ pop-up tents (right; £20) for a desert tour I was running, and have a couple left over. Now everyone’s offering cheap pop-ups. People love the idea and though I don’t suppose this is a tent you’d want on the north face of Annapurna in a gale, when you arrive at a camp tired after a day of desert biking, you just want to click your fingers and, Abracadabra, you have a cosy shelter to call your own.
Whoever came up with the idea of flexible hoops sewn into a 3-D form to spring apart and make a tent or shelter was ingenious. I still marvel at it today. It seems a photographer John Ritson got to idea of adding fabric to a flat loop in 1985 and invented the collapsible Lastolite light reflector (right) after he saw a carpenter fold the blade of a bandsaw (See the bottom of this page). I imagine a Lastolite (a 38-incher costs £50) was the motivation behind the WindPaddle idea, but from a plain disc to a tent is quite a leap.
So I took a knife to one of my used Quechua tents.  Bad though it felt shredding a perfectly functional shelter, in the spirit of the Inca shaman, it will be reincarnated as a sail – or more ill-conceived clutter to shove under the bed.
Dismembering the Quechua gives two giant hoops of 4mm nylon-coated alloy and another of 6mm. Having been told that WindPaddles can deform easily under strong winds, I chose the thicker wire to use for the hoop (Gallery pic 2, below) in the hope of reducing this possibility. (Warning: when opened up these springy wires can fly about all over the place).

Cutting the thick loop in half and rejoining it with the metal collar/tube (don’t lose this bit) gives a hoop of around 40 inches or 1 metre diametre making a sail area of 0.785 m2 (8.45 ft2) – similar to a WindPaddle, but with negligible dishing. I built up the sawn-off end with some cloth tape to stuff into the collar-tube, and then taped it all up (so it’s easily undoable).
There’s enough fabric in the main body of the tent’s fly sheet (Gallery pic 1) to make two 40″ disc sails if you cut from the middle, so 1 tent fly = 2 sails. I only worked this out after I cut. You want to use each curved end of the flysheet with as much orange hem-sleeve as possible (Gallery pic 4) – it saves on sewing later. You don’t want, as I thought,  the flat middle section which of course won’t become a smooth disc once formed into a loop with the wire. Gallery pics 5 to 9 show how to gather up the slack, trim it, tack it down and get the Mrs to sew it up as if she hasn’t got enough work to be getting on with at this time of year.
Gallery picture 10 is the sewn-up sail with a handy gap at the bottom for I don’t know what and which also happens to coincide with the position of two little hooped tabs at 5- and 7 o’clock which you can use mount it to an Alpacka’s rearmost bow loops using mini snaplinks (Gallery picture 11). By chance there are 2 more sewn-on plastic rings at 10- and 2 o’clock to mount a control string. The length of string I used happened to be just right to wrap around the folded over tent, though it’s all under tension and pretty unstable; you might want something like a bulldog clip to stop the sail deploying unexpectedly. I also think my control string may be on the short side, but it’s what was lying around.
My disc tent doesn’t have anywhere near the dishing (depth) of a WindPaddle or an umbrella – like a spinaker sail I am told. I still havn’t worked out if this is significant (it is). One would imagine a deeper WP-like sail – a ‘bowl’ rather than a ‘saucer’ – would be more stable downwind but less good at tacking across it (probably correct) but what do I know? Last time I sailed a boat was over 35 years ago.
I suspect a flip-out disc sail like this is probably a compromise when it comes to sailing effectively, but then so are pack boats. If round sails were such a good idea the Vikings would have them. It may even prove to be not fully useful and so just more junk to carry about which is why, after trying the umbrella, I chose to make one for next to nothing rather than spend £140 ($215) on a WindPaddle in the UK. It was easy to make, is light (250g or 9oz), and it can swapped between my Alpacka packraft and Sunny IK in the time it takes to unclip 2 snaplinks and attach them elsewhere.
Other uses include something to sit on, a doormat for the tent, a wind break, sun shade or umbrella. There is a slight problem: you can’t see where you’re going, especially on the shorter packrsaft with a metre-wide sail a metre on front of you, but on most water that ought not matter too much and if it does, I can cut in a window (like a WindPaddle) if that is the sail’s only flaw.
As to how it sails, Monday after Christmas had a good southerly wind and the warmest day for weeks (ie: above freezing), but the reservoir I chose was a rink and looks like it’ll be that way for a while. It’s been the coldest December in the UK since records began so a test run make take a few weeks to complete. To see how it sailed first time out, click this.