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 leftover. 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 cozy 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 flysheet (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 spinnaker sail I am told. I still haven’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 windbreak, sunshade or umbrella. There is a slight problem: you can’t see where you’re going, especially on the shorter packraft 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.