Twenty five people responded to the online questionnaire on this website during this period. Three of the respondents were female and 22 were male. Ages ranged from 23 to 70 years (average age 47 years). Five classified themselves as beginners, 15 as intermediates, and 4 as expert sailors (1 unrecorded).

• Comments about existing rigs

"I am not a sailor anymore. I am an engineer who likes bright ideas"

"Pretty simple solution, but structurally efficient"

"The mast does not have any aerodynamic function, even though it is big"

"Well I'm not much of a sailor at the moment, but I am interested in using some sort of sail to drive a "grass" skate board thing. And maybe use the same sail to drive a wind-surfing board. Two boards, one sail!"

"I use a very trad sprit sail on a home built clinker dinghy. Performance not great, ease of use 10/10, appearance 8/10"

"Demanding to rig/trim. Expensive. Well advanced product with excellent performance"

"Classic sail outlines are pleasing to the eye. Performance seems ok, but hi performance traditional rigs seem overly complex"

"I use a 6m Aerotech sail mostly. It suits the local conditions and is quite responsive in medium conditions"

"Expensive, difficult to rig, very hard to tune for different conditions"

"I am a dedicated wind surfer. However, during the last couple of years I have become more and more interested in kite surfing. The reason for this is the small amount of space a kite surfer occupies"

"Today’s sails are really good, they are light-weight, can withstand rough conditions and they look fancy. Only drawback is the price. One brand-new sail often cost around $1,000 (in Denmark, Northern Europe)"

"I'm happy with them they work well. I'm looking for something a little more portable"

"Comparatively easy to use, moderately priced"

"I sail a small sloop rigged boat. Costs are very reasonable and the rig is easy to handle"

"Very good for the kind of sailing that I do. I use mostly a 7.5M sail with a 103L sailboard. The rig is mostly of carbon construction and monofilm for light weight"

"I use Neil Pryde rigs on my Mistral boards. They perform well but I need several complete rigs to handle changing conditions. The Pryde sails are over-priced in my opinion"

"Mature technology, works well"

"I sail a Mirror dinghy and would like to try your sail"

"Good. Have sailed everything from Optimist to 4 masted Barque. Currently sailing Rob Feleroys Nordj 2 sea kayak with 2 bendy aluminium masts and 2 basic triangular sails. It goes!"

"I agree with their limitations as described in the New Scientist article 28.7.01. I windsurf mainly on Canberra's Lake Burley Griffin where wind conditions are extremely variable thanks to the local geography. Hence need to change sails relatively frequently"

• Comments about the transition rig idea

"Interesting"

"Brilliant"

"Looks promising for use with sea canoe: ability to reduce sail area/stow in rising winds would be great"

"I love innovation! I think its great that you are doing something different, and in an environmental way. Wind is free! Getting the most out of the wind would be ideal, and if you can have one sail for all conditions then even better. Your transition rig may just be the rig to have!"

"Interesting, would love to try one out"

"I don’t race anymore, but still push my gear when I go playing. Your concept is great to look at, but will be too heavy, too fragile and simply function less efficiently compared to modern surfsails. I’m quite sure you will continue your quest despite the above. Good luck"

"Great idea, but I doubt it will work for high wind windsurfing. In fact I feel sure it will flop except for engineer freaks, who can’t really surf too well...(I’m an engineer myself - but sailed pretty well 10 years back when I was no. 7 in Europe. I worked extensively with my gear and among other things designed fins)"

"Very interesting"

"Very interesting. I like the idea of automatically adjusting to wind speed"

"I find it extremely appealing to have one rig that would fit all weather conditions. I need not use time to prepare several rigs before entering the waters"

"Ingenious! If it really does work, it would revolutionise wind surfing for beginners/intermediates who are not experts in rigging up (experts can prepare a rig in a couple of minutes, where as beginners often fight for a half an hour with mast/boom/sail to make things work"

"I would be very interested if it's portable and easy to set up"

"Excellent. Appears very versatile"

"Cool idea, ideal for sea kayaks I would think"

"I think is a good idea if the performance (lift, drag, stability, weight etc.) of such a sail is better than the current product"

"Sounds great" (x2)

"intriguing"

"As a mechanical engineer I am very intrigued. As a sea kayak sailor I am currently limited to reaching and running but if I had a couple of these and a decent leeboard then perhaps I could tack more efficiently"

I was intrigued by the problem of finding a suitably elastic sail material. My experience with elastic fabrics is rather limited, but I have found them inclined to stretch to a new elastic limit a la Hooke's Law. (I have the baggy track suit pants etc to prove it.) Have you thought of selecting a point along each batten and splitting it there into a Chinese fan? These fans provide the user with a variable area in contact with the air, while being at the same time made of semi-rigid material. It would seem to me that the original inspiration for the Chinese fan came from the wings of birds. Varying the area in contact with the wind is after all what you are about.

Bats never evolved 5 digits, each one ending in another set of 5 digits due I suspect to factors other than practicability. I suspect their genetic endowment was just not up to it. But I guess that the more branches there are in the tree making up the wing, the less the need for stretchy sail fabric.

With a conventional sail fabric (eg nylon) each segment of the new sail would behave like a parachute with one or more loose lines, ie with channels created via which air can escape. It seems to me that the task using conventional materials is to close the segments between the battens which make up the surface of the wing. Another way would be to have a line under constant tension running along the trailing edge of the wing, which would be a bit of a challenge"

The idea of using a Chinese fan approach is an interesting one. It would be a half-way house towards the method used by birds - overlapping flight feathers. The challenge would be to develop a reliable control system to ensure an aerodynamically effective surface that would work equally well on both tacks (ie: with the apparent wind coming from either side of the sail). My strategy so far has been to keep the rig as simple as possible while learning about its properties, and thus it helps to have the sail as a simple elastic membrane. But I shall certainly think about your interesting suggestion.

• Would you consider buying a transition rig?

"never"

"depends on price, weight and performance"

"depend price"

"Yes: for about £200 (canoe size)"

"Yes, if the price is right"

"Yes I would be tempted to buy one. If it does what you say it will if it is durable and the cost is reasonable. Good Luck!"

"possibly, if the price were sensible"

"Yes, if I’m proved wrong (but I’m not likely to be)"

"Depends on the cost and performance. Your new scientist article mentions your quest for better performance. Weight might also be an issue."

"yes - price dependant"

"It would have to be in my price range and cover several types of conditions"

"YES! If the price was maximum $2,000"

"Maybe, but I'd want to experience performance first hand. I'm not convinced it is a performance equivalent for the sloop rig on my boat, although I've always been interested in junk rigs (especially Jester), and that single sail idea seems to perform well"

"Not unless some scientific and on-water testings can show that it gives a better sailing experience"

"perhaps"

"Yes, if not too expensive"

"yes. I am moving to the Gold Coast of Queensland, Australia. There are many houses with water frontages, but the need to sail under bridges to get to open water limits the size of the sailing vessel one can bring to one's dock. A sail that can be 'destepped' at will is a very sensible idea here, on vessels from 16 to 30 feet long. Do you have an agent?"

"Yes, Although as a grippy canoeist previously living in Cornwall and now living in Scotland, I would want to see one to see if I could make it first"

"Definitely yes, but I would be even more tempted to wait and see, as with any new technology. Having said that, I think you have vertebrate evolution in your corner, which is worth something to say the least. I wish you every success with it"