The design of soft wing sails for cruising

Dear David,
Excellent forum, so full of useful information. I see you have built / sailed even more interesting sail types than I realised. Perhaps, in that mythical time, when you have nothing better to do, you could produce a book (e-book?), which I am sure many would enjoy.

I can see that for the ordinary folk (in my case, rather too much of an armchair sailor of late) testing our 'good' ideas by asking you first, is rather tempting, so trust that you will not mind a few simple questions.

A sail with a single sided 'flap' involves a lot of work with making a good connection to the wing section. Although a full double sided sail would involve more sail cloth, would it not be much easier to construct, and being simpler, perhaps no more expensive?

You mention that a hinged wing cannot point as high a double sided sail where the camber is locked in on each tack. For the most part this is of no significance, unless you are fortunate enough to sail a very slippery craft. Whilst I dream of building a very slippery proa, the reality may a fat cruising catamaran (Heavenly Twins giving so much for your ££s), the fat-cat may need the help of the engine to work to windward on occasion. In this case a sail that can motor-sail and point high will be of use. The thought is that a light line (ok lots - 2 per batten) could be used to lock in the camber. Would it work / be worth while?

Is your mizzen going to be a full soft wing?
Mark,
Short answer to all your questions: No.
No book; I'm too busy making things and sailing.
Single sided after part to the sail is easier to assemble.
Adjustable cambering lines don't work; they're too stretchy.
There isn't going to be a mizzen, just one larger single sail.

The construction of the carbon spars is nearing completion, and sailmaking will commence soon.
 
Hi David,
Still trying to decide if I'm going to take on such a project...
Question...
What is the reason to use the Mustang cloth or the other one?
Why not use sailcloth? Is it cost based? Of is there another reason?
 
Soft cruising Dacron sailcloth can be used. I used Richard Hayward's Sunwing http://www.heathcoat.co.uk/marine for my last wingsails. It's UV protected, and better value than others that are not so protected.

Mustang (also Odyssey III) is preferred for junk rig and derivatives because it is soft, and reefs and furls better than Dacron sailcloth; it is a cover material, and so needs no extra covering to protect it when not in use; and is usually less expensive than Dacron sailcloth.
 
Soft cruising Dacron sailcloth can be used. I used Richard Hayward's Sunwing http://www.heathcoat.co.uk/marine for my last wingsails. It's UV protected, and better value than others that are not so protected.

Mustang (also Odyssey III) is preferred for junk rig and derivatives because it is soft, and reefs and furls better than Dacron sailcloth; it is a cover material, and so needs no extra covering to protect it when not in use; and is usually less expensive than Dacron sailcloth.

Is it stretchy?
Why is it not typically seen used on Marconi style sails?
 
Is it stretchy?
Why is it not typically seen used on Marconi style sails?
It's stretchier on the bias, but reasonably stable along the threadline. Bermudan/Marconi sails need minimum stretch in all directions, so they need a tightly woven cloth with a resin filled weave. Junk sails and derivatives do not need this. The battens distribute the loads across the cloth, and the battens are sheeted to further distribute the loads. Junk sails have been made from Polytarp, Tyvek, nylon bag-making cloth etc, on a very minimal budget. Of course, some of those don't last long in UV exposure.
 
Just to show that I haven't been idle, here's a photo of the carbon fibre battens, hinges and noses, and a photo of the yard under construction.
 

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That's a nice job, David ! I'm sure this will be a good rig !
I hope to see the result on Tystie ... quickly... ;)
 
Dear David,
Thanks for your reply, as short as is deserved.
You can tell I am a coastal sailor (so far), and do not straight away test my thoughts against - 'what will happen when things go wrong, in a rising gale and lee-shore, at night'
Is your single wing-sail going to be going to be smaller than the previous junk sail? (which always looked twice the size I would like to handle)
When you have time, it would be interesting to know your techniques used in moulding the battens.
Look forward to seeing progress, the finished article, and of course hearing how she performs.
cheers Mark
 

That can't be possible in practice.

I assume you are running with an infinite aspect ratio.

Try an aspect ratio closer to what would be achievable on a sail and see what happens.
 
Some early photos:
 

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