Graham Cox wrote: Thanks Arne, I am slowly building up a database of information .  My somewhat limited

Stavanger, Saturday at 08:28 UTC

Graham

If you already have a rig with a good flat sail, then it may make sense to add hinges to get camber. That was what I did to my first flat sail in 1991.

However, I f you are to start from scratch, I recommend you go for straight battens and cambered panels in between. You will be surprised how docile the cambered sail is despite all that extra cloth. The HM sail profile is a good basis for making a cambered panel sail as several panels will be identical. You don’t need more fancy sail cloth for the cambered panel sail than for the flat one, but you will need some more of it of course.

Arne

Graham Cox wrote:Thanks...I remember an early PBO (2000) where you talked about 6% camber being indicated in wind tunnel tests as most effective.  Is that what you'd call moderate?  I have read Arne's articles and looked at the photos of his sail with a camber of 10%, if my memory serves me correctly.  I'll talk to my friend who is going to make the sail for me about putting some camber in.  He is a professional sailmaker who has made some interesating sails for proas etc and repaired numerous flat junk sails.  He has offered to build my sail as a gift but was thinking of a flat sail I think, being something he could throw together quickly.  I was reaching across the Whitsunday Passage yesterday, lying on the deck and looking up at my curvaceous sails which were pulling like a train and thinking about how effective (and beautiful) they were.  I feel less enamoured with my bermudian sloop rig though when a squall hits or I am running downwind with the jib poled out and the wind shifts, obliging me to gybe the whole contraption over, even less so when I have to gybe it back later.  This is less of a problem offshore but a self-tending rig really comes into its own when weaving downwind through an archipelago like the Great Barrrier Reef. Thanks for the feedback, it feels weird - and exciting - to have such a steep learning curve again after 40 years of cruising offshore! 

Stavanger 20101019 at 13:36 local time

Graham,

All the junks in Stavanger have 8% camber except the foresail of the schooner, Samson. That sail has 10% camber.

Arne

Graham Cox wrote:

David Tyler wrote:

Graham Cox wrote:I I am converting my bermudian sloop to junk sloop in 2011 and am thinking about flat sails versus cambered etc.  Nobody seems to be talking about hinged battens though, can anybody tell me what the state of play is regarding hinges?  By the way, I have a homemade Hasler type self-steering gear, with a trim tab on the trailing edge of my outboard rudder (long keel) with an offset vertical windvane and it works very well.  I often link my tillerpilot into the trim tab when winds are light and fluky or I am am motorsailing, with excellent results.  I'll post photos later when I am more organised.  Cheers, Graham

There are still a lot of people sailing around with hinged battens, made in the days when they were in vogue.
The drawbacks seem to be:
1. A perceived loss of integrity, when you cut your one-piece batten and put in a hinge. It is perfectly possible to make a soundly engineered hinge, and it is also perfectly possible to make a hinge that pops apart under load, or fatigues itself or the batten. Good design is necessary.
2. It's hard to get enough change of angle in a hinge, so as to get the amount of camber that is now being built into cambered panel sails. Two hinges can be used, but the forward hinge must be sufficiently far aft of the mast that it doesn't hinge the wrong way, and this makes it hard to get a camber shape.
3.In terms of aerodynamic theory and appearance, the sharp change of direction is not as desirable as the smooth curve that can be obtained with a cambered panel.

My wingsails have hinged battens, of course, and Pete Hill put hinged battens onto China Moon and sailed her from Brazil to Tasmania. There are two boats with a lot of ocean miles under the keel.
But all in all, starting from what we know today, cambered panels with rigid battens are the way to go,unless you are good at mechanical design.

Thanks...a friend told me the other day that he thought he saw Tystie sailing up Pittwater again, having seen you there last summer behind Scotland Island.  If you make it to North Queenland I'd be interested to look at your wing sails.  As for me I am trying to to do a cheap. simple, basic rig and may end up just going for a flat sail as I tend to reach and run most of the time, north with the trades in winter and south with the sometimes elusive northerlies in early summer.  If I do go offshore I just crack the boat off until she begins to move.  My Tom Thumb 24 is a five ton 24 foot steel sloop and it doesn't like being jammed up against the wind anyway.  On the coast, if I have to go to windward, I tend to motorsail, so the flat junk rig may be quite ok for me.  I have sailed on and alongside a sistership with a flat junk sail.  In light windward work in smooth seas, Arion. with her bermudian sloop rig, walked away from the junk, but as the wind and swell picked up the margins shrank.  Reaching and running we were evenly matched, though i had to work a lot harder.  Once we started gybing and reefing it was his turn to walk away from me.   I have been reluctant to consider the cambered sail because of a perception (no direct experience) that it may be subject to more chafe than usual. What is your opinion on the chafe issue?  I am most interested in easy running without foredeck work poling out headsails etc, and in the easy reefing qualities of the rig.  I don't really care how fast I am going.  I will nonetheless be interested in finding out more about the design specifications for hinges that do work provided they are not too heavy or expensive to produce.

Graham Cox wrote:I I am converting my bermudian sloop to junk sloop in 2011 and am thinking about flat sails versus cambered etc.  Nobody seems to be talking about hinged battens though, can anybody tell me what the state of play is regarding hinges?  By the way, I have a homemade Hasler type self-steering gear, with a trim tab on the trailing edge of my outboard rudder (long keel) with an offset vertical windvane and it works very well.  I often link my tillerpilot into the trim tab when winds are light and fluky or I am am motorsailing, with excellent results.  I'll post photos later when I am more organised.  Cheers, Graham

Gavin Dalglish wrote:

Rene & Lesley Verbrugge wrote:

Hi Gavin,

I made a start on re-typing the fact sheets (last year actually!) - in Word and .pdf format if they'd be any use? Who should i send them to?

How's Bretagne these days?  We left France in January and are now based in  Hong Kong having bought Crib last December. working hard to get her ready for cruising and hoping to leave next spring if all goes to plan!

Kind regards

Lesley and Rene

Hi both

Glad to hear of your progress, and of the work you have done on the Fact Sheets. I'm not actually sure of the best person to send them to - David, could you advise?

Best wishes

Gavin

Yes, send them to me, please.