I also made a video of the hinge in action.  It can be seen in the below link.  

https://youtu.be/gusYdEuSSz8

David is pretty generous crediting me for the design as he provided most of the inspiration.  On a materials note, I think polyurethane is a nice material to make it out of because it is cast-able.  That way you only have to turn one hinge on the lathe and the rest can easily be made identical from a mould.  Polyurethane comes in all sorts of hardness and flexibility so you could pretty much tailor your hinge from slightly flexible (I can't really see a benefit to that) to very stiff with glass or other filaments to reinforce it.

I've uploaded a drawing of Darren's rolling hinge here , and there is a photo of it here.  A drawing of the simplest rocking hinge  is here.

The subject was gone into in some depth here:

 http://www.junkrigassociation.org/technical_forum/3302473.

Jim Creighton wrote:

I I agree, aluminum would probably be a better material. I was thinking plastic at the time because a friend who was dealing in high density plastic design offered to manufacture some test pieces for me. I never did go forward with that because of other priorities at the time. I think too that you had moved on to cambered sails as a better alternative.

The thing is, that you need a pairing of materials that don't fret and gall against each other, as aluminium to aluminium will. If you use aluminium tubes for battens, you need plastic conical hinges. I don't know of any breakages of plastic hinges - does anyone else?

Jim, I note that your design of hinge involves a lot of rubbing against the end of the tube, which therefore must be machined very smooth and true, and I wouldn't know how to achieve that without a large centre lathe. I prefer a rolling or rocking form of contact, with the least amount of rubbing, for less wear and tear. Darren has devised a design that has rolling contact in the horizontal plane of articulation, and the usual form of double cone with a cylindrical central flange has rocking contact against the ends of the tubes. Unless there is a major amount of compression in the batten, it doesn't matter too much that the axial contact area is small.

If I may coin a phrase: rock'n'roll for ever!

I I agree, aluminum would probably be a better material. I was thinking plastic at the time because a friend who was dealing in high density plastic design offered to manufacture some test pieces for me. I never did go forward with that because of other priorities at the time. I think too that you had moved on to cambered sails as a better alternative.

I recently found a file in my filing cabinet that might be of interest though now maybe just academic interest. See in my album, Miscellaneous Junk Photos.

Arne we may have had a discussion about this but it was a long time ago.

I designed a batten hinge using an insert to be made of a yet to be determined material. I wanted a low wear design so I made the centre node to be spherical so that the batten ends would always land on a maximum surface area to avoid hard spots and uneven wearing. Note the pipe ends a slightly chamfered to further spread the load. It could be even more chamfered perhaps.

Along with the drawing I found correspondence with a supplier of plastics. It read in part:...Needle Spar Ltd. have looked at the drawings and, according to Robin Bliain, were "impressed". They are going to try it out." I never heard anything about it again.

Cheers, Jim