​Cool thread.  Thanks.

Ozone has 2 x 2.5:1 chord:thickness mast​s of modified Clarke Y section, 17m high.  The original rig had the same sail area as the stayed rig.  It was too powerful so the owner chopped 4m off each one.  The dragging of the mooring down wind is hard to attribute to the wing masts as they would have reduced the windage vs the stayed rig.  If the boat had been sailing back and forth it is more likely that any dragging of the mooring would have been upwind, not down.  regard;ess, the owner sailed it from Melbourne to the Gold Coast (thousand miles or so?) without problems.  he then had to sell the boat due to family health problems.  I looked it over for a prospective buyer and it was in good nick.  Unfortunately, we did not get to go for a sail as someone else bought it.  I have heard nothing since it was sold.  The bearings were expensive machined stainless and Acetal spherical roller bearings.  I doubt they would have been a problem.  No idea where the centre of mass of the mast is, suspect it is just aft of the max thickness (~33% of the chord) which is where the sheer web runs and is also the axis of rotation.

Wing masts are scary for cruisers.  I had one on Elementarry during a cyclone (50 knots) and in the turbulent wind in the canal, it was rocking like a mad thing, probably would have capsized if it wasn't tied down.  The wind at the top of the 7m mast was totally different from the bottom.  No way could it weathercock.  At sea in a gale, you could probably reverse the masts and run downwind with a drogue or sea anchor.  In a marina or close to a weather shore in a big breeze, I doubt it would be much fun.  

Modern sails and wing masts are efficient.  They are also expensive, short lived, require a lot of expensive hardware and a fair bit of skill.  My aim is to build a wing rig which:

Is big enough for light air without extras

Is easily reefed or removed if required

Has twist control from zero to lots, to remove the need to reef in a lot of situations

Has no sail track or slides and does not need mast bearings.

Adopts it's aerofoil shape automatically

Has a high aspect ratio

Has no external frames, battens, etc

Has no internal strings, pulleys, frames or joints.

No vertical loads on the sail part so it can be built of cheap material

Solid leading edge

Is light and cheap

Thanks to you guys and the JRA for the motivation and ideas on how to do this.  

State of play:

The mast (3 x 3m pieces joined), weighs about 16 kgs as i miscalculated the number of tows required for the first section.  Should have been ~12 kgs all up.  Not a big deal for the test bed.    The first piece of wing was built from a flat panel with different weights of glass and foam locations so it would bend into the correct curve.  It was close, but no cigar due to the difficulty of a smooth  leading edge transition to the skins.  The next one is being done on a masonite half mould using standard grade polystyrene with carbon stringers and egg crate (areas with the skins joined together to remove the core shear from the core)  sections.   First half panel (2.5m x 0.5m) weighs just under 1 kg.