Left Lay, Right Lay?
 

I have a roller furling 200% light wind drifter attached forward of the roller furling genoa. It uses a light furling gear and is designed to roll in so that the clew is on starboard side (furler rolls in counter clockwise). My theory: Since all twisting forces on the luff wire is clockwise (looking down from the top of the mast) I would think the luff wire should have a right lay. The sailmaker installed a left lay luff wire, which, after only 9 mo., has failed, clearly from an unwind and bind. Please help me with any insight. Thanks!!!!

Mike

Details, please
 

Is the drifter on a traditional furler with a foil over a wire, etc -- or is it a free flying furler with no standing wire? I am assuming free flying.

How did the wire fail? I am assuming a birdcage and fail from your description.

Couldn't the system jam just as easily on the way in as on the way out -- making the lay of the wire moot.

Do you what jammed to cause the wire problem?

Bob

re: left lay, right lay?
 

I apologize for my lack of knowledge on terms, but I'll give this a try: From the top, a halyard has a free spinning "bullet" to which the swage eye of the luff line attaches, and the luff line is sewn into the luff of the sail, and is seized at each end into a triangle attached to the swage. The bottom swage is attached to the light roller furler, with one furling line to furl (sheet is pulled with furling line uncleated and freed to unfurl the sail). I burst of wind apparently was the source of the failure, either by whipping the furled sail until the wire failed, or perhaps unravelling the sail a few feet and then twisting the wire to breaking point.

I've had a time getting my mind around this, so I built a little model to find that all the forces would have "tightened" the lay in my configuration (left lay).

I've got maybe a better question: what does a failed luff wire look like when it's "birdcage" failed compared to "overtightened" failure?

re: left lay, right lay?
 

Oh, and as for the lay being moot, I think a jam on the way in or the way out would be a twisting force in the same direction either way.

Birdcage, etc
 

A birdcage occurs when a wire is unlayed -- the outside strands will open and expand outward. The wire looses a lot of strength, the outside strands do not take the load, and everything is transferred to the heart.

I have never seen a wire fail due to the lay being tightened enough to break strands, but it could happen.

Most wire in furlers is damaged from the jamming the furler (usually with halyard wrap). It can happen on the way in - winching the furling line, or on the way out -- winching the sheets.

If things are jammed the lay will tighten in one direction, and unlay in the other -- in and out with the sail, depending on the wrap direction.

I have seen a torsion rope used in the luff of free flying sails -- I think Yale makes it. It would take the question of lay out of the equation.

Bob