twin groove furling foils
 

Flipping through a copy of the West Marine master Cataloge ('05), i noticed a bit in an "info box" citing one advantage of twin-grroove furling fouils being that you can use them to fly twin headsails (poled out wing-on-wing) for downwind work.
Years back, first encountering twin groooves, and not (then) being a racer savvy to their advantages changing sails, i had assumed that twin groooves existed for that sole purpose (flying twin headsails). Asking more experienced folks i knew, i was assured that doing so would be highly detrimental to the foil, the sail's luff tape, or both. While some racing foils (such as Harken's snap-on carbo-foil) are clearly not intended for this treatment, others (such as Profurl's burly round extrusions) seem shaped to accomodate it.
What's the real deal? May twin headsails be flown from a double-groove furling foil without damage or serious hassles? Note: i'm definately not questioning whether twin headsails should be actually rolled up together; that sounds like a definate recipe for damaging chafe.

I'll say that we have flown twin headsails from a furlex furler without problem,.
I can understand that the luff tape comming out of the extrusion at 90* angle to both sides could increase chafe and bending loads to the aluminum and in high winds could in theory cause trouble, we did not expirience any in moderate conditions.

It can be done, but...
 

Hello,
As Brian notes, it is possible to wing-and-wing stays'ls in twin-groove foils, but heavy use will harm the sail. And in any event there are better sail choices for running; drifters, assymetricals, that sort of thing are lighter, better-shaped, and easier to handle. And twin running sails are notorious for generating "death rolls". So I'd reserve the twin feature for what it's best at: quick sail changes.
Fair leads,
Brion Toss