I am no fan of in-boom furling. For many years we have sailed a Catalac fitted with this system and it has been a "pain". Furling is achieved by pulling in a continuous halyard which runs over a pulley which rotates the central spindle around which the sail coils...well at least  that is the theory. In practice the halyard is likely to jam or the ratchet system that serves to lock the sail up or down freezes. We have been obliged to drop the mainsail onto the boom to get it out ofthe way on a number of occasions.

We have also experienced complete failure - the central spindle around which the sail is supposed to wind is, in fact a small diameter rod which sheared at one end rendering the whole system useless. Not something that you want to experiece when you want to get the sail down in a hurry.

The only merit of the system must be that it is less vulnerable that in mast furling - the length of the central spindle and therefore the strain that it experiences in smaller - I would not have in mast furling for love or money....

I take your point Tony-but your issue is surely with rubbish engineering  rather than the principle? I recall sailing close hauled off Cap de la Hague with a main rolled with a through the mast system-with a dramatic "sproing" the handle snapped in half and described a parabola into the sea 30yds away.

Subsequent examination showed a sharp edged machined fork in a pathetic casting held on with the kind of roll pin you might use to secure a car's window winder....

My problem with all the "easy" reefing systems is that they compromise the shape of the sail you can use, and therefore the boat's sailing performance. This is particularly true of in mast furling (although I think the sails are now better than the board flat, battenless "roller blinds" of the earliest examples.)

I accept that on larger boats it can be very helpful to have such systems, as hoiisting a big sail can be difficult for a small crew. But I think it is a pity that so many people have followed the trend and put such systems on small boats, where the loss of performance is proportiontely all the greater.

Is it because in-mast furling sails don't set nicely and drive the boat to windward properly that you see more and more boats motoring to windward?

The original article mentioned a fabric strip and groove up the mast. This system was tried many years ago by another manufacturer and the wretched thing flogged about when on the mooring and kept all the neighbours awake!

Modern stackpac and lazy jack systems, together with single line reefing work so well that unless you own a massive yacht the extra expense and complication of an in boom system seems to be just adding something else to go wrong. The fixed rigid kicker, as well as being very difficult to get 'just right' also detracts from the efficient shape of the sail. K.I.S. Keep It Simple!