Sometimes these situations deliver knowledge far beyond their price
67Therapy: it seems to me you've learned about a contingency which could have had really serious consequences, if it had happened under other circumstances - say a bearing cage disintegrated offshore
, jamming the rotation of the foil or the swivel, and you had to drop the sail, rather than roll it. It doesn't bear thinking about....
And it sounds as though fate has added enough memorably inconvenient twists to the tale that it makes a great story, permanently etching itself not just on your memory, but on the memories of us fellow-travellers on the internet
(thanks!). Without leaving scars (at least, not for us !)...
I'd call that a win-win-win!
And msponer's further horror story (and this would be a REAL horror if it happened offshore
at the onset of bad weather
- thanks very much!) just adds further value to this thread.
As far as his question about the foils being pulled apart:
<<I'm not sure if this is endemic to profurl (which it was for me), or all brands of furlers. >>
I'm not sure to what extent, but I think this is a possibility with many designs, and it's one crucial reason I have just taken delivery
of a set of Alado headfoil sections (I'm planning to make my own end fittings and rotational mechanism).
With the unusual Alado approach, there are three things preventing this failure mode:
1) The foil is in two halves, port and starboard, interlocking by jigsaw tongue and groove (the section is the same for each half, flipped about an athwarthships axis)
2) Each half is staggered, so that a joint between two port foil sections comes halfway between a joint between two starboard foil sections. The sections are 1.5m (actually 5') long, so the minimum the stack would have to extend to allow free rotation of the tack end vs the clew end would be 0.75m. That's physically impossible without lengthening the forestay.
3) The halyard
does not run back down the mast
: it runs back down the foil. Hence there is no external force which could pull the stack apart, in fact halyard tension forces the stack together. Their system does not rely on fasteners or adhesive
to prevent the foil sections pulling apart, and does not need to.
There are aspects of the way it's implemented which I would personally have preferred to be different:
I purchased a section bigger than a foretriangle my size would normally require, partly for ruggedness, and partly because the sectional drawings on the Alado website for this (the biggest section available) showed a luff groove big enough to accomodate an endless halyard, which had attractions for me. (including providing an integral head downhaul)
It turns out that the groove was only a little over half the size indicated by scaling from the drawing, large enough only for a 6mm boltrope. (I'm planning to use slugs)
Furthermore I'm a bit disappointed with the finish of the ends of the foil sections, but it's a purely aesthetic point, and the ends are not visible installed
More puzzlingly: there is a radial cross-hole near one end of each foil, to accept a moulded stub protruding from the plastic bearings which centralise the foil over the headstay.
These bearings are split, and plug
together when assembled over the standing headstay, another cunning and user-friendly feature, making installation
In my case, at least, these holes are not circular, but lobed - the way holes in sheetmetal often are when drilled with a standard twist drill - and will have to be reamed to persuade the bushes to fit.
This was something I was not happy about, as that would remove the anodising. It turns out that, at least in my case, the cross holes were drilled after anodising, so at least I won't be making anything worse... The sections were at least cut to length and fettled (somewhat amateurishly, IMO) prior to anodising.
But those reservations aside (and frankly most people would barely share any of these, let alone all) it's a very well thought out system, and the extrusions appear to be of good quality.
Alado would have you believe that the minimum increment of foil length permitted by their system, without cutting any extrusion, is 5'.
I attach a sketch I did to persuade myself that, given that Alado sell half as well as full lengths, the true increment is 2.5'.
Alado give the impression that only the right hand configuration is valid, and that to get the situation on the left, you would have to order the right hand stack, discard the bottom starboard (half length) extrusion, and cut the bottom port extrusion in half. Which is silly - but without working out issues of 'handedness' to do with where the holes end up (which I checked per my diagram), it's not patently
(This is implicit, rather than explicit, in the way they quantise the available foil lengths)
I'm recounting this here, not to attack Alado, but to assist those thinking of ordering from them.