I’ve attached a couple of photos of my rig which was devised by wiser heads than my own and which I daren’t touch!: the first shows the uphaul (lime) attached to the downhaul (blue), the second shows the overall size of the loop in the downhaul. The boat came with a standard spinny pole and ramp system.
why don’t it slide down?
‘tiz a wonder and a marvel, and as a newbie I had to give some thought to understanding the spinny rig I inherited:
so here’s my punt at an answer:
the key is that the up and downhaul are under continuous tension (allowed for – or even generated by – the elasticated element in the downhaul rigging): in otherwords they are pulling up/down against each other and the pole is caught (by the ramp) in a loop where they join. because the loop is under up/down tension, when the ramp is horozontal it catches the loop, when its vertical it slides through. Also once caught by the ramp the pole is joined to the boat in three places: at one end it is clipped to the mast D ring, and at the ramp to a) the foredeck, by the downhaul, and b) to the mast again by the uphaul at the uphaul sheave. This rigging resists upward movement, and stops downward movement beyond a fixed point, and keeps the pole always under some tension to come back to the midline of the boat also.
The guy then effectively pulls the pole sideways to adjust the pole angle in the horozonal plane and the sheet keeps the other side of the sail under tension so the luff catches the wind correctly.
The upshot of all this is that the pole can’t slide down the sheet, even though it is simply clipped over the sheet, it is kept pulled up against the clew of the spinny by all these other splendid heathrobinsonesque forces.
also (or just putting this another way, the sheet and the foot of the sail form an angle at the clew of the sail and so the pole is effectively caught in the angle.
happy to be shot down on any or all emements of the above explanation …
all best wishes
Boris W6330 Delphy