The Twinning lines probably caused more problems on our
boat than any other system, largely because this was one area where we chose
not to copy proven Ovington practice.
Conventional fairleads were mounted by the chainplates but
then, wishing to keep the side decks clear of fittings, we chose instead to
lead the twinning lines through slots in the deck then, via a small turning
block, to cleats mounted under the decks beside the spinnaker sheet cleats.
Another advantage of this system was seen to be that,
because the twinner cleats were further back, the helm would be able to control
the twinners through the gybes whilst the crew was dealing with the pole,
therefore speeding the manoeuvre up. Unfortunately this did not work in
practice as the cleat was still in an awkward location, and to make matters
worse the continuous twinning line rope had a nasty habit of getting tangled up
with the spinnaker sheet next to it.
We quite quickly changed back to a conventional 'cleat on
the deck' system, with the line led across the boat in front of the mast, which
also kept the cockpit clearer.
No sooner than we had done that, we hit our next set of
problems - firstly we found that the lightweight 4mm line we were using for the
twinners stretched sufficiently in gusts for the spinnaker guy to rise a few
millimetres and pop out of the gunwhale cleat, with consequence loss of control
of the sail. This was cured by using 3mm purple Spectra instead.
The second problem was that the original fairleads mounted
by the chainplates were themselves too weak - on two or three occasions they
simply snapped under the pressure of the twinner line - usually in the middle
of a big race out at sea! Eventually the fairleads were replaced with a more
substantial version incorporating stainless steel ferrules.
The twinners themselves terminate in a small stainless
steel ring through which the spinnaker sheets pass. The sheets have
strategically placed knots in them, with free-running plastic bobbles (rope
stoppers) on the sheets, forward of the knots but aft of the stainless steel
ring. The knots can go through the aft turning blocks, but the bobble prevents
them going forward of the stainless steel ring.
The knots are located on the sheets so that, with the
twinner not-quite-fully-in (ie with the guy just above the gunwhale cleat), the
spinnaker pole is held just off the forestay. This means that the crew doesn't
have to spend time carefully adjusting the guy in the gunwhale cleat during
gybes or windy close reaches. All-in-all this is a very nice system, although
we did eventually use whipping twine on the sheets to catch the bobble, rather
than a knot - experience proved that whipping twine goes through the blocks
more easily, and that once used a few times the knots go so tight that they
cannot be undone again.