The self-steering aspect of the twizzle rig was not an issue with us. To achieve the 'clew ahead of the tack' position with the jibs unfurled would require even longer poles.
When designing from scratch the governing factor of jib
area is the length of the pole you can stow on board. Our poles were stowed on deck
and so limited by the curve of the deck
. Longer poles could have been stowed up the lower shrouds. We didn't have that problem as we had a No.2 jib already and managed to find a second hand jib that pretty well matched it and then made the poles to suit the jibs.
We set the twizzle with the clews aft of the tacks which created a nice lift
to the bows as demonstrated by the dappling of the ocean by the downdraft from the jibs. Autohelm
7000 did the steering
very ably all the way with the exception of me having to replace the magnetic clutch
600 miles off Brazil
with my head
upside down in a cockpit
locker in 20 foot swells!
Where you will get the 'self-steering arrow flight' effect is when you are well reefed down. Then, as you let the poles forward and roll up the jibs (without easing the downhaul) the clews naturally go ahead of the tacks.
But now you are talking of serious wind
if you need to reef that much, say 45 knots+ and by then the short handed cruising man is thinking of lying ahull in your own slick (which works well, bye the bye)
Spinnakers are good fun and really pull her along but the thought of a husband and wife crew dropping a 3,000 sq.ft. bag when the wind pipes up on a prancing foredeck just doesn't bear thinking about IMHO.
Are we cruising or racing
here? Does another day or three at sea make a difference?