the twin poles

The length of each pole should be 80% (as on Alma) to 100% of the length of the mitre of each jib. Being too long is better than being too short but stowage is often a limiting factor. Stow on side decks or up shrouds.
The diameter of the end tubes were selected to fit the Harken pole end fittings. The middle section of the pole was a snug fit over the outer pole sections and pop riveted together. The poles were not anodised or painted and still fine 4 years later. The green insulating tape was to cover the pop rivets and stop snagging. The thickness of the tubes is quite heavy, about 3mm, like ally scaffolding.
The inboard ends of the poles were leathered to prevent chafe.

A nylon cleat is fitted near the inboard end to make off the clew outhaul. Not very heavy loads on the poles.

the best universal joint (version 2.0)

Made from 12mm Marlowbraid (polyester braid on braid). Not huge loads involved but essential that the pole ends can flex angularly and axially.
A simple knotting of clove and half hitches. The soft eyes sewn up then finished with a plain seizing.
The rope is blackened where it rubbed on the uncoated ally poles and oiled leather for 24 days.
The green insulating tape was added from new, in case there was chafe from the pole end fittings, but in the event it was not needed. Good for many more ocean crossings. Easy to stow and replace.

The shackle attaches the up-haul while the down-haul is bent on with a bowline.

running rigging (on 40' ketch)

uphaul - 12mm diameter. Used the existing spinnaker pole uphaul shackled to the top eye of the universal joint. Long enough for the universal joint to lay on the deck.

downhaul - 14mm dia.(ex. sheet used but could be approx 12mm dia.) From the bottom eye of the universal joint, forward to a block on a strop near the bows, then back to a cleat on the mast. Strop allows the fall to lead aft clear above the anchor winch, fore hatch and other deck gear.

outhauls - 10mm dia. From the jib clew cringle, through the pole end fitting, and along the pole to a cleat fastened to the inboard end of the pole. Not big loads.

sheets - 16mm dia. From the jib clew cringle, aft to the jib sheet car, to the sheet winch. Big loads here - the biggest size that the sheet block/self tailer will take.

preventer - spare 10+mm dia. Hung loose from the universal joint to the base of the mast. Prevents the universal from popping forward with the poles veed aft instead of forward. Leave plenty of slack for the universal to swing port and starboard in normal operation. We also used a very long tail from the bowline of the downhaul as a preventer. Not big forces involved.

More ...

A description of the setup, setting and striking...
The equipment used for the twizzle rig...
Video clips and picture gallery...
More development information and experience...