Wouter,

There's no real strong argument either way - I guess it's just personal preference. I prefer to use two shackles as it means that maintenance is a little bit easier and wires are less likely to get damaged.

This weekend we had a trap wire go at the handle, once we were ashore it was just two minutes to lay the boat over still fully rigged, undo the upper shackle and replace the damaged wire - back up and on the water again in under 10 minutes. Had the same thing happen a couple of times on my old Tornado (over 8 years).

I did try a single shackle approach on one of my Condors but we broke the trapeze several times at the top end and couldn't figure out why as we had it rigged the same way on a previous Condor with no problems at all. On closer inspection we realised that once the rig came under sailing load (the mast bend trapped the shackle tight to the mast)the trap wire stopped articulating on the shackle so that we were actually 'working' the wire just below the talurit and metal fatigue was the result. Since then I've had a preference for two shackles.

A lot will depend on the arrangement of your hounds fitting and the space available to you.