Only once have we had the spinnaker shackle catch on the rigging and release itself, but once is enough!!!
A little velcro strap that takes seconds to wrap around the shackle virtually eliminates this type of failure and is so easy to put in place.
Two pieces of velcro, hook and weave, stuck together and then a slot cut into one end to thread the halyard or shackle through and you have a solution for that very impactful sudden dropping of a large flying sail in the middle of the night.