Before hoisting the spinnaker I inspected this shackle and double checked that it was latched. I remember staring at it, thinking I would never trust my life to a quick release mechanism so easily released as this.
The spinnaker flew perfectly for hours, and then while putting it away I realized the shackle had blown apart, the result of being dragged over the lifeline. No excessive force, just the the weight of the sail and sheet as I pulled it on board. Somehow the circle pin came off, allowing the pin to shoot out the other side. This is a common failure mode, one I have experienced before. No excessive force, just the the weight of the sail and sheet as I pulled it on board.
Today's experience simply reinforced my tether decisions:
1. Harness carabiner should be locking but with simple release. I like the Kong Tango because it is large enough to clip railings and is easy to unclip even with wet, cold-numbed hands. I really like the feel in my hands. I also like that I can clip in with one hand, something I cannot do with a snap shackle.
2. Jackline carabiner's must be locking type. I like aluminum rockclimbing carabiner's", which seem to remain jamb free so long as I treat them with waterproof grease annually. I like simple climbing carabiners, since I generally leave the tether on the jackline and unclip at the harness end when entering or leaving the cockpit.
Kong Tango on the jackline end of the tether. They like a snap shackle for the harness end, I don't.
8 mm UIAA certified 1/2 or twin nylon climbing rope. It has the toughness and shock absorbing capacity to handle any conceivable fall or misstep without generating rib-breaking impact forces or overloading the jack lines or anchor points.
4. Custom tether lengths. I use two leg tethers. The short leg is 2 feet and the long leg is 8 feet. These lengths better suit my specific boat. The answer for yours could be different. However, I'm willing to bet that 3 feet is too long for the short leg on most boats.
Phase I: These were tied from 1-inch tubular nylon climbing webbing. I also inserted a Yates Screamer for testing, though it was later removed. These are the simplest to make and are quite safe, based on generations of rock climber experience.
Phase II: After many experiments, these are the tethers I use.
- 8mm climbing rope for shock absorption (easier on the ribs).
- Kong Tango at the harness end.
- Sewn ends (can be knotted--do not attempt sewing unless you have access to pull-testing equipment).
- 2'/8' lengths (fit my boat). The short leg just kept getting shorter.
- Small "parking clip" so that I do not have 2 biners clipped to my harness (inhibits unclipping in an emergency).
Note that in both cases the middle carabiner is cow hitched and can be moved. This is important to getting the best fit. The cow hitch is secured with a seizing to prevent sliding (hidden).