I like a Harken cleat, mounted to the Ronstan swivel. The Harken swivel will bend allowing the jaws of the cleat to open up and allows the halyard to slip or release. The Ronstan cleat is garbage, there's no metal wear strip to keep the halyard from digging into the cleat at the bottom of the jaws. The mix and match of parts has been working very reliably for me on the last four Vipers I've had.


(edit)- I use a Spinlock on the tack line. They have an excessive failure rate, and I usually keep a spare or two on hand. Some last longer than others. Just for the way my tack line is setup, its the best solution. I'm not sure I'd want one on the halyard. Seems to me they would be too easily released if it were exposed.