I've had a couple of failures recently and am replacing old lines and changing some other hardware. I read the articles about tuning and recommended line sizes but when it comes time to buy cleats, block, and lines, I often don't know what to get. Is a breaking strength of 2000lbs enough for a spinnaker halyard? How much load should a mainsheet block or a boom vang block be able to handle? Any guidelines on how to estimate the various loads on the boat? Primarily the halyards, both the lines and the clutches or cleats that hold them, the vang block on the boom, the main sheet blocks, the backstay fittings, the forestay fittings.

Thanks