Re: Correct knot for the anchor line?
Opinions vary greatly on this as with most things. I recently read some testing that was an eye opener to me. I had always used the thimble splice until last year.
This testing/evaluation revealed that the thimble splice/shackle connection was the second most troublesome method, ranking right behind tying the rode directly to the chain or anchor. Part of the testing showed that thimbles (especially Galvanized) were subject to hidden corrosion (especially when used with a stainless chain, anchor or shackle). The corrosion was almost always under the rode where it couldn't be seen; subjecting the rode to failure by being cut, sliced or abraded when under tension. The other part of the problem was the shackle wearing thru or corroding the the relatively thin thimble thus again causing a wear/failure point. Another stated issue with thimble/shackle setup is that most people don't wire or ziptie the shackle pin to secure it, which again leads to potential failure. The last problem was that thimbles and shackles won't pass thru a windlass.
According to this testing, the chain splice was the most secure, chafe and trouble free connection. The reasoning was 1) the rode when spliced correctly to the chain (tightly) moves with the chain not back and forth on a hinge point at that connection 2) simplicity-1 connection eliminates all of the other components in the system that are subject to their own individual or collective issues. I'm looking for the article now so that I can post it for review. In the mean time here are two versions of the chain splice, the second allegedly being the most secure:
Chain Splice:
http://www.animatedknots.com/chainspliceboating/index.php?L%20<br/>w.animatedknots.com/chainspliceboating/index.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com
Warp Splice
http://www.bluemoment.com/warpchainsplice.html
I went with the first. I scuba dive on my rig and my anchor, chain, rode setup is considered life support equipment-not something to skimp on or do wrong. With that in mind I manually check the connection prior to every outing. If in question, I would resplice-but haven't had to yet.
It's counter intuitive to think that a shackle pin could work its way loose but I've seen them wrench tighted at the beginning of a dive and "finger loose" at the end. Bottom line no matter what connection you use, wire your shackle pin.