I've been looking into anchors for the past week so... I'm an expert!!! Ha! One fairly long and egaging rticle went on about anchor size, large boat, small boat, stuff like that. I'll see if I can dig it out and link it. Among other things, it went thru the physics of anchoring, calculating catenary arc, force on the anchor, rodes bar tight. What it comes down to is chain is required the first (place favorite length here) feet. This protects the rope rode from wear on the bottom. Beyond that there is no calculatable benefit, other than not dancing so much at anchor. By the numbers, an all chain rode has more perceived benefit that actual benefit. This guy also said that choosing a smaller, stronger chain than BBB shows great benefits. Again, I'll see if I can dig it out.
I really do not pay any attention at all to "theoretical" anchoring information. I've been anchoring vessels of all sorts since the early 60's, both with all chain and some with chain/rope. I never anchor under "controlled conditions". We've somewhere around 1400 straight nights at anchor in various places around the WI, excepting a 5 day haulout a few months back. Nothing "theoretical" about it. There is absolutely
NOTHING perceived in an all chain rode with a snub line. There is absolutely no possibility that something underwater will chafe through all chain (see pic; this "something underwater" was tangled
in the middle of the anchor chain) or the chain to line splice will wear through. We don't anchor for the best conditions we expect, but the worst.
With a chain/line rode, anchoring in the SoPac and Oz, I carried a goodly number of fishing floats to "float" the line from the chain to the boat so it wouldn't wrap on coral heads or get cut on rocks. That takes about a hour to set up and half that to undo each time I anchored. Without the buoys, I couldn't sleep very well.
As for anchors, after over 50 years as a professional mariner, I completely blew off the idea of "next gen" anchors. My genuine CQR was just fine as were genuine Danforths (in their place), but there were places like the chutes in Admiralty Bay where it wasn't. Occasionally I'd see a boat stick in these chutes and other hard to hold areas. I'd go over and ask what anchor they were using. Rocna was the reply, each and every time. Not long after this, good fortune smiled on us as we were able to pick up an 88#er for a quarter of it's retail price. Hey, a cheap experiment even if it didn't work, right?
Well, for the next year we dove on that anchor almost every time we anchored and found the it rarely took more than it's own length to set! And I
NEVER back down to set my anchor (unless Med mooring). In several decent (60+kn) middle of the night blows it held perfectly. Same with tidal situations; reset in it's own length.
So, the old salt had to admit that there was something to the "new gen" anchor hype, at least for my purposes down here. In another area, such as the Canadian Maritimes, where I'm guessing the anchoring is mostly on rocky bottoms, I'd go with another anchor I'm sure.
I don't mean to sound "preachy", only to pass on real world experience to balance the "theoretical" anchoring information available to you on the web. In the end, all chain is basically no safer than chain/line if you don't have a proper snub line system. None of us can carry chain strong enough that if the chain is straight from the anchor to the boat and the seas are up. In effect your chain/line system is a chain/snub system, only the bit of the snub in the water is rather perishable.