Wow Eric! Thanks for that answer. I really didn't expect you to fully explain it, as I had a feeling it would be a long explanation.
At any rate, I now understand the theory and it gives me something to think about.
Something to think about, indeed...
I'm sorry - tried to resist, but just had to come in here. Long live the lively anchor stousch.
I certainly would recommend re-thinking it - long and hard, and you as well my dear Eric, old friend, because I think your theory is just wrong.
With all due respect your analogy of pulling the rode taut between two vehicles is just not comparable. The protection the heavier chain rode gives is from the catenary, and the extra tension/load it takes to
lift it off the seabed, which if all chain is a lot - way more than a comparable length of synthetic rope rode. But this protection of the anchor from being subjected to a direct pull on the shank,
only lasts up to the moment it is finally pulled straight. When you reach that point, then whether the rode is nylon or chain, you just have the pull of the boat transmitted straight to the anchor, and the composition of the rode is almost irrelevant, as it is then just becomes
one very strong 'string' pulling on the anchor. It is then that the weight of the anchor, and how deeply it has bedded in becomes the critical factor, but not until that point, because until then it has really just been locating the end of the rode.
Sure up till then it has been resisting the weight of the rode, but until the rode is effectively lifted clear of the bottom, it really has not been feeling much of the actually pull of the boat, just the weight of the rode, and then
not so much until nearly all is lifted because of the friction between that still on the bottom and the mud etc still gripping that chain. And, don't forget, the pull is never constant, and the second there is any let-up, the weight of the rode pulls large lengths of it back to the bottom. So it stands to reason, the more weight in the rode, within reason, the longer it will be and the larger the force must be before the anchor is subjected to the full load of boat
which includes the force needed to lift the rode, surely. The lighter the rode, the earlier it will be pulled effectively straight and the full pull of the boat go on the anchor.
To take the comparison one step further, the ultimate full force the combined elements are capable of transmitting to the anchor, once the rode is straight, by definition must include the effort/tension required to lift the rode off the seabed, so one can subtract that from the ultimate force of the pull, meaning the net force the boat can exert is the total force minus the force to straighten the rode...which relates directly to its weight...you do the math, as you US guys say...
My case rests....