BTW, a minor detail is that it was a grappling hook, not an anchor, but that is not a consequential difference.
Actually, I noticed that too... and it cleared up something for me... it's a good possibility that explains why the 3rd dive
had to be done.
Although I'm not as familiar with the keys specifically (Wookie?), the routine many Southeast Florida local area boats use (because of current) for wrecks is for the divemaster to "smart bomb" the wreck with a buoy, line and a chain. They chain in, return to the boat deck for a briefing on the conditions, the dives are performed, the divemaster returns to remove the chain.
On technical dives that's not always practical... the divemaster is often not qualified to be that deep, in that case the boat charter is just providing transportation and surface support. Several other strategies can used... a diver from the team is selected to "jump" the wreck, and once it's clear he has succeeded the rest of the team hurries down to meet him. The problem is he is piling on extra deco waiting for the rest of the team. Alternatively, the entire team smart bombs the wreck together, pulls the chain and leaves together drifting with the buoy/line on deco together (my personal favorite method.) If the team is skilled, this works extremely well even when one or two of the team are weak. The boat knows where everyone is on deco, nobody has tangled bag lines, you aren't flying like a flag on a pole in a hurricane.
If the viz is poor, team is too weak or too large to all jump together, nobody wants to (or is gassed for) the extra deco, no divemaster, etc... then a solution is to use a grapple made of iron rebar. Grapple the wreck without having to put anyone in the water. (Curious the word "grapple" instead of "anchor" is mentioned in the complaint, it leads me to believe it's a deliberately selected word.) Do the dives, then when everyone is back in the boat, pull up some line, tie it to a cleat, pull the grapple out using the boat; the soft rebar facilitates this by easily bending straight. The problem is sometimes you can't free the grapple from the surface... then an adhoc and nearly always subpar plan "B" has to be formulated, and a lot can go wrong.
I've been in this exact circumstance before, more than once. You are tired, and already fizzing, now you'd best haul ass down the line as absolutely fast as you can (for several reasons, time pressure being only one of them, crushing the bubbles fast another reason)... then you are confronted with a grapple which is by definition jammed in such that it is going to probably be some serious work to get freed, adding insult to injury you need to swim the grapple a ways off the wreck and drop it in the sand to be sure it doesn't foul again. On a rebreather after two dives, this is a reliable way to induce hypercapnia (hmmm, wonder how I know that?). So classic, I actually teach this scenario in my classes as an example of how to over breathe the scrubber as a result of excessive effort. My solution is to bailout to OC before freeing the grapple, then go back on the loop once the ascent is started. An alternative approach if no one is prepared to do another dive is to recover just the buoy (or leave it and hope for the best) and come back for the line and grapple another day.