On to actually pulling stuff out of the water. I'll try to keep
@ThirstyBarbarian 's TMI from distracting me.
There's more or less two things that you need to consider when choosing a salvage crane. #1 is capacity (how much can you lift and how far off the side of the vessel?). What you have on board to support divers is another aspect of capacity. #2 is when you can get there. That's divided into two parts, mobilization time (how soon can you leave port) and transit time (how long does it take to get from your homeport to the salvage site). I'm assuming for the mobilization time that the ships are in port, not doing something else, and not in a scheduled maintenance period.
Recall above that we're looking at lifting a ~80' x 50' x 1000 lb object and we would like to have significant diver support systems. You'll want a reasonably large deck to put stuff on, a 60'-100' crane (minimum) and some dive support systems. We'll be using the divers to hook big stuff to the salvage ship's crane and also to search for/pick up smaller stuff from the seafloor. While the depth itself (47') isn't that much of an issue, dwell time on the bottom might make a bigger difference, as would having a really good idea of where you are on the bottom. Of all of the requirements, the crane boom length and the dive systems are going to be the limiting factors.
So here are a few options:
US Navy assets:
I'm having a lot of trouble sorting out what salvage assets the Navy has on the East Coast. It doesn't help that they're in the middle of replacing their salvage ships, so the mix of ships available seems to be a hot mess of old ships like the
USNS Grasp and chartered ships like the
Kellie Chouest. The Grasp's lifting booms are probably a little shorter than you'd like, but it's set up as a salvage ship and has lots of other lifting tackle that could help manage the load as it come aboard. Both of those ships have plenty of dive support gear. Regardless of which one it is, the ship would likely be coming from Norfolk, VA or Mayport (Jacksonville, FL). Those are 350 and 250 NM away (respectively), and the ships in question travel at 10-13 knots, for a total travel time of 20-36 hours. Mobilization time on these ships would likely be a day or less; just enough to get some fuel and load up some groceries if you don't have them on board already. Mobilization plus travel time are in the 2-day range, which is what the President said we should expect. I would guess that this is what the Navy is doing, but here's a couple more off-the-wall suggestions:
It's possible that the Carter Hall is also the salvage ship. I don't know what dive support systems they have on board, though I would suspect that they're fairly limited. You could also see a bunch of outfits like the SEALs wanting to get in on the action. If the Carter Hall is the salvage ship and doesn't have its own dive support systems, that's probably the most likely scenario for dive support. The Carter Hall's top speed is over 20 knots, and it's homeported in Norfolk.
USCG Buoy Tenders:
The USCG has a bunch of buoy tenders whose only job is to take care of all of the aids to navigation that keep mariners off of the rocks. The
Juniper class and
Keeper class are good examples. They don't have the dive support facilities, though that could be supplied from other ships in a pinch. They also have nice large grapnels that you can drag the bottom to hook stuff without a diver. The downside is that you'll probably do some damage to whatever you were picking up. If time was of the absolute essence, you might use a buoy tender if it was close. They run at the same speed as the salvage ships above*, so unless they're in the immediate area it's going to take a day or so to get there. They're also either working or in maintenance nearly their entire lives. That's good because you don't have to worry about mobilization time, but bad because they might be working buoys 200 NM on the other side of their nominal home port.
Civilian Assets:
You have some potential classified information issues with civilians, but let's set those aside for now and just look at the boats. I can nearly guarantee you that there's a crane barge that can lift the payload sitting (or working) in the Port of Charleston. If there's not one there, there's a barge you can roll a tracked crane on to. They almost certainly have commercial divers in the same port, with a boat that they can work from or a trailer that they can roll on to the crane barge. Travel time is great because you're less than 100 miles away. Your tug could push you out there in half a day. The problem is mobilization time. It's not so much getting the barge ready to go, it's getting the contracting sorted out. If the company doesn't have a pre-existing contract with DOD, it will take at least a week to get contracting sorted far enough that you can go out and work. And that's on an emergency basis for a barge that already has the crane on board. If you're rolling one on, you need to do some engineering to make sure the deck can support it, and make sure the crane won't roll the barge over (or break the crane) when it moves the boom over the side of the barge. That's going to take a week*.
Everything would be easier if the companies involved already had contracts with DOD for marine services. That would cut the contracting time down dramatically. Unfortunately, those are going to be companies like Chouest and Hornbeck (located in Louisiana) or companies that serve the naval bases in Norfolk or Mayport. That doesn't save you transit time and the mobilization time is going to be the same.
The end result is that you're highly unlikely to see a faster response time than 2-3 days for a salvage ship, and anything else is likely to not have the tools that you need to get the job done. As noted upthread, would you rather use a Formula 1 racer or a tow truck to get a car out of the ditch? The F1 car can get there faster, but it doesn't mean it's the best tool for the job.
I've rambled enough now. Any questions?