I understand that the wrecks refresh periodically. How does that work?
Suppose my character "Z" comes upon a wreck.
1. Z shoots the wreck and there is loot, which A tractors in. I understand that Z can't loot that wreck again.
2. Z sees the wreck on his nav map but does not approach it. I assume that Z can loot that wreck later if it has been refreshed and someone else doesn't loot it first.
3. Z approaches the wreck, which shows that it has been looted. Z then leaves. I assume Z can come back later to loot that wreck after it has been refreshed, unless someone has been there first after the last refresh.
4. Z approaches a wreck which appears to be 100%-- fully refreshed, Z shoots, but there is no loot. It could be one of those wrecks that never has any loot, but suppose Z knows there is booty in that wreck because he has been there before with another character. What happens then? Can Z wait for a refresh and return to collect the loot? Or is that wreck forever closed to Z because he tried looting it and failed?
Wrecks reset upon server restart which I think is about 9am UK time.
Each ship can only claim a wreck once, meaning if you want to get the same wreck more than once you'll need to do it on new ships every time.
If you shoot a wreck that was already claimed nothing will come out of it but it will still register that your ship shot it and you will then need to make a new ship to try and claim the wreck the following day.
The first person to get to the wreck will receive the loot, and, over some amount of time, usually when no one is in range/in system with the wreck, its HP will regenerate to full. However this does not reset the wreck. That only happens after every server reset. (Which is 0600 UTC I believe? 4AM east coast america)
The wrecks only drop goods once per load. The server restarts every day at a specific time, which is when loot gets loaded back onto the wrecks to be looted again. However once it's been looted for the day, it can't be looted until the next restart. The healthbar is irrelevant really.
There was a trick of firing a missile/torpedo at wreck and relogging, but with 1min-rejoining-after-F1ing-prevention it is unlikely to work on Disco servers. The loot will disappear before you could return. Therefore you will need another ship, as others said, it can be a random /restart ship.
So if my character "Z" goes sells his ship and buys a new one, he can loot that wreck so long as it has been refreshed and no one else looted it first?
Suppose my character "Z" sells his Sunburst and buys a Stargazer, then sells the Stargazer and buys another Sunburst. Does that count as a new ship? Or does it have to be a new type of ship?
You'll have to make a new character entirely, as opposed to a new ship. You can salvage from a wreck one single time on a character, or at least to my knowledge. It could have changed in my time away.
So you'll need to transfer your loot off, delete the character, and recreate it.