I'm currently listening to Roger Crowley's City of Fortune via Audible. He mentions that during the Third Venetian-Genoese War, a Venetian admiral pulls into a harbor in the Aegean Sea, scuttles his ships, waits for the Genoese to slink off, and then salvages the ships and sails away. How did sailors do this back then? Would they have had confidence that they could definitely rescue the ships and wouldn't be stranded?
There are a couple of answers in this thread about salvage -- in the case of the Venetians, they were probably scuttling galleys, which are light ships anyhow. One way to get them back up without modern gear would be to partially sink two other ships (or pontoons--something of that nature), one on either side of the ship; attach lines to the sunken ship, and pump water out of the two pontoons until the sunken ship rises enough you can start dewatering it.