As far as I'm aware old shipwrecks are not modelled in the game. If there is a mod for this I'm sure someone here will point you to it. Having said that, you can collide with ships that you have torpedoed and are sinking or have sunk to the bottom in shallow water. I have had that happen to me once.
Nemo
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"I'm afraid there is no disguising the fact that King's obsession with the Pacific and the Battle of Washington cost us dear in the Battle of the Atlantic".
Sir John Slessor GCB, DSO, MC, DL
AOC-in-C Coastal Command RAF
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