What changed in ship designs in the 600's that made it so that ramming other ships was not as valuable of a tactic? Wasnt Greek fire rather rare in usage? Were ships to big and not fast enough to be used a rammers anymore? Or was it just a lost tactic?
There is a Naval Historian on this sub who will probably give you a longer answer, but I can tell you that reading about the history of the Italian Maritime Republics, it's pretty clear that ramming continued to be the primary tactic in Mediterranean naval warfare up to the introduction cannon-armed galleys in the early 16th century.