you are correct not ac reef they were prob fishing broken bottom and wrecks between the 2 reefs.
I have been fortunate enough to have some good #S passed on to me from older capts. Mostly loran but i then find them with loran and save into chart plotter.
But you can tell from the depth finder when over it
Some good books out there though, and some you will stumble along. sometimes it might only say rky on you chart plotter.
Lot of thoses pieces have been acting like artificial reef for hundres of years.
Check out divebooks books. Very accurate and detailed information.
The klondike and england banks are prime examples of natural bottom spread over a large area acting like reefs.
Small low lying pieces often produce the best fishing for most species.
Capts used to dump their own stuff over the side years ago before reefs. aka Dumps Hard to get any #s on them but still produce to this day.
you will like the divebooks