Bill S,
AIS also shows ECHO approaching with an ETA in the search area in about 15hrs
My guess is they will use HMS Echo to do a sonar map of the search area. Whilst HMAS Ocean Shield will prepare the Blue Fin 21. So maybe on the weekend will be the Blue Fins turn finally. Of course then it still takes a long time. They will search grid patterns and retrieve the Blue Fin 21 maybe every 12-20 hrs to download its sonar mapped data and exchange fresh batteries. There is a long road ahead. They may not positive ID the wreckage for another week or 2.