I would have thought a towed array would have been the go with the OPV's as its a bit more flexible and easily deployed from them. Perhaps a hull mounted sonar could be scavenged off something that is being decommissioned. I don't see sea axe as a deal breaker.
Why does an OPV need to get involved in this at all? With the advent of UUVs quite capable of doing these things (like trailing an array), why have a noisy sound source like an OPV attached to it? Probably all an OPV needs is a short torpedo warning array, and that’s a pretty high-end scenario at play there. At best, an OPV might have a part in deploying these UUVs, but even then shore facilities and craft of opportunity are probably just as well placed to do so.
In advanced, high threat areas, it won’t be an OPV deploying UUVs – that’s the place of real warships capable of surviving the threats. OPVs should be back in home waters doing all the local security functions that will be in high demand in any security emergency. After all, the enemy are just as capable of deploying UUVs from their own craft of opportunity. Every dodgy fishing boat within range of our coastline will need inspecting. Perhaps even some of the larger commercial vessels on the usual transits to our ports. That’s the full-time job of an OPV in even the lowest threat level scenarios. There will be more work than they can handle, I expect. They can’t be off chasing every POSSUB a tail generates. They’d never get anything else done. If the ASW threat is that serious and widespread, the better response is serious and dedicated ASW search and prosecution assets (air, surface, sub, seabed sensors & UUVs). An OPV is a terrible compromise on those priorities and a distraction from its true purpose, IMHO.
BTW, I think the 80 m requirement comes out of limitations in berthing/manoeuvring in Cairns. Can’t remember where I read that, but that’s my understanding.
