CAPTAS

[lastdingo]

So there were three CAPTAS (low frequency active/passive towed variable depth sonar, huge detection ranges and not countered well by anechoic tiles or the sub being silent):
CAPTAS-1 for corvettes (300+ t)
CAPTAS-2 for small/medium frigates (4,000+ t)
CAPTAS-4 for big frigates (6,000+ t) and bigger ships

Then came CAPTAS-4 Compact in 2016, claimed to combine CAPTAS-4's capabilities while being able to fit on the same platforms as CAPTAS-2 (confirmed by fitting into 4,500 ton FDI frigate).
This would mean CAPTAS-2 and CAPTAS-4 are obsolete now, all you need is CAPTAS-1 and CAPTAS-4 Compact.

So why the heck does Thales still advertise CAPTAS-2?

 

[H_K]

Captas 2’s footprint remains smaller than Captas 4 compact and can fit in smaller corvettes such as the ~2,600t Gowind 2500.

Comparing both independent tow versions:
Captas 2: 16m2, 16 tonnes
Captas 4: 45m2, 25 tonnes

Not to mention some navies may not need the full Captas 4 performance in shallow or littoral waters, or may not want to pay for the best solution.

 

[Titus K]

Here with the same Captas 4 original as a point of comparison
The Polish Navy chose Captas 2 on their AH140