An objection to treating these ships primarily as ASW frigates classifies them as light frigates because of their size and combined diesel and diesel (CODAD) propulsion. Gas turbines offer a more straightforward way to mount machinery on quieting rafts in a frigate hull, although that does not necessarily make the work easier. Acoustic quieting matters for ASW, but a frigate has other duties as well. Diesel efficiency gives the ships useful range for their size across the South China Sea and Pacific. The case for CODAD accepts an acoustic compromise in return for endurance suited to those operating distances.
Chapter · 1:12-2:37
Diesel propulsion, acoustic quieting and operating range
The propulsion argument weighs gas-turbine quieting against diesel efficiency and the distances Chinese frigates must cover in the South China Sea and Pacific.