I’m in an adjacent industry, with less risk of death or commercial loss, and the compressor backups only output to SCADA. The pressure regulation is all relay based and the on switch is a manual secondary contactor.
Also another problem I noticed is the engines are often on the ships controls (network maybe?) As the manufacturer name. Something like MANN1 and MANN2 or MITSU1 is a dead giveaway: thats propulsion.
I suspect that at least some ships/designs are done right ‘right’.
(1) the engine controllers are internal safety limits and have very controlled input ranges. Cummins engines as an example.
(2) the network has a ‘Battlestar’ mode where you can just cut the wire. People would still need to connect laptops or jumpers locally to control devices in anything beyond a ‘max’ vs ‘idle’ vs ‘off’ mode… but 100%, ready, and off should be enough in an emergency.