I was not looking to install one, just get a feel for the setpoint. A minimum setpoint of -200 mbar gauge (80 inches of water) tells me what I need to know. That's a significantly higher vacuum setpoint than I expected. I would have thought something like 20 instead of 200.
For our raw water system, (which is a lot simpler than a later model SM) the AC units quickly shut down on high pressure if there is insufficient water, the genset quickly shuts down on high exhaust temperature if it lacks water. Adding a high wet exhaust temperature alarm to the main drive engine will cover pretty much all the cases.
Fort Lauderdale, FL, USA