I put a variety of colored lights above various
instruments in my
cockpit panel, each above a specific instrument. If a plastic bag or piece of kelp blocks my seawater intake, or if the
water hose breaks, or if a vane breaks off my seawater impeller
pump, a light goes on over the engine temperature gauge, because that is going to rise in a couple minutes. Of course an overheated engine idiot light, also sighted over the temp gauge, tells me when it has already happened. The same for the other
instruments:
oil pressure, voltmeter, and two lights over the
fuel vacuum gauge, a red one for too much vacuum (fouling filter) and a yellow one for
water in the bowl. You can also include different sounding piezoelectic alarms for members of your crew who will hear a buzzer and bring your attention to it. An additional bright series of lights, one located in each of the spaces in your boat, could be wired to the ground wire of your alarm lights to tell you to check the instrument panel. Also, have you tried placing your forehead against a bulkhead, from time to time, to sense the vibration of the engine? I do it all the time to "hear" stuff that is covered up with other
noise.