Many offshore boats are fitted with some kind of high capacity emergency bilge pump, sometimes known as crash pumps. We have long considered one for Morgan’s Cloud but have shied away because we don’t like cluttering up the main engine with belted devices and we have yet to find a pump that is compact enough to fit, will run dry—in a flooding situation we would not have time to monitor the pump and shut it down the minute it sucks dry—and handle the kind of trash that will almost inevitably be floating around in a badly flooding boat.
I think we have found the answer on Polaris: She is equipped with two 220 volt (also available in 110 volt) high capacity household sump pumps that will move a huge amount of water and munch up just about anything thrown at them. These pumps are readily available, relatively cheap, can be placed wherever needed (even to help another boat) and be powered by our generator or inverter. Of course we would have to be very careful with such voltages around water. Also, if the generator and inverter get flooded, we would be back to our massive Edson manual pump, but then the same is true of engine driven pumps.