Hi Frank: No direct experience with these shaft-mounted pumps, but they appear to me to be one hell of a clever idea. There are several issues to consider. How high does the water level have to rise before the pump starts to work, and how much flooding does that represent? On modern, light displacement and/or flat-bottomed boats it is likely the shaft would be quite high and there could be a problem with the engine’s v-belts flinging water around, shorting out electrics, etc. However, on a deeper bilge design, especially one where the prop shaft exits low relative to the rest of the engine, I think these could be ideal. Otherwise, a pump which allows a hose to be run to a low point is probably safer. Steve

PS: keep in what the heeled flood level looks like as well as that when the boat is upright.