I bought 12v submerge bilge pumps off Aliexexpress and switch them with a Waterwitch switch.
www.whitworths.com.au/water-witch-electronic-bilge-switch I bought two and just replaced one a couple of days ago. They are cheap enough to buy two or three at a time and carry a spare. The quality is excellent and the one that failed had the impeller come off the shaft. I put the impeller back on and ground and roughened the centre up and put a drop of JB-Weld on and it's now the spare. I shall buy a couple more though just in case.