The marine bilge pump comes in different configurations.
A boat bilge pump can be submersible or above the water. You can have automatic bilge pumps for boats or manual bilge pumps for a boat. The bilge pump will save your life and the boat if it has a leak.
CLR Marine LLC recommends at least two bilge pumps in any small boat and more the larger the boat gets. Have the lowest marine bilge pump set up as an automatic bilge pump for your boat, this will keep the everyday rain water or sea water out of the bilge. Then have a higher marine bilge pump with a large gallon per minute (GPM) rating set up as a manual bilge pump. This manual bilge pump can be turned on in an emergency when your boat is taking on a lot of water.
Remember to always check that your marine bilge pumps are operational before leaving the dock. Those bilge pumps may save your life.