Iím assuming you are referring to the raw water engine pump; correct? If so you can pull the hose and plug it as well as lift it some. The amount of water will not be a concern of flooding the boat. Some water may come out the exit hose as well as there is standing water in the engine.
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2