What I would do if u want to start the boat out of water and not take apart the drive line ..... is take a hose and stick it in the end of the pump. Put the boat in reverse so the hose stays put and turn it on. This will wash the pump free from dirt and keep it cool wwhile running. You will also need a second hose to hook to the motor if u run it long.
......every one has there own way. Hope this helps