Our boat has a SLOW lEAK AT THE PROPELLER SHAFT. The picture included shows the location of the leak. I attempted to tighten the conection around the shaft, but it seemed locked in place. The leak increases when we run the engine at higher speeds. It fills the small bilge on our oday 25 in 24 hours. Any suggestions on how to fix it would be a great help. Should I work harder to tighten it or life caulk or other ideas. Thank you for the help.