probably have a crack in your belows, I believe it can also leak where the shift cable goes through the hull. If it is coming through the belows you need to address it ASAP because the water will ruin the u-joint and main bearing. One thing you can do to check is tilt the drive all the way up and squeeze the below and listen for air escaping, also you can usually see a stain from where the water has been leaking back out after pulling the boat out of the water.