[igotpron]

I'd inspect the drive well thoroughly. Inside and out, stick your head inside the boat and really look for a crack. If you had yor hatch liner in water from the front hatch shouldn't of leaked into the hull. Another thought might be your back round hatch has a leak and your tank was just draining into it. And finally make sure your drain plugs were in, and tight.

And for "testing" I would hook up the air compressor with a really low amount of pressure and look for possible air escaping. Should be able to rig some sorta hose and duct tape contraption to the drain plug.