[C320-list] Water

[Dave Hupe]

 Sounds like you already ruled out a leak at the emergency tiller hatch when you say the steering was dry.  However, open that hatch and make sure you don't have a puddle on the steering quadrant.  If you do, replace the hatch/port.  The next thing I suggest you check is a leak around the pan for the propane tank. That seal on my boat was really dried out and badly leaking during a storm. I pulled out the pan and redid the seal pretty easily.  Those 2 items constituted big leaks for me when I first bought our boat …… bone dry now. 
However, I'm a little confused what you are describing.  You consistently say the bilge is dry.  Water is showing up only directly under the floor boards just below your companionway (on top of the flat fiberglass  in front of the engine) ? This definitely sounds like at leak at your companionway hatch boards or the overhead sliding hatch.  But if that is the case, you should see water on top of the floor boards. 
Dave Hupe 
1994 Cat 320 (#32) "Mayan Sun"
Holland, MI