The boat is not water tight from above!
Luckily, it is from below. Other sources of casual water in my H23 are: 1) The front hatch (you may have some water under the V-berth); 2) The anchor well (may need to check the hose and clamps on the drain); and 3) Water backing up under the companionway hatch. (The traveler track on my boat is solid, and the only way for rain water to drain from behind it is two small channels molded into the fiberglass. If those channels become clogged with dirt or debris, or if it is an exceptionally hard rain, water will back up and spill into the cabin before it overflows the traveler track. I have considered drilling some drain holes in the track, but haven't yet).