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There is none, and never has been. The forward end of the floor tunnel is simply finished with a smooth slightly rounded edge. What you are seeing in your boat is the way it came from the factory.
Only the Whalers with built in tanks under the center floor tank cover had the plastic diverters.

In the case of the Montauk and smaller Whalers, it is actually good that water runs down through the tunnel. It helps keep it clear of debris and dirt. In mine, I actually spray/flush water down there occassionally to help keep it clean. All of these Whaler floor tunnels need to be flushed out once in a while.