Well gents you made me check my 183CX (No issues) as mine has only one inch of clearance on the top.

Now back to the issue:

A boat I use to own had the same problem your having, what I did on that boat was:

Bought a piece of pipe insulation and slid it over the divider, thus closing up the gap and away went the problem.

Attached is what I used.

http://www.amazon.com/gp/product/B000R7ZX4E

Butch