Xpress XP18CC Open Outer Hull Seam

[ratherbefishing186]

Can someone please explain to me why the seam between my main hull and the outer rail around my boat is open? The gap is slight maybe 1/8" but when I am running water splashes up into this seem and enters my hull. I have to hit my bilge occasionally when im running and when i stop to clear it all out. I plan to seal up next week with some marine silicone or something, but just cant for the life of me understand why it would be designed like that.