Don't cut it out yet to make it easier to scribe the grid lines. Carefully scribe lines approximately one scale inch apart across the deck layout. Now scribe across those lines with lines approximately three scale inches apart. After all lines are scribed go ahead and cut the deck out. Brush on some enamel paint, being sure to get it down in the scribe lines and then use a rag with a little mineral spirits to remove the excess, leaving the paint down in the lines.
Reason being, on the prototype they can see down through the deck.
When the long line run horizonal to the pilot house, they can't see through the deck. It appears as a solid deck. See examples below on prototypes. View of mv. A fleet deck built the wrong way.