Here's a copy and paste from the web site article on the Standard Rules:

"During the Combat phase, when a ship fires on another ship, place the target ruler on the central firing cone on the shooting side of the firing ship, and measure to the main mast of the targeted ship. If the ruler passes through the short side of the target base (either the front one or the rear one), it’s a raking shot,"
There are three arcs on each side of the ship. This implies you can only get a rake with the center arcs on either side. Would you interpret it that way as well?