Carbon fiber is the dark grey weave shown in the stripes here in both the hull and deck on either side of the metal rub rail on this boat.
Carbon Fiber fabric adds stiffness and strength in a boat like few other fiberglass fabrics will. FRP (fiberglass reinforced plastic) boat hulls and decks are a combination of fiberglass fabric and resin laid up in a boat mold together.  You can change the resin and the fabric that is used in a given boat to obtain different strengths and other features.
The builder of this boat said to seabuddy that between the amount of skilled labor (five men at one point in time) and the fabric cost that he ended up doing this boat owner more of a favor, rather than making a fair profit at his “under $10,000” option charge.
The weave in this boat is protected and shows through its clear gelcoat finish.
Here is a link to more about carbon fiber in boats…

http://www.jamestowndistributors.com/userportal/show_product.do?pid=6158&BASE

and here…

http://blog.jamestowndistributors.com/?p=877