How about an aircraft carrier made of Pykrete? It won't be fast, but you can make it big enough to carry conventional aircraft rather than dedicated carrier-based models... http://www.knowledgerush.com/kr/encyclopedia/Icecrete/
Yeah that was an interesting program on History Channel about that some time ago. Wood pulp and ice... guess they were for northern service only.. but the concept was actually sound from tests done, as to construction, floating, and durability, other than the fact it melted!!