At that time not only Japanese and Germans were crazy about sizes, the Brits had their own project (never keel laid), the HMS Habakuk, a roughly 2.200.00 (!) tn ship built from
pykrete, a kind of slow melting ice made from a mixture of 14% wood pulp and 86% water.
The idea was to build a super carrier that would be the base for U-Boat hunt in the Atlantic (the project was abandoned when the Azores served this purpose), insulated by vast amont of cork. It wouldhave been 100okg bomb proof, and easily repaired with ... water
Steam turbogenerators were to supply 33,000 hp (25,000 kW) for 26 electric motors mounted in separate external nacelles (normal, internal ship engines would have generated too much heat for an ice craft). Its armament would have included 40 dual-barrelled 4.5" DP (dual-purpose) turrets and numerous light AA guns, and it would have housed an airstrip and up to 150 twin-engined bombers or fighters.
Top speed 6 knots:
http://funkoffizier.wordpress.com/2007/09/13/proyecto-habbakuk-el-portaaviones-de-hielo/
Rattler