During the 1930's when other navies were upgrading their facilities, the Empire had little reserves for the Navy to upgrade its infrastructure, most of the Imperial War Budget had been spent on the Army and creating the Army and Navy Air forces. The largest building docks available could handle ships no more than 790 feet in length. This length was fine for the Treaty battleships and the Yupanqui class showed what could be done. However the aircraft carrier was a different beast. The CV required as much hull volume as possible for their main task of housing, feeding, launching and recovering aircraft. The Incan designers wanted to build the biggest aircraft carrier they could but were limited by the docks available. With the Yupanqui class under construction only two slightly smaller docks were available until the new 1100 foot docks that were to be constructed were completed. The Imperial designers were nothing if not innovative. By collapsing the wall between two of the smaller docks a catamaran hull could be built. The cat-a-carrier was born.
There are so many things for and against this design. I am sure everybody will want to make a comment telling me why it will either work or not work. I have done this as a semi-serious bit of work and my apologies to Bombhead who's nice drawing I have butchered.
You will note from the bottom drawing that I have shown the anchor points of the catamaran 'join' between the hulls.