Hi Martin, that is a good question and have wondered that myself. This huge exhaust stack seemed out of place. The only thing I could find out on her history was that she had 16 boilers providing steam for her electric turbines. There had to have been alot of stack pipe venting, all going up one side of the ship. Unlike the USS Ranger CV-4 I am starting, which had her three stacks on each side exiting the upper sides of the flight deck and being able to pivot down while flight ops were in progress. Not the case with the Lexington. So, they had to hide and streamline those stacks somehow and that's what they did. Mind you, the Lexi was a converted Battle Cruiser hull to aircraft carrier, where-as the Ranger was built from the keel up as an aircraft carrier. We are talking an evolutionary process here in ship design and I will talk about and you will see on my next build project how the Ranger, which was in a class all its own, more like the USS Langley in design, but with an Island added later on. Stay tuned. Dennis