The I-400 actually had 2 x pressure hulls, laid side by side so as to form a binocular shape in cross section. This accounts for the broad beam of this beeste. The crane was, in all likelihood, set outside of the pressure hulls, (in the ballast spaces) as there would be no need to deploy it while submerged.
I actually do not have a hot clue how this crane actually operated and whether it was periscope-like or not. I noodled it up so as to be "semi-retractable" and "semi- stowable". The dimensions of the "crane tub" on the model suggest that I might well have been wrong. Ca va la vie!
I needed to be able to retract/ stow the crane for further "photo opps"!
MTF!
Jim
Wilfried, Robert,Reuben, Chuck, Marco,Treadhead, Simon etc: Thanks for the encouragement and suggestions!! "If your friends are there, then everything's all right" --The Who
Maj. Charles: Re "piece of work": I know a few people who might be UN-charitably described thus!! Some of these, I was even married to...
Hence, my caution!!