This file package includes many upgrades that were drafted by Bill DiMartino to go with the superb USS Nautilus SSN571 file set also offered here on the Nautilus Drydocks: 
https://www.rc-submarine.com/product-page/uss-nautilus-ssn571-stl-file-package
 
File package includes: 
Accessories and Misc
hollow masts
tie down parts 
modified rudders
full deck pieces
hull joiners
modified dive planes
Full functional bow plane retract mechanism
Full functional torpedo shutters
Modified hull and WTC support hardware
Improved stern access alternative parts
Improved sail with nave lights and flag post