Why are the steel pots I've usually seen on those crewing U.S. warships (especially WWII-era and beyond) so large in proportion to your basic doggie steel pot (and the wearers head)? Even when you see them with the '40's and later commo gear (huge earphones, etc.) the helmet seems way larger than it need be. Does this not make it more difficult manuvering down narrow passageways and through hatches an' stuff (I've been aboard a few, it's not like ballroom staircases in those things). What's going on under there that I'm missing?
Thanks in advance.

