Diesel-electric subs are quieter while running in electric mode, but must at some point surface or pop up a snorkel to run their diesel engines and recharge the batteries. When the diesel engines are running, these noisier than nuclear-powered subs.
Are nuclear submarines quieter?
Nuclear-powered submarines can stay quieter for longer. To put it simply, nuclear-powered submarines are often quieter than diesel-powered alternatives.
Are diesel submarines quieter?
The diesel submarines of today are not those of the days of the USS Nautilus. They operate much more quietly on new-generation diesel engines with advanced batteries. … Nuclear submarines require large reduction gears and a robust cooling system to maintain safe operation of the reactor.