Key Takeaways

• Diesel submarines must surface or use a snorkel to run their diesel engines, which either propel the sub directly or recharge large battery banks for underwater propulsion.
• Once submerged, the sub relies entirely on battery-powered electric motors for movement, limiting its underwater endurance.
• Nuclear-powered submarines, which do not require atmospheric oxygen for power generation, can remain submerged for weeks, offering a significant advantage over diesel-electric subs.

A dieselsubmarine is a very good example of ahybrid vehicle. Most diesel subs have two or more diesel engines. The diesels can runpropellers or they can rungenerators that recharge a very largebattery bank. They can also work in combination, one engine driving a propeller and the other driving a generator.

The sub must surface (or cruise just below the surface using a snorkel) to run the diesel engines. Once the batteries are fully charged, the sub can head underwater. The batteries powerelectric motors that drive the propellers.Battery operation is the only way a diesel sub can actually submerge.

The limits of battery technology severely constrain the amount of time a diesel sub can stay underwater. This is the huge benefit of using nuclear power in a sub. Nuclear generators need no oxygen, so a nuclear sub can stay underwater for weeks at a time. SeeHow Nuclear Power Works for a description.

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