Why are submarines so slow?

Submarines are amongst the marvels of modern engineering, capable of performing a wide range of complex tasks beneath the ocean's surface. 

From stealthy reconnaissance and tactical strikes to scientific exploration and rescue missions, submarines has played critical roles in both military and civilian domains. 

However, one notable characteristic of submarines is their relatively slow speed compared to other vehicles. Typically, submarines travel at speeds of 5 to 10 knots, or about 6 to 12 miles per hour, which pales in comparison to the speed of automobiles, which can easily reach 60 miles per hour or more. There are several factors that contribute to this slower pace.

1. Stealth and Noise Considerations

One of the primary reasons for a submarine’s slow speed is its design for stealth. Submarines are engineered to operate covertly, and maintaining a low profile is crucial for evading detection. Faster speeds generate more noise due to increased water displacement and mechanical vibrations from the propulsion system. This noise can be detected by sonar systems used by other naval vessels or submarines. Consequently, submarines often prioritize stealth over speed, opting for slower, quieter operations to minimize the risk of being tracked or targeted.

2. Structural and Design Constraints

Submarines are inherently bulky due to their need to accommodate a wide array of equipment, weapons, and systems. Their design emphasizes durability and endurance rather than speed. The weight of torpedoes, missiles, sensors, batteries, and other essential equipment adds significant drag. Additionally, submarines are built to withstand the extreme pressures and low temperatures of deep-sea environments. This robust construction, while necessary for survival and operational effectiveness, also limits their maneuverability and acceleration capabilities.

3. Power Source Limitations

The type of propulsion system used also affects submarine speed. Submarines generally use either diesel-electric or nuclear power. Diesel-electric submarines require periodic surfacing to recharge their batteries, which impacts both their speed and stealth. On the other hand, nuclear-powered submarines, which can remain submerged longer, still face limitations. The propulsion systems used in nuclear submarines, while more powerful, generate heat and noise that can potentially compromise their stealth capabilities if not managed properly.

4. Operational Considerations

In addition to the structural and technological factors, operational strategies also play a role. Submarines are often used in strategic roles where speed is less critical than their ability to remain undetected and to strike or gather intelligence from advantageous positions. The slower speed allows for prolonged missions and enhances their effectiveness in these roles.

Despite their slower speeds, submarines remain invaluable assets in modern naval operations and scientific research. They conduct missions that other platforms cannot, such as deep-sea exploration, underwater data collection, and launching precision strikes. Their contributions to military strategy and scientific knowledge  demonstrates that while speed is a factor, the strategic advantages they offer often outweigh their slower pace.