The question of whether a submarine is affected by a storm depends entirely on its depth. Submarines are highly specialized vessels designed to operate in two very different environments: on the surface like a normal ship or deep beneath the waves. While a severe storm presents an existential threat to a surfaced submarine, submerging quickly transforms the vessel into one of the safest places in the ocean. The physics of how wave energy travels through water dictates this difference in experience.
Physical Effects When Surfaced
Submarines encounter significant danger when operating on the surface during a storm, such as when transiting or snorkeling for air. Unlike surface ships, which have a broad beam and a deep keel for stability, a submarine’s cylindrical hull is designed for deep-water pressure. This design gives it poor stability characteristics on the surface, leading to extreme pitching and rolling in high seas that are far more violent than on a conventional vessel.
Severe motion makes it difficult for the crew to move safely and perform tasks. The submarine’s sail, or conning tower, is subjected to immense structural stress as it is repeatedly pounded by waves. The danger is compounded by “green water,” which is the term for solid sheets of ocean water crashing over the hull and sail. Green water can strip equipment from the weather decks and poses a severe risk of injury to personnel on watch.
The Physics of Depth and Wave Energy
A submarine escapes the violence of a surface storm by exploiting the physics of wave energy dissipation. Ocean waves, even massive ones generated by a hurricane, are primarily kinetic energy concentrated at the air-water boundary. This energy does not extend indefinitely downward but fades rapidly with depth in an exponential decay pattern.
The circular motion of water particles that creates a surface wave becomes smaller as the depth increases. This wave energy effectively disappears once the submarine descends below the wave base, which is half the distance of the wave’s length. For most storm-driven waves, the turbulent effects become negligible below a depth of approximately 100 to 200 meters. Even in the most violent storms, the deepest felt effect rarely extends beyond 400 feet, which is well above the normal operating depth of a modern submarine.
Operational and Communication Challenges
While a submerged submarine is physically protected from the storm’s mechanical force, the severe weather still creates significant operational challenges. Communication with shore command becomes much harder because the submarine must remain deep to avoid the surface turbulence. Standard radio frequencies cannot penetrate far into seawater, forcing the vessel to rely on extremely low frequency (ELF) or very low frequency (VLF) signals.
These lower frequency signals can reach a submerged submarine, but they carry data at an extremely slow rate, often only a few characters per minute. To receive high-bandwidth communications, the submarine must ascend to periscope depth and deploy an antenna mast. This procedure is highly dangerous and difficult in violently churning surface waters. Furthermore, the inability to safely raise the periscope or other masts prevents the crew from taking celestial navigation fixes, complicating the determination of the vessel’s precise location.
Storm Noise and Acoustic Cloaking
Paradoxically, the storm’s intense surface activity can provide a tactical advantage for the submerged vessel. The constant churn, heavy rain, and crashing of waves create a tremendous amount of ambient noise in the upper layers of the ocean, often referred to as “sea state noise.” This high level of background noise acts as a form of natural acoustic cloaking for the submarine.
The noise effectively masks the vessel’s own sound signature, making it much harder for passive sonar systems to detect the submarine’s machinery and propeller sounds. However, this same high noise level simultaneously hinders the submarine’s own passive sonar capabilities. The vessel’s listening equipment struggles to distinguish distant, quiet targets from the surrounding environmental roar. The acoustic environment during a storm is a double-edged sword, providing stealth but at the cost of situational awareness.