What are some improvements that have been done to submarines over the years?

Answer 1

The key major design improvements to submarines since WWII are:

1. Nuclear Power - no other single improvement to submarines matches the advent of nuclear propulsion, spearheaded by Admiral Hyman G. Rickover and the design of the Nautilus. Before nuclear power, submarines weren't true submersibles - they were surface vessels that had a limited submerged attack capability. They primarily traveled on the surface, and even often attacked on the surface with deck guns rather than torpedoes against small targets of opportunity. Nuclear Power changed all that - with the ability to make fresh water, no need for refueling, and the ability to control the environment, the only limitation a modern submarine has is its crew.

2. Hull design - As I said, up to WWII, submarines were essentially surface vessels, and they were designed as such. Their design also limited their diving depth capability. The teardrop and cigar shaped hull design (spherical hulls are much stronger at deeper depths), along with innovations in hull material, dramatically increased underwater speeds. Previously, submarines could run faster on the surface than they could underwater - the opposite is true today. Submarines can run much faster underwater than they can on the surface.

3. Sonar - Though as a former Sonarman myself I'm still bound by National Security oaths, I can say that the Cold War saw the development of submarine sonar grow substantially over 30 years. In the submarine world, he who hears the other first wins, and until the John Walker spy case was broken, the NATO alliance had a clear sonar advantage over the Soviets. Walker, along with Toshiba Corp. selling key milling equipment to the Soviets that allowed them to quiet their submarine screws considerably, allowed the Soviets to achieve acoustic parity with NATO faster than they were capable of doing on their own.

4. Weapons - Submarine weapons development has increased significantly since WWII. Though torpedoes and cruise missiles were used shortly after WWII in Korea, the advent of nuclear power meant that larger boats with bigger weapons loads and capabilities could be designed. Submarines were also built as 2 separate platforms, Fast-Attack (my old domain) and Ballistic Missile. Some FBM submarines have now been converted to Cruise Missile launch platforms after the SALT II treaty was signed, and the end of USSR, and newer submarines are built with vertical launch cruise missile tubes. Longer range missiles, and improvements in torpedo guidance (acoustic and wire) make it virtually impossible for a boat with an active torpedo locked on its stern to evade it successfully.

5. Acoustic silencing - Improvements in Sonar capability are useless if your own boat is a noisemaker. The science of making submarines quieter has reached a level where they are virtually undetectable by our own boats unless at very close range (no, I can't tell you how close). However, a savvy Sonar gang can spot that as well - the ocean always has ambient background noise, and a "blank noise" spot moving through the ocean is a dead giveaway. The biggest, though not newest, development that has become standard on modern submarines are anechoic hull coatings which absorb sound and also keep internal sound from radiating further than a boat without it. The technology has been around for over 40 years, but was considered too expensive to put as standard equipment on all submarines during the Cold War as NATO knew the sonar limitations of the USSR. That strategy changed when the Soviets learned how to make their boats quieter from spy John Walker.

6. Battery Technology - While Nuclear Power is the power plant of choice for most blue-water navies, Diesel Electric boats are still used by many countries. As such, battery technology has reached a level where DE's can now remain submerged for weeks, where their WWII counterparts could only remain under for hours. Their speed is still limited by their battery though, and having to snorkel means they're a noisemaker - and a target for any nuclear submarine. It should be said though that the first thing taught in Sonar school is that there is nothing quieter in the ocean than a DE on the battery - I can attest to that fact myself.