What If The Thresher Submarine Never Sank?

The Actual History

On April 10, 1963, the USS Thresher (SSN-593), the lead vessel of the United States Navy's revolutionary Thresher-class nuclear-powered attack submarines, sank during deep-diving tests about 220 miles east of Cape Cod, Massachusetts. All 129 personnel aboard—comprising 112 naval officers and crew plus 17 civilian technicians—perished in what remains the deadliest submarine disaster in U.S. naval history.

The Thresher represented the cutting edge of submarine technology when commissioned in 1961. As the first of a new class designed specifically to counter the growing Soviet submarine threat, she embodied significant advances in naval engineering. The submarine featured a hydrodynamic teardrop hull design that enhanced underwater speed and maneuverability, reinforced HY-80 steel construction allowing for greater operating depths, an advanced sonar system providing superior detection capabilities, and quieting technologies that dramatically reduced her acoustic signature. With these innovations, the Thresher could operate deeper, faster, and more quietly than any previous submarine, giving the U.S. Navy a decisive advantage in undersea warfare capabilities.

On the morning of her loss, the Thresher was conducting post-overhaul sea trials accompanied by the submarine rescue vessel USS Skylark. After completing initial shallow dives, the submarine began a carefully controlled descent to her test depth of 1,300 feet. At approximately 9:13 AM, the Skylark received a garbled underwater telephone message indicating the Thresher was "experiencing minor difficulties" and was attempting to blow her ballast tanks to surface. This was followed by the sound of compressed air, then silence. Despite extensive search efforts, the submarine was never seen again.

The Navy launched an immediate Court of Inquiry investigation. Subsequent analysis, including examinations of debris recovered from the ocean floor, concluded that the most likely cause was a failure in the submarine's seawater piping system. Investigators theorized that a silver-brazed pipe joint in the engine room failed under the immense pressure at test depth, allowing seawater to spray onto electrical panels and trigger a reactor scram (emergency shutdown). Without propulsion, the submarine would have continued to descend. When the crew attempted to blow the ballast tanks to surface, moisture in the high-pressure air system likely froze in the valves and restricted airflow, preventing the submarine from arresting her descent. As Thresher passed below crush depth, her hull collapsed catastrophically within milliseconds.

The loss of the Thresher sent shockwaves through the Navy and the nation. In direct response, the Navy established the SUBSAFE quality assurance program in December 1963. This comprehensive overhaul of submarine design, construction, and maintenance standards focused on systems critical to recovering from flooding casualties and maintaining watertight integrity. SUBSAFE implemented rigorous testing requirements, material standards, and documentation protocols. Since its implementation, only one U.S. Navy submarine, the USS Scorpion (SSN-589) in 1968—which had not yet completed SUBSAFE certification—has been lost.

The Thresher disaster also led to the development of the Deep Submergence Rescue Vehicle (DSRV) program and other enhanced submarine rescue capabilities. The tragedy fundamentally transformed submarine safety culture, establishing protocols and standards that continue to influence naval operations worldwide to this day.

The Point of Divergence

What if the USS Thresher never sank on that fateful April morning in 1963? In this alternate timeline, we explore a scenario where America's most advanced nuclear submarine survived its deep-diving tests, avoiding the worst submarine disaster in U.S. naval history and potentially altering the course of Cold War naval development.

Several plausible divergences could have prevented the catastrophe:

Enhanced Pre-Trial Inspections: In this scenario, a more thorough quality control inspection during the Portsmouth Naval Shipyard overhaul might have identified the faulty silver-brazed pipe joint before sea trials began. Perhaps a particularly meticulous inspector noticed inconsistencies in the documentation of welding certifications, prompting additional testing of critical pipe joints. This extra scrutiny could have revealed the substandard joint that ultimately failed under pressure in our timeline.

Improved Moisture Control: The Thresher's high-pressure air system contained moisture that likely froze in the valves when the emergency blow was attempted, preventing sufficient air from reaching the ballast tanks. In this alternate timeline, improved moisture separation equipment might have been installed during the submarine's nine-month overhaul, or protocols for purging moisture from the system could have been more effectively implemented before the deep dive.

Altered Test Parameters: Perhaps in this alternate history, weather conditions or minor mechanical issues caused the deep-diving test to be postponed or conducted in a modified sequence. This delay might have provided additional time to discover latent problems with the submarine's systems before subjecting them to extreme depths.

Different Emergency Response: When the initial pipe failure occurred, the submarine's crew might have responded differently in our alternate timeline. Perhaps the reactor operator managed to maintain emergency propulsion rather than executing a full scram, giving the submarine enough power to control its depth until repairs could be implemented.

In each of these scenarios, the USS Thresher completes its sea trials successfully and returns to active service, taking its place as the lead vessel of America's most advanced submarine class. The 129 men aboard survive, and the U.S. Navy continues its undersea Cold War operations without the transformative shock that reshaped its approach to submarine safety in our timeline.

Immediate Aftermath

Continued Thresher-Class Production

Without the catastrophic loss of the USS Thresher, the Navy's submarine construction program would have continued without the significant disruptions and reassessments that followed the disaster in our timeline:

Accelerated Production Schedule: The production of Thresher-class submarines (later renamed Permit-class in our timeline) would likely have proceeded at a faster pace. In actual history, construction was temporarily halted for safety reviews following the disaster. In this alternate timeline, the planned fleet of 25 Thresher-class submarines might have been completed closer to the original schedule, providing the Navy with enhanced anti-submarine warfare capabilities earlier in the Cold War.
Evolutionary Rather Than Revolutionary Design Changes: Without the hard lessons learned from the Thresher disaster, subsequent submarines of the class would likely have featured more gradual improvements rather than the substantial safety overhauls implemented after the sinking. The original designs for systems like the emergency blow capability and electrical insulation would have evolved more slowly through routine refinement rather than comprehensive redesign.
USS Thresher as Operational Leader: As the lead ship of her class, the Thresher would have served as a testing platform for new technologies and tactics. Her experienced crew would have developed and refined operating procedures for this new generation of submarines, potentially accelerating tactical innovations in undersea warfare.

Delayed Development of Safety Standards

The absence of the Thresher disaster would have significantly impacted submarine safety protocols:

No SUBSAFE Program: The comprehensive SUBSAFE quality assurance program, implemented directly in response to the Thresher sinking, would not have been established in 1963. Instead, submarine safety standards would have continued to evolve incrementally, likely guided by minor incidents and near-misses rather than catastrophic failure.
Different Prioritization of Resources: Without the urgent mandate for safety improvements, the Navy would have likely continued to prioritize performance capabilities over redundant safety systems. Budget allocations would have favored weapons systems, propulsion improvements, and acoustic quieting rather than enhanced emergency systems and material quality control.
Potential for Additional Incidents: The absence of stringent SUBSAFE standards might have increased the likelihood of other submarine accidents in the late 1960s and 1970s. The loss of USS Scorpion in 1968 might still have occurred, but without the context of the Thresher disaster, it might not have prompted the same level of comprehensive safety review.

Shifted Cold War Naval Operations

The USS Thresher's continued service would have immediately influenced Cold War naval operations:

Enhanced Anti-Submarine Capabilities: With its advanced sonar systems and quiet operation, the Thresher would have been immediately deployed to track Soviet submarines, particularly the new Hotel-class and Echo-class nuclear submarines that were entering service in the early 1960s. The intelligence gathered from these operations might have provided earlier insights into Soviet naval capabilities.
Submarine Intelligence Missions: The Thresher would likely have been assigned to sensitive intelligence-gathering missions, potentially including cable-tapping operations like those later conducted by the USS Halibut under Operation Ivy Bells. Her advanced capabilities would have made her ideal for covert operations in Soviet waters.
Impact on Soviet Naval Development: The Soviet Navy would have observed the continued success of the Thresher class and potentially adjusted their submarine development programs in response. Without the pause and reflection caused by the Thresher disaster, the pace of the undersea technology race might have accelerated in the mid-1960s.

Personal and Organizational Impact

The survival of the Thresher would have had profound effects on the people involved and the naval organization:

Career Trajectories: The 129 men who perished with the Thresher in our timeline would have continued their naval and civilian careers. Some officers, like Lieutenant Commander John Wesley Harvey (the Thresher's commanding officer), might have risen to significant leadership positions within the submarine force, potentially influencing later submarine design and operational doctrine.
Different Institutional Memory: The U.S. Navy's submarine force would have developed a different institutional ethos without the sobering influence of the Thresher disaster. The culture might have continued to emphasize daring and technological superiority over caution and redundancy, potentially leading to different approaches to risk management in submarine operations.
Portsmouth Naval Shipyard: Without the shadow of the Thresher disaster, the reputation of Portsmouth Naval Shipyard would have remained untarnished. The yard would have continued its submarine overhaul and repair operations without the intense scrutiny and procedural overhauls that followed the disaster in our timeline.

The immediate years following the Thresher's successful deep-diving tests would have seen a U.S. Navy submarine force growing in confidence and capability, untempered by the harsh lessons of disaster. This confidence would shape the evolution of submarine warfare throughout the remainder of the 1960s, setting the stage for different long-term developments in naval technology and doctrine.

Long-term Impact

Evolution of Submarine Design and Safety

Without the catalyst of the Thresher disaster, submarine design philosophy would have followed a significantly different trajectory over the subsequent decades:

Delayed Safety Integration: The comprehensive safety systems that became standard in post-Thresher submarine designs would likely have been implemented more gradually and inconsistently. Systems like emergency blow capabilities, hull integrity monitoring, and flooding detection might have been incorporated piecemeal rather than as part of a unified safety framework.
Performance-Oriented Design Philosophy: Submarine designs through the 1970s and 1980s would have continued to prioritize tactical performance—speed, depth, acoustic signature, and weapons capacity—potentially at the expense of redundant safety systems. The Los Angeles-class submarines, begun in the early 1970s, might have featured even more aggressive performance specifications but fewer of the safety-oriented design elements that characterized them in our timeline.
Eventual Safety Reckoning: Without SUBSAFE's preventative influence, it's probable that another serious submarine incident would have occurred by the 1980s, potentially involving a more modern submarine with a larger crew. Such a disaster might have finally triggered the comprehensive safety reforms that the Thresher incident prompted in our timeline, but decades later and potentially after additional loss of life.

Impact on Cold War Naval Strategy

The continued operation of the Thresher and uninterrupted development of subsequent submarine classes would have influenced Cold War naval strategy in several ways:

Accelerated Undersea Arms Race: With the U.S. submarine force maintaining its technological momentum unbroken by the Thresher disaster, the undersea arms race between the United States and Soviet Union might have intensified earlier. Soviet designers would have faced increased pressure to match the capabilities of the continuously improving American submarine fleet.
Different Deployment Patterns: The availability of additional attack submarines might have allowed for more aggressive forward deployment strategies against Soviet bastions. Areas like the Barents Sea and Sea of Okhotsk might have seen more frequent penetration by American submarines, potentially increasing tensions but also gathering valuable intelligence.
Submarine Force Structure: By the 1980s, the U.S. might have operated a larger submarine fleet than in our timeline, with resources allocated differently between ballistic missile submarines and attack submarines. The earlier maturation of submarine technology might have influenced the balance between quality and quantity in force planning.

Technological Development Pathways

The absence of the SUBSAFE program would have altered the landscape of undersea technological development:

Commercial Crossover: The stringent quality control standards developed under SUBSAFE influenced commercial marine engineering and even industries like aerospace and nuclear power. Without this program, the cross-pollination of safety-oriented engineering practices might have developed more slowly or followed different pathways.
Underwater Rescue Capabilities: The Deep Submergence Rescue Vehicle (DSRV) program, accelerated after the Thresher disaster, might have developed more slowly or with different priorities. International submarine rescue standards and cooperation agreements might have evolved differently without the impetus of the Thresher tragedy.
Materials Science Applications: The intensive focus on material reliability that followed the Thresher disaster drove advances in non-destructive testing, welding standards, and material certification. These advances might have occurred more gradually or been driven by different imperatives in our alternate timeline.

Geopolitical Implications Through the End of the Cold War

As the Cold War progressed through the 1970s and 1980s, the divergent submarine development would have had cascading effects:

Naval Arms Control: Submarine capabilities might have featured more prominently in arms control negotiations of the 1970s and 1980s. Without the Thresher disaster highlighting the inherent dangers of undersea operations, there might have been less appreciation for the risks of the undersea arms race, potentially complicating naval arms limitation efforts.
Crisis Management: During tense Cold War episodes like the 1973 Yom Kippur War, when U.S. and Soviet naval forces operated in close proximity, different submarine capabilities and operating procedures might have altered crisis dynamics, potentially increasing risks of unintended escalation.
Intelligence Collection Advantages: The potential deployment of more advanced submarines earlier might have provided the U.S. with greater intelligence collection capabilities against Soviet naval forces, potentially providing earlier warning of Soviet naval developments and possibly influencing strategic assessments.

Post-Cold War Submarine Development

Following the end of the Cold War, the alternative development path would continue to influence submarine forces into the 21st century:

Different Seawolf and Virginia Programs: The Seawolf-class submarines, designed as Cold War apex predators, and the subsequent Virginia-class submarines might have evolved differently in terms of safety systems, construction standards, and operational capabilities. Without SUBSAFE's half-century of influence, these designs might have emphasized different trade-offs between performance and safety.
Nuclear Submarine Proliferation: Safety standards for nuclear submarine operation influence which nations can realistically operate such vessels. Without the high bar set by SUBSAFE, nuclear submarine technology might have proliferated more widely to second-tier naval powers, potentially creating additional nuclear safety and security concerns.
Contemporary Submarine Culture: The culture of submarine forces worldwide has been shaped by the lessons of disasters like the Thresher. Without this formative tragedy, the safety-conscious, methodical approach that characterizes modern submarine operations might have developed differently, potentially retaining more of the daring but risk-prone culture of earlier submarine eras.

Environmental and Public Perception Impact

The absence of the Thresher disaster would have influenced public and political perceptions of nuclear submarine programs:

Public Confidence: Without major submarine disasters attributed to technical failures, public confidence in nuclear submarine programs might have remained higher through the environmentally conscious 1970s and the anti-nuclear 1980s, potentially leading to stronger political support for expanded submarine programs.
Nuclear Safety Perception: The Thresher disaster, while not involving a release of radiation, nevertheless influenced perceptions about the safety of nuclear naval propulsion. In its absence, concerns about nuclear submarine safety might have focused more on theoretical risks rather than actual disasters, potentially leading to different regulatory approaches.
Budget Priorities: Without the expensive implementation of SUBSAFE standards, more defense funding might have been available for expanding the submarine fleet or developing advanced weapons systems, potentially leading to different force structures by the 2000s.

By 2025 in our alternate timeline, the U.S. submarine force would be operating with different safety standards, potentially different technologies, and certainly a different institutional memory and culture. While many of the same technological developments would likely have occurred eventually, the path to get there—and the balance between performance, safety, and cost—would reflect the absence of the harsh lessons learned from the USS Thresher's loss.

Expert Opinions

Dr. Norman Friedman, Naval Historian and Author of "U.S. Submarines Since 1945," offers this perspective: "The loss of Thresher created a watershed moment in submarine development that's difficult to overstate. In a timeline where she survived, we would almost certainly have seen a more gradual evolution of safety standards rather than the revolutionary SUBSAFE program. The Navy likely would have continued prioritizing performance metrics like speed and depth over redundant safety systems. I believe we'd have eventually seen another major disaster, perhaps involving a Los Angeles-class boat in the 1970s or 1980s, which would have then triggered the reforms we implemented earlier in our timeline. The question isn't if a similar safety regime would have eventually emerged, but rather how many more lives might have been lost before it did."

Vice Admiral James Caldwell Jr. (Ret.), former Director of Naval Nuclear Propulsion, provides this assessment: "Without the Thresher catalyst, submarine force culture would have developed along significantly different lines. The methodical, questioning attitude that defines modern submarine operation was forged in the crucible of that disaster. In an alternate timeline, I suspect we'd have maintained more of the swashbuckling, risk-tolerant approach of the early nuclear navy. This might have accelerated certain technological developments by accepting greater operational risks, but at a potential cost in lives and vessels that would have been unacceptable. The meticulous material control and quality assurance that defines nuclear submarine operations worldwide today might be less universal, potentially leading to more incidents among emerging submarine powers who might have adopted less rigorous standards."

Dr. Katherine Epstein, Professor of Naval History at Rutgers University and author of "Torpedo: Inventing the Military-Industrial Complex in the United States and Great Britain," suggests: "The absence of the Thresher disaster would have had complex implications for the military-industrial relationship in submarine construction. SUBSAFE fundamentally altered how the Navy approached contractor oversight and quality control. Without this program, we might have seen a more adversarial relationship develop between the Navy and shipbuilders as problems emerged piecemeal rather than being addressed systematically. The intensive focus on material science and non-destructive testing that emerged from SUBSAFE had wide-ranging implications beyond submarines, influencing everything from commercial shipping to aerospace. These advances might have occurred eventually through other channels, but their development and implementation would likely have been more fragmented and industry-specific, without the driving force of preventing another Thresher-type disaster."