The Death of the Titan
On June 18, 2023, the Titan submersible, persistently but completely incorrectly referred to in the media as a "bathyscaphe" (journalists, learn your stuff!), perished in the Northwest Atlantic at a depth of approximately 3800 meters. The five people on board perished along with it.
Numerous media reports and videos have appeared about this event, but most are untrustworthy, and their authors are unfamiliar with the subject. Therefore, we will turn to a reliable source.
On August 4, 2025, the United States Coast Guard (USCG) released the results of its investigation into the circumstances and causes of the incident: “Report of the Marine Board of Investigation Into the Implosion of the Submersible TITAN (CG1788361) in the North Atlantic Ocean Near the Wreck Site of the RMS TITANIC Resulting in the Loss of Five Lives on June 18, 2023.”
In this article I will try to briefly outline the contents of this document, I think that it will be of interest not only to specialists, but also to fans of marine technology and its stories.
OceanGate Inc., a privately held American company based in Everett, Washington, was founded in 2009 with the initial goal of creating a small fleet five-seater commercial underwater vehicles that would be rented to organizations or individuals for scientific research or tourism.
The company acquired its first manned submersible, the Antipodes (with a diving depth of 305 meters), in 2010. Between 2010 and 2013, the vehicle conducted approximately 130 dives, with each underwater tourist paying between $7500 and $40000. In 2018, OceanGate put the Antipodes up for sale.
In 2012, Boeing and OceanGate signed an agreement to conduct a preliminary feasibility study for the CYCLOPS submersible concept, featuring a robust hull made of carbon fiber composite and titanium. On October 21 of the following year, Boeing presented a report on the results of the work performed in accordance with the customer's requirements (operating depth of up to 8600 m, robust hull made of composite materials).
With an operational diving depth of 8600 meters and a safety factor of 1,5, the wall thickness of the cylindrical pressure hull, made of carbon fiber composite, was required to be at least 81,3 mm. The report specifically noted that one of the most critical components of the design is the adhesive bond between the composite hull and the titanium segments.
Surface preparation was critical, and little was known about the bond strength of titanium and carbon fiber. While shear strength may be less critical due to compressive loads at the bond line, compressive loads at depth will be higher than those typically observed in adhesive bonds. The report emphasizes the need for further research to understand how this type of bond behaves under these conditions and how applied loads affect the adhesive bond.
Conceptual image of the deep-sea vehicle "Cyclops" (Boeing)
In 2015, Cyclops 1 (with a diving depth of 500 meters), developed by OceanGate in collaboration with Washington State University and Boeing, entered service. Both Antipodes and Cyclops 1 had a pressure steel hull. They were followed by Cyclops 2, later renamed Titan.
Antipodes
Cyclops 1
Let's start with the technical description of Titan. It was developed by OceanGate in collaboration with NASA, Washington State University, and Boeing and became operational in 2018. The cost of designing, building, and testing the vehicle was approximately $5 million.
Initially, the submersible's robust hull was planned to be constructed entirely of carbon fiber. In 2015-2016, a series of tests were conducted on 1:3 scale models. These tests revealed the unreliability of the carbon fiber spherical ends, so the decision was made to manufacture them from titanium.
Damage to the carbon fiber spherical end of the Titan model (marked in red). Depth: 2943 m
One of the models destroyed during testing
During model tests, the maximum safe diving depth achieved was 4200 m, which is 4400 m less than planned.
The carbon fiber pressure hull was manufactured by Spencer Composites from March to October 2017. Its length was 2540 mm, its outside diameter was 1676 mm, its operating pressure was 464 kg/cm², its safety factor was 2,25, and its weight was 2722 kg.
The construction process utilized alternating impregnated carbon fibers and unidirectional epoxy fabrics in the axial direction, as well as wet circular winding of carbon fiber and epoxy resin. Grafil 37-800 carbon fibers, Epon Resin 682 epoxy resin, and Lindride LS-81K hardener were used. The structure consisted of a total of 480 layers, with a hull wall thickness of 127 mm. The hull was formed on a stainless steel mandrel. To protect against seawater, the hull was coated externally with a 5 mm layer of polyurethane, and a fiberglass insert was installed internally, preventing moisture condensation but preventing visibility of the composite portion of the pressure hull.
In the optimized design presented in Boeing's feasibility study, the carbon fiber body thickness was 7 inches. However, OceanGate reduced this thickness to 5 inches for the final Titan design, with the key difference being the exclusion of 45-degree plies from the final carbon fiber layup. Boeing's preliminary report indicated that deformation tolerance tables did not support layup patterns without 45-degree plies. Despite this, the final Titan design used only circumferential and axial plies of carbon fiber, but none of the project participants interviewed by MBI could explain why the 45-degree plies were excluded.
Winding carbon fiber onto a mandrel
Removing the mandrel
In 2021, due to the appearance of fatigue cracks in the composite part of the pressure hull, it was replaced.
Following replacement of the composite portion of the pressure hull, it was tested at the Deep Ocean Test Facility in Bethesda, Maryland, in March 2021. The maximum depth reached during testing was 4200 m.
Titan during testing
The titanium hull components (Grade 3 titanium, with a tensile strength of approximately 480 MPa) were manufactured by Titanium Fabrication Corp. The bow and stern titanium hemispheres were 1524 mm in diameter and 83 mm thick. The ends of the composite pressure hull were bonded to titanium rings, to which the hemispheres were bolted. The 1680 kg bow hemisphere, which could be folded to the right for crew embarkation and equipment loading, had an opening for a 318 mm diameter window.
Nasal hemisphere
A titanium ring with epoxy adhesive is installed on a composite part of a robust housing
HYSOL® EA 9394, a two-component epoxy adhesive also known as LOCTITE® EA 9394 AERO, was used for bonding. This adhesive was applied to the carbon fiber hull ends and to the C-shaped grooves in the fore and aft titanium rings. The C-shaped profile measured approximately 35 mm deep and 127 mm wide, tapering slightly at a depth of 122 mm into the recess.
C-shaped groove in a titanium ring
Folding nose hemisphere
Four so-called “penetrators” were attached to the aft hemisphere, serving for the hermetically sealed entry of electrical cables, hydraulic pipelines, and high-pressure air.
One of the "penetrators"
Inspection of the acrylic window mounting location in the forward hemisphere
The acrylic glass porthole (also known as plexiglass or organic glass) was 380 mm in diameter and 180 mm thick and was manufactured by Hydrospace Group Inc. at a cost of $33,450. The porthole was intended to comply with ASME (The American Society of Mechanical Engineers) PVHO-1 (Safety Standard for Pressure Vessels for Human Occupancy) standards. However, at the request of OceanGate management, its shape was modified: the inner surface was made flat instead of spherical "to improve visibility." Since the non-standard glass shape requires extensive testing (up to 10 years) for certification, OceanGate waived this requirement. Therefore, the manufacturer guaranteed its durability only for depths of up to 650 m.
In 2020, Heinz Fritz GmbH manufactured a new glass pane of similar design to replace the one damaged in the fall. Its design pressure limit corresponded to a depth of 4200 meters.
Porthole glass according to ASME PVHO-1 standard (bottom) and actual (top)
Titan's porthole glass
Porthole assembly
"Risk zones" of the pressure hull
Attached to the Titan's robust body was a chassis. It was designed to both mount the apparatus on a horizontal surface and to carry cameras, lighting equipment, scanning systems, and other components that could be jettisoned to reduce weight in an emergency.
Attached to the aft section of the pressure hull was a permeable, conical compartment approximately 1,5 m long, which housed two batteries, a high-pressure air tank, various equipment, including a telemetry system, and buoyancy blocks made of synthetic foam.
Aft compartment (fairing removed)
The ballast system was designed for trimming, diving, and surfacing the vehicle. It consisted of a combination ballast tank and jettisonable weights. An elastic "bag," open at the bottom, was installed in the upper part of the hull, serving as the ballast tank. Together with the high-pressure air system (HPA), it ensured the desired underwater state of positive, neutral, or negative buoyancy. The purge and ventilation valves of the ballast "bag" were controlled by a computer, ensuring the desired level of buoyancy. A supply of HPA, under a pressure of approximately 700 kg/cm², was stored in a 40-liter cylinder.
Sandbag"
Placement of the high-pressure cylinder (indicated by the yellow arrow)
Ballast bag control panel
Before boarding the Titan, all passengers and their equipment were weighed. Based on the combined weight of the crew and the spacecraft, lead weights were added to the landing gear to achieve optimal buoyancy before the dive. Additionally, trim weights were provided in the form of steel pipe sections weighing a total of 180 kg. These could be individually jettisoned using electric drives or an emergency hydraulic drive with a hand pump. In an emergency, the landing gear, along with all attached weights, could be jettisoned to quickly lighten the Titan.
Trimming weights
Control panel for hydraulics for dumping cargo and chassis
For emergency ascent, additional weights were attached to the Titan via a rapidly dissolving anode. The anode dissolved within 24 hours, and the weights were jettisoned.
To maintain the required atmospheric oxygen composition, there was one main and four reserve oxygen tanks (pressure 176 kg/cm²), housed inside the pressure hull and providing up to 96 hours of life support for five crew members. Oxygen supply was manually regulated using a flow meter at a rate of 0,5 liters per minute per person. Electronic oxygen sensors installed inside the apparatus were used to monitor the oxygen content.
CO² levels were continuously monitored by the Titan's control system, and a backup emergency monitoring system was provided in case of control system failure. A scrubber filled with Sofnolime® absorbent was used to remove CO². Air was pumped through it by an electric fan. Emergency CO² removal was accomplished using lithium hydroxide (LiOH) blankets.
A propulsion system consisting of four (two vertical and two horizontal) Innerspace 1002HL Hexscreen Electric Thrusters with 12 hp electric drives served for vertical and horizontal movement. The apparatus' horizontal speed reached three knots.
One of the propulsion units (thruster)
The propulsion motors were powered by two external Ictineu Li-Po® 150V lithium-polymer batteries, rated for full submersibility. One battery powered the vertical motors, and the other the horizontal motors, providing 27 hours of operation.
Ictineu Li-Po® Battery
An internal 24V battery pack powered auxiliary systems. It consisted of four sealed 6V lead-acid batteries.
The electronic equipment consisted of:
- INS/USBL (inertial navigation system/ultrasonic positioning system) from Advanced Navigation
- Teledyne BlueView 2D sonar (90-degree field of view, target detection range up to 300 m)
- Teledyne Doppler Velocity Log
- 2G Robotics Dynamic Underwater Laser Scanner (ULS-500 PRO)
- Outboard photo and video cameras, internal video camera
- Real Time Hull Health Monitoring (RTM) — a system for continuous monitoring of the hull's condition
- Management and control computers
- Four underwater LED lights (40,000 lumens)
There was no underwater voice communication system; communication with the surface could only be maintained via short messages. The maximum text message size was 64 bytes, which typically equates to 64 characters or approximately 10-13 words.
During underwater operations, OceanGate used acoustic telemetry modems from various manufacturers for communications and vessel tracking systems. An ultra-short baseline (USBL) transceiver installed on the submersible support vessel used acoustic signals to determine the range and bearing to tracking targets. The USBL transceiver measured the elapsed time since the transponder received the signal and then converted this time into distance. Using multiple converters, the support vessel's transceiver could calculate the angle to any installed transponder.
One modem was to be installed on the Titan, and a second modem was planned to be placed on the seabed near the Titanic wreck as an acoustic beacon for future dives.
The RTM system was developed and patented by OceanGate executive R.S. Rush and was intended to provide the submersible's pilot with real-time hull monitoring. It consisted of a set of acoustic sensors and strain gauges placed throughout the hull. Signals from the sensors were amplified and converted into digital data. This stream of digitized acoustic emission and hull deformation data was sent to the Titan's main computer for further processing and analysis. Hull condition information was displayed in real time as color-coded bar graphs (green, yellow, and red) for each sensor, indicating whether the readings were within acceptable limits.
The thresholds were set by Rush himself. Green meant the dive could continue normally, yellow meant the dive could be continued with caution, and red meant the dive should be aborted immediately and the diver returned to the surface.
A serious flaw in the system was the fact that the fiberglass insert of the pressure hull blocked access to the sensors. This meant that at the time of the fatal dive, only five of the eight acoustic sensors were operational.
Location of sensors for the Real Time Hull Health Monitoring system
Acoustic sensor and strain gauge of the Real Time Hull Health Monitoring system
Titan's exterior
Inside the Titan
Titan control panel
Titan's control and management system computer
The Titan's control and management computer is bolted directly to the carbon fiber reinforced plastic housing, which reduces its strength.
Information about Titan
Titan was owned by CYCLOPS II LLC (Seattle, Washington, USA), chartered by OceanGate Inc. (Everett, Washington, USA), and operated by OceanGate Expeditions (Providence, Bahamas).
It was discovered that the apparatus had been built and operated "without being registered, certified, inspected or classified by any national or international flag administration or recognised organisation."
According to U.S. Coast Guard policy, certified submersibles—small passenger vessels—are limited to a maximum diving depth of 150 feet (45,7 m), as this is considered the maximum depth to which scuba divers can dive for rescue operations. However, U.S. Coast Guard policy does not set any maximum operating depth limits for special-purpose submersibles.
After numerous interactions with various US Coast Guard units, Rush realized that OceanGate's submersibles did not meet the Coast Guard's strict small passenger vessel certification requirements, prompting OceanGate to reclassify its passengers as "mission specialists," ostensibly performing scientific tasks to conceal its illegal passenger operations. However, Rush never took any steps to certify the Titan. OceanGate's approach to regulatory compliance represented a blatant disregard for oversight by classification societies, state, and federal agencies.
As OceanGate prepared for its maiden expedition to the Titanic site in 2018, the Director of Marine Operations was tasked with inspecting the Cyclops II submersible, later renamed Titan. On January 18, 2018, he submitted a report highlighting critical safety issues. The Director of Operations made clear that the transfer of the submersible from the engineering team to the operations team was the appropriate time to address the safety concerns. In his report, he listed 26 components requiring corrective action or further attention, expressing concern that until these issues were addressed, the submersible should not be used in any upcoming trials. The Director of Marine Operations believed it was important to document these findings and ensure that OceanGate management took them seriously before the submersible was placed into operational service with personnel on board.
Management's response was immediate. On January 23, 2018, OceanGate fired its Director of Marine Operations. The dismissal letter stated: "During a meeting on the afternoon of January 19th, it became clear to [OceanGate CEO/Secretary of the Board of Directors, R.S. Rush] that you and he had reached an impasse regarding the status of Cyclops II and that your dismissal was the only option. Given your qualifications, we are confident that you will soon find another position."
Richard Stockton Rush III (1962–2023) was the CEO of OceanGate and one of its founders. Photo taken in 2015.
In January 2018, Titan's assembly was completed, and its test dives soon began, first in waters off Washington State and then in the Bahamas. These were conducted both unmanned and with a crew. On December 12, 2018, Titan, with R.S. Rush aboard, reached a depth of 3939 meters.
Information