The Titan Submersible’s Carbon Fiber Hull Under Scrutiny in Hearings
The investigation into the fatal implosion of the OceanGate submersible, the Titan, has revealed troubling findings regarding its innovative carbon fiber hull. During a Coast Guard hearing, US National Transportation Safety Board engineer Donald Kramer disclosed that the wreckage of the Titan’s carbon fiber hull was discovered separated into three distinct layers. While Kramer refrained from speculating on the exact cause of the hull delamination, he highlighted multiple issues with the hull dating back to its manufacture in 2020.
Manufacturing Problems and Experimental Nature of the Titan’s Hull
Samples of carbon fiber from the Titan’s construction, as well as numerous pieces recovered from the seabed, provided the NTSB with a comprehensive understanding of the experimental nature of the Titan’s hull. Following the discovery of a crack and delamination in the first hull after deep dives in 2019, OceanGate enlisted a new manufacturer, Electroimpact, to replace it. Electroimpact utilized a multistage process to wind and cure the five-inch-thick hull in five separate layers.
The multistep process involved baking each layer at high temperature and pressure, grinding it flat, adding an adhesive sheet, and applying the next layer on top. This approach aimed to reduce wrinkles in the final hull that had previously led to failures in test models. However, Kramer’s testimony revealed several anomalies in the fresh hull samples, including waviness in four of the five layers, increasing wrinkles from layer to layer, and porosity exceeding design specifications. Additionally, voids were found between the five layers, raising concerns about the hull’s structural integrity.
Expert Testimony and Concerns About Hull Defects
Materials expert Roy Thomas from the American Bureau of Shipping emphasized that defects such as voids, blisters on the surface, and porosity could weaken carbon fiber and accelerate hull failure under extreme hydrostatic pressure. The NTSB’s investigation indicated that the Titan’s carbon fiber hull had largely separated into three shells: the innermost layer, a shell comprising the second and third layers, and another consisting of the fourth and fifth layers. This separation was attributed to delamination at the adhesive joining the layers.
Acoustic Sensors and Strain Data Analysis
Phil Brooks, OceanGate’s former director of engineering, testified about a loud bang heard when the Titan resurfaced from a dive to the Titanic in July 2022. Acoustic sensors on the carbon fiber hull captured the noise, while strain gauges indicated a shift coinciding with the bang. Brooks acknowledged that three strain gauges on the Titan had never functioned properly since its rebuild, and he deferred mechanical assessments to CEO Stockton Rush, who tragically perished in the Titan.
Despite the concerns raised by the acoustic sensors and strain data, Brooks and Rush continued the Titanic dives without further investigation. The NTSB’s analysis revealed persistent changes in strain data over subsequent dives, indicating ongoing issues with the hull. Brooks expressed frustration at being unable to bring the Titan back for testing due to cost constraints, leaving the submersible docked in Newfoundland without repairs or adjustments for several months.
Continued Investigations and Future Expectations
The Coast Guard hearings are ongoing, with a final report on the Titan’s accident expected in the coming months. The scrutiny over the carbon fiber hull of the Titan has raised significant questions about its structural integrity and the decision-making processes that led to the fatal implosion. As the investigation delves deeper into the root causes of the hull failure, the maritime industry awaits critical insights and recommendations to prevent similar incidents in the future.
