Titan Submersible Hearings Highlight Several Problems With Its Carbon Fiber Hull

The crash of The TitanThe new carbon fiber hull was found to be split into three separate layers, US National Transportation Safety Board engineer Donald Kramer told the Coast Guard in the case of the OceanGate submersible’s death in 2023.

Although Kramer did not offer an opinion on what caused the boat to break into different layers, he testified to many problems with the ship, starting with its construction in 2020.

Using samples of carbon fiber preserved from its construction, as well as dozens of pieces found on the ocean floor, the NTSB has provided the most complete picture yet of the test’s condition. The Titana bag.

After the The TitanOceanGate’s original structure was found to have cracks and fissures following a deep dive in 2019, and OceanGate commissioned manufacturers to replace it.

A new manufacturer, Electroimpact, used a multi-stage process to investigate and cure a five-inch-thick coating in five different layers. Each layer would be baked at high heat and pressure before being laid down, with a sheet of glue, and another layer built on top. The idea behind this multi-step process was to reduce wrinkles in the final skin that the company believed caused test models to fail deep in their design.

However, Kramer testified that the NTSB found several anomalies in the new skin samples. There was loosening in four of the five layers, with wrinkles that got worse from layer to layer. The NTSB also found that some layers had porosity—the voids in the resin material—four times that specified in the design. It also recorded the voids between the five layers.

On Monday, Roy Thomas, a materials expert from the American Bureau of Shipping, told the case: “Defects such as voids, surface bubbles, and porosity can weaken the carbon fiber, and under high hydrostatic pressure can accelerate the failure of the boat . “

OceanGate did not make any additional test models using the new multi-stage process.

The NTSB was able to recover several pieces of the carbon fiber hull from the ocean floor, one of which was still attached to one of the titanium end domes. In a report released concurrently with Kramer’s testimony, the NTSB noted that there were few, if any, thick slices. All the visible pieces had been split into three shells: an inner one with five layers, a shell made of the second and third layers, and another with the fourth and fifth layers. Like a peeled onion, the hull was largely divided into layers of adhesive.