Examining the Odysseus 6K: the ROV that found the Titan sub

Yes, so grand is the transformational change, that underwater Remotely Operated Vehicles (ROVs) have now been used in high profile and highly delicate situations: like searching for the ill-fated Titan submersible.

In case you have forgot, the Titan submersible, operated by American tourism and expeditions company OceanGate, went missing in the middle of June with five passengers – including the company’s CEO - on board whilst on an expedition to view the wreck of the Titanic in the North Atlantic Ocean near Canada. A desperate search begun following the loss of contact between the vessel and HQ, but after four days, debris was discovered, and news soon followed that the vessel imploded with all lives lost. 

The Odysseus 6K ROV from Massachusetts-based Pelagic Research Services, was identified as the ‘primary asset’ used in the search and potential rescue. It was even the vehicle that made the grim discovery that the submersible had come apart after it uncovered debris near the ship's wreckage, about 13,000 feet beneath the surface in the North Atlantic. Yet, crew were prepped to carry out not just reconnaissance, but a rescue. If rescuers discover that the Titan sub was intact but trapped near the seafloor, an ROV would be the likely asset to effect a retrieval, as plans were drawn up to integrate a lifting line with Odysseus 6K's own capabilities. Should the issue be that the Titan had somehow become stuck, the Odysseus’s two claws could have been deployed to help the sub remove the weight and allow the titan to use its natural buoyancy to float back to the surface.

This plan highlights the range of capabilities that ROVs’ now possess. ROVs can be compared to the drones of the sea. They are able to operate at depths through cables being connected, usually to a control room onboard a nearby vessel, and to the submerged vehicle. This cable transmits power and control signals to the vehicle to allow operation, lighting and can even allow the use of a live video feed so the controller can effectively navigate. Equally, if visibility is limited, ROVs can guide to locations of interest by sonar from surface vessels and buoys dropped from the sky.

The Odysseus 6K, a  ~1700kg vehicle,was launched and recovered using an A-frame crane and is connected to theHQ, a six meter container, through 7,500m of umbilical cable. It has seven hydraulic thrusters, with four horizontal and three vertical; its maximum power output is 19kW, measured at the shaft and has a payload tray that measures 473⁄4 in (1,210 mm) W × 32 in (810 mm) L × 15 in (380 mm) H. The tray can be extended using the onboard hydraulic system and is intended for retrieving samples or carrying sensors and/or equipment. It can survey the ground via video and still image transects.

Previously ROVs have been used for various purposes, such as oil and gas exploration, oceanography; marine archaeology, and environmental monitoring, and although have been used by some police forces to search for persons suspected to have drowned, the case of the Titan is one of the most high-profile uses of them trying to track down a submersible with people still alive on-board.

An ROV was believed to be used in this search and rescue attempt because they generally can operate at much deeper depths than manned vessels, and the fact that without a crew, means it is safer to do so. Yet such was the scale of the feat, that Pelagic even lost one ROV after attempting to send it deeper to the seafloor, highlighting that despite ROVs apparent advantages over traditional manned submersibles, little technology is currently available that can match the crushing pressure of the sea.