Röhlok — Modular oil-filled subsea cables for ROVs, Australia

Every work-class ROV runs on a loom of electrical cables — to cameras, lights, sensors, manipulators, tooling. Traditionally those are moulded rubber units: when one fails offshore, it cannot be repaired, a spare has to be on board, and the spares list grows with every piece of third-party equipment the vehicle might carry. Röhlok replaces them with a modular, oil-filled subsea cable system that can be repaired and reconfigured in the field.

The company's claim is specific: independent testing commissioned by a number of ROV companies has confirmed that oil-filled cables have an expected life at least three times that of a moulded rubber unit. Röhlok attributes this partly to the conductors being free to move within the outer sheath, which reduces stress and the chance of an open circuit.

Construction is 316 stainless steel, non-plasticised polyurethane tubing and MILSPEC-grade TFE-coated conductors. Röhlok makes a point of the tubing: it is custom-extruded without plasticisers, so, unlike another well-known brand commonly used offshore, it stays flexible after exposure to UV light and hydrocarbons rather than going brittle and cracking.

The cables are independently hydrostatically tested and certified to 5,000 psi (3,424 MSW), and designed to exceed the requirements of most modern work-class ROVs and ancillary equipment. The company also addresses the traditional objection to oil-filled cables — that making and repairing them is fiddly and messy — by stating that every part of the assembly and filling process has been redesigned to be clean and efficient.

Dual-end oil-filled cable — the direct replacement for a traditional moulded rubber cable. Standard lengths 9′ (3 m), 12′ (4 m) and 15′ (5 m), or any custom length. Fitted as standard with genuine Burton™ 55 series connectors. Described as excelling in demanding applications such as cameras on pan-and-tilt actuators.

Single-end oil-filled cable — developed at customer request to adapt traditional moulded rubber tails to the oil-filled system. Lengths 3′ (1 m), 6′ (2 m), 9′ (3 m) or custom. Fitted with a genuine Burton™ 55 series connector and a Pflitsch blueglobe® gland. Röhlok positions this as a permanent way to connect proprietary cables or use up existing stocks of cable tails rather than a temporary workaround.

Multi-end oil-filled cable — for inspection tools carrying both a camera and a light, twin lights on a single circuit, or third-party equipment with multiple sensors. One end carries a Burton™ 55 series connector for the ROV; the other ends can take barbs for oil-filled tubes, Pflitsch blueglobe® glands for moulded whips, or a mixture. Presented as a replacement for leaky potted joints in Y-spliced moulded cables.

Seanet and custom variants — all variants are now available with Schilling Seanet connectors for integration with Schilling vehicles and equipment. The system also supports SubConn® Circular / Micro Circular and SEACON MINI-CON connector types. Multi-way connections use precision-milled 316 stainless steel splitters and connector adapters.

One detail worth noting for toolers: despite the slimline central housing, Röhlok can build active electronics into the cable itself. The example given is a camera cable with a tri-state to bi-polar module that gives full zoom and focus control without modifying either the camera or the ROV.

Tristan Janle spent eight years operating ROVs with DOF Subsea, TechnipFMC and Helix Energy Solutions (Canyon) before concluding there had to be a better answer to ROV connectivity failures. He designed, tested and manufactured the Röhlok system, which the company states has been supplied to and used in service by two of the world's top ROV contractors. He also completed RMIT University's LaunchHub #14 programme for startups addressing the UN Sustainable Development Goals, winning the pitch competition at its conclusion.