Most of USVs are equipped with an unwinding system stored on a winch to drag several hundred meters of umbilical cable with a large diameter of around 15 mm. It requires a significant energy source to power the system. It also implies the addition of a costly rotating joint (revolving joint/rotary seal/slip ring). Besides, the drag of the umbilical cable in strong currents has a high impact on the hydrodynamic behavior of the ROV. This “traditional” solution results in a cumbersome, heavy, costly, and inefficient cable.

To overcome these problems, SEDI-ATI has designed a range of disposable and lightweight fiber optic spools for tethered vehicles. The spool also called “tape”, is directly mounted onto the ROV. Hence, it is the ROV that deploys the optical cable, and no more the USV. Therefore, there is no traction nor any other mechanical force applied to the optical fiber. As a result, we can propose fiber optic spools at lower costs, in smallest versions, and more efficient in depths and in currents than “traditional” umbilical cables.

SEDI-ATI fiber optic spools for tethered vehicles are composed of a very compact and light package in which is included a precision wound untwisted 250 µm optical fiber allowing long-distance deployment up to 20 km. The fiber can be reinforced with a 350 µm coating for optimum resistance allowing higher speed payout. The deployable side of the spool is equipped with a connector to be connected to the control station on the USV, and the opposite fiber end is pigtailed with a 1.8 mm standard jacket to be connected to an hermetic feedthrough on the ROV. And of course, we can design tapes with different optical fiber lengths, depending on the mission.

Another significant advantage of our solution is that the optical cable can be dumped into the sea, allowing to shorten the minefield clearance missions since there is no more need to rewind the cable.