A cleverly modified Saab Seaeye Falcon ROV is helping the Los Angeles Long Beach Fire Department to turn more recovery missions into live rescues.
Finding a victim under water within the ‘Golden Hour’ determines whether a mission is a rescue or a recovery, but the modified ROV aims to cut the search time from an average of three hours, down to less than 30 minutes.
“We wanted something that was not too expensive,” explained Stan Jackson of the Long Beach Fire Department, but could handle the technology, and work in confined spaces and out in the ocean. And also something we could get going quickly.”
Pinpointing a victim on the seabed in dark and murky waters, with only a vague idea of where they entered the water, has long been a frustrating and time-consuming operation.
Current practice is to lower tripod-mounted sonar from a boat to the seabed at repeated intervals to scan the immediate vicinity – as soft tissue can only be detected at short range by very high-resolution sonar.
This grid search from what is called the ‘point last seen’ can take up to three hours, with divers sent down at intervals to investigate any soundings.
But finding a faster solution using ROV-mounted sonar seemed impossible, as the kind of high-resolution sonar system able to detect soft tissue is too large and heavy to be mounted on an ROV small enough to be manhandled into the water for rapid deployment.
The benefits that an ROV has over a diver is that it doesn’t need to see in the dark or take breaks because it can recover a victim with its manipulator, but it needed to be modified in order to be used for SAR missions.
The team were faced with the problem of trying to fit a metre-long sonar device onto a metre long ROV, which they solved by splitting the sonar unit in two. The sonar head was fitted to the rear of the Falcon, with the electronics pack squeezed inside.
But they also had to solve the weight issue because this type of sonar would normally sink or destabilise a small ROV.
Saab Seaeye engineers discovered a way to manage the buoyancy of the ROV and balance it to stay afloat and remain stable for accurate sonar scanning. The Falcon’s five powerful thrusters meanwhile handle the weight and manoeuvrability, whilst working in currents and deep water.
The Falcon is one of most successful ROVs in the range from Saab Seaeye, the world’s largest electric ROV manufacturer. It can also be used to inspect the hulls of ships in the harbour, and check bridges after an earthquake.
Saab Seaeye will be exhibiting at this year’s Seawork International on stand number B95.