Land, Sea, or Helicopter-Assisted Sea Cave Rescue
When survivors cannot exit a sea cave under their own power, rescuers must establish a reliable way to enter and exit the cave safely.
As discussed in the previous posts (Sea Cave Rescue and Sea Cave Considerations), sea caves can produce powerful surge, strong currents, and violent rebound energy. If conditions require a rescue swimmer to enter a cave in dynamic conditions, the swimmer should always retain the ability to either pull themselves out or be pulled out using a line.
Ideally, two rescuers are involved. One remains outside the cave while the other enters, tending a lifeline for the swimmer inside.
The trail line carried by our helicopters is orange polypropylene. It works well because it floats—reducing entanglement hazards—and its bright color improves visibility inside a dark cave. However, it is only 105’ long. Multiple trail lines will have to be combined.
If two rescuers are not available, a single-rescuer option is to place climbing protection such as cams or nuts into cracks in the exterior rock to create an anchor point for the lifeline. Because cams and nuts rely on tension to remain secure, they must be placed above the waterline when using floating line. Slack created by wave motion can allow the protection to twist or rotate and potentially come free.
Other objects outside the cave may also serve as anchors. Boats or personal watercraft generally cannot—and should not—enter a sea cave, but they may be able to anchor a line outside the entrance. Care must be taken to avoid fouling the propeller or jet intake.
As a last resort, the helicopter can assist with the rescue.
Testing has shown that a swimmer should not enter a sea cave while attached directly to the hoist cable with an appreciable catenary. The cable is heavy and sinks, creating the risk of it wrapping around submerged obstacles on the cave floor. This can foul or part the cable. In a worst-case scenario, the cable could run beneath an obstruction and pull the swimmer underwater against it. With tension on the hook, the swimmer may not be able to disconnect.
Even without fouling, the weight and drag of the cable can make swimming nearly impossible if enough cable is payed out.
Since the hoist cable is not suitable as a cave lifeline, the swimmer should instead be lowered to the water while holding the trail lines. Once in the water, the swimmer disconnects from the hook, sends one end of the trail line back up to the helicopter via the hoist hook, and secures the other end to themselves. The flight mechanic then tends the trail line by hand.
During extraction, tending the trail line by hand allows the flight mechanic to feel the load directly. This enables the helicopter to move slowly and deliberately while the flight mechanic dampens sudden jerks in the line.
Maintaining roughly a 45-degree angle on the trail line helps prevent the swimmer from submarining during the tow and helps keep both the swimmer’s and survivor’s heads above water. Slow and steady wins the day.