Heavy Seas and Surf Rescue Techniques – General
In the Hoist Principles post, we introduced the principle features of an effective hoist. In the Hoist Characteristics and the Hoist Spectrum post, we discussed the importance of adjusting your approach depending on where you fall on the hoist spectrum. In this post, we will discuss how to achieve the principles of an effective hoist while performing a hoist in an unbound (obstacle free), dynamic maritime environment (e.g., heavy seas and surf machete hoists). While heavy seas and surf rescues differ in some respects, both require wave anticipation, energy management and a commitment to deployments and recoveries. As outlined in the Hoist Principles post, the overarching goal in both environments is to effectively manage cable tension through deliberate aircraft positioning and hoist control.
Anticipation. A key consideration in both conditions is anticipating how moving water will influence the rescue swimmer (RS) and survivor. In heavy, non-breaking seas, wave energy produces orbital motion—the RS and survivor move up and forward along the face of an approaching wave, crest at the top, then travel down and back into the trough. This circular path returns them roughly to their original position as the wave passes. The distance traveled depends on wave height and length—larger waves result in a wider radius of travel.
In contrast, surf zones are dominated by breaking waves and lateral energy. Unlike orbital movement, surf-induced motion does not bring the RS and survivor back to their starting point. Rather, these forces push them sideways with each wave surge. The degree of lateral displacement depends on several factors: wave size, wave speed, and how abruptly wave energy is released. For example, spilling waves—where only the top slowly crumbles—tend to move individuals a shorter distance than plunging waves, which fold over and crash powerfully into an impact zone. The more sudden and laterally expansive the break (white water), the greater the lateral energy and the larger distance the breaking wave will move them.
Buoyancy and profile in the water also influence how far individuals are moved. RSs wearing wetsuits can often dive beneath the surface energy, minimizing lateral drift. By contrast, individuals in survival suits, anti-exposure garments, or personal flotation devices—especially those floating high—will be more susceptible to displacement.
Anticipating the path of the RS and survivor is crucial for successful hoisting. When deploying the RS, the helicopter crew must anticipate the location where the survivor will be pushed. When deploying the RS near a vessel in the surf, the helicopter crew should position them where they can safely close the distance to the vessel—while avoiding the area where surf conditions could push the vessel over the RS. On recovery, the aircraft positioning and cable control must be based on where the RS and survivor will be after the next wave, not where they are at the moment. This predictive approach enables more effective deployments and recoveries.
Energy Management. The ability to effectively manage wave energy is also critical. When the RS and survivor are attached to the hoist cable, they should remain between the hoist drum and the incoming wave energy. This alignment—wave energy → RS/survivor → hoist drum—creates a manageable scenario where the force of the wave moves the individuals toward the aircraft. The subsequent slack that is produced can be removed by moving the helicopter away and bringing in the hoist cable. When this alignment is reversed—i.e., the helicopter is positioned between the wave and the RS—the force of the wave creates tension on the cable, risking a dangerous shock load on the RS and survivor.
Prior to recovery, crews must manage cable slack and the alignment of energy diligently. When the RS is connected to the hoist hook, there must be enough slack to accommodate wave-driven motion, but not so much that it introduces an entanglement hazard or an excessively long recovery period.
The relationship between wave energy and helicopter heading is another crucial factor in successful hoist operations and will be explored further in future posts. In general, when a swell approaches from the nose of the helicopter, the crew should position the RS and survivor at the 1 to 2 o’clock position to keep them on the hoist (right) side of the helicopter while maintaining proper alignment of energy: wave energy → RS/survivor → hoist drum. If the swell approaches from the tail, positioning the RS and survivor at the 4 to 5 o’clock position preserves the same energy alignment on the hoist side. When a swell approaches directly from the hoist side (right), alignment at 3 o’clock naturally supports effective cable management and energy buffering. The least favorable scenario occurs when the swell approaches from the non-hoist side (left). In this case, maintaining the correct alignment of wave energy becomes significantly more difficult, often requiring the helicopter to hover nearly directly over the RS and survivor—dramatically reducing margin for cable management and increasing the risk of shock loads.
Committing. In dynamic maritime environments, crews must “commit” during both the deployment and recovery phases. On deployment, if the RS intends to disconnect from the hoist hook, the crew must ensure sufficient slack is provided to allow for a clean and timely disconnect between wave sets. During a deployment where the RS remains on the hoist hook, the crew must quickly provide enough slack upon water entry to allow freedom of movement in the waves and position the helicopter to align properly with the energy of the surf (wave energy → RS/survivor → hoist drum).
During recovery the crew must commit to the pickup—managing cable through coordinated hoist control and aircraft movement. One of the most hazardous situations happens when the aircrew hesitates with the RS and survivor in the “exposure zone.” The “exposure zone” is area of transition from helicopter position keeping to RS and survivor recovery when there is insufficient slack for freedom of movement but insufficient tension to fully take the load, making the RS and survivor susceptible to shock loading. In this zone, as a wave lifts the RS and survivor, excess slack accumulates, only to be abruptly removed as they fall into the trough, resulting in a potentially dangerous shock load that can cause injury or damage to the hoist system.
For an effective pick up, the crew must position the helicopter at the edge of the capture radius—the distance within which a safe and timely recovery can occur between waves—and when the timing is appropriate, execute a decisive pickup. This involves a drag to plumb, while simultaneously moving the helicopter laterally in the direction of the RS and survivor, and if necessary, a well-timed vertical climb to expedite the RS and survivor clearing an approaching wave face. When timing is not perfect, it is better to recover the RS and survivor through the face of a wave under tension than to hesitate, or pay out additional cable, that may result in exposure to a shock load.
Review. Successful rescue operations in heavy seas and surf environments depend on anticipation, energy alignment, cable management, and committed execution. Crews must anticipate how wave energy will move the RS and survivor—whether in the circular motion of open-sea swells or the lateral surges of breaking surf—and position the swimmer accordingly. Aircraft and cable positioning should be based not on where the survivor is now, but where they will be after the next wave. Maintaining proper alignment with wave energy—ideally positioning the RS and survivor between the incoming wave and the hoist drum—helps manage slack and avoid dangerous shock loads. Effective cable control and aircraft movement must be coordinated throughout both deployment and recovery. Above all, crews must commit decisively once in position. Hesitation can place the RS and survivor in the exposure zone, increasing the risk of injury or hoist cable damage.
In future posts, we’ll examine wave dynamics and the rescue swimmer deployment and recovery techniques associated with ‘machete hoists’ in heavy seas and surf conditions.
