Controlled Buoyant Lift


Controlled buoyant lift (CBL) is a critical rescue technique employed by scuba divers to safely and efficiently bring an incapacitated diver to the surface from depth. This maneuver requires the rescuer to be proficient in buoyancy control, underwater communication, and emergency response. Timely execution of CBL can prevent serious injury or fatality in diving emergencies, emphasizing the importance of proper training and practice for all divers.


Scuba diving, while a popular recreational activity, entails inherent risks. In the event of a diver experiencing difficulty, it is crucial for their fellow divers to be equipped with the skills necessary to respond effectively. The controlled buoyant lift is a standard component of diver rescue training, with its origins dating back to the early days of scuba diving. Over time, the technique has evolved and been refined to increase efficiency and safety.

Principles of Buoyancy

Understanding buoyancy is fundamental to executing a controlled buoyant lift. Buoyancy is the upward force exerted on an object submerged in a fluid, opposing the force of gravity. In scuba diving, buoyancy is influenced by factors such as the diver’s weight, wetsuit, and the amount of air in their buoyancy control device (BCD).

To perform a controlled buoyant lift, the rescuer must manage the incapacitated diver’s buoyancy while simultaneously maintaining their own. This involves adjusting the air in both divers’ BCDs to achieve a slow and controlled ascent to the surface.

Preparing for a Controlled Buoyant Lift

  1. Assess the situation: Upon identifying an incapacitated diver, the rescuer should first evaluate the environment for potential hazards and ensure their own safety. They must also signal for help from other divers or surface support if available.
  2. Approach the diver: The rescuer should approach the incapacitated diver cautiously, maintaining eye contact and monitoring their condition. If the diver is responsive, the rescuer should attempt to communicate their intentions.
  3. Secure the diver: The rescuer must firmly grasp the diver’s BCD, harness, or tank to establish a secure grip. This ensures the incapacitated diver will not slip away during the ascent.

Executing the Controlled Buoyant Lift

  1. Inflate the BCDs: The rescuer should carefully add air to both their own and the incapacitated diver’s BCDs. The goal is to achieve positive buoyancy, allowing for a slow and controlled ascent. Over-inflation should be avoided, as it can result in a rapid, uncontrolled ascent, increasing the risk of decompression sickness.
  2. Ascent: During the ascent, the rescuer must maintain a secure grip on the incapacitated diver and monitor their own buoyancy. They should also frequently check the depth gauge to ensure a safe ascent rate, ideally not exceeding 18 meters (60 feet) per minute.
  3. Vent air from BCDs: As the divers ascend, the air in their BCDs will expand due to decreasing pressure. The rescuer must release air from both BCDs to maintain a controlled ascent rate and avoid over-inflation.
  4. Surface support: Upon reaching the surface, the rescuer should immediately establish positive buoyancy for both divers and signal for assistance from surface support or other divers. The incapacitated diver’s airway should be kept clear, and they should be monitored for signs of injury or illness.

Training and Practice

As with all scuba diving skills, controlled buoyant lifts require regular practice to maintain proficiency. Rescue diver courses offered by various scuba certification agencies, such as PADI, NAUI, and SSI, include training in controlled buoyant lifts and other essential rescue techniques.


The controlled buoyant lift is a vital rescue technique for sc

uba divers, enabling them to safely and efficiently bring an incapacitated diver to the surface. Mastery of buoyancy principles, clear underwater communication, and swift decision-making are key components of a successful CBL. The importance of proper training and regular practice cannot be overstated, as the ability to execute this technique can be the difference between life and death in a diving emergency.

Additionally, divers should always adhere to safe diving practices and maintain awareness of their own limits and those of their dive buddies. By cultivating a safety-conscious mindset, the risk of diving incidents can be minimized, reducing the need for emergency rescue techniques like the controlled buoyant lift.

Advanced Applications

Controlled buoyant lifts can be adapted and applied to various diving situations. For example, public safety divers, such as police and fire department dive teams, may utilize CBL techniques in underwater body recovery operations. In these instances, the technique may be modified to accommodate the use of specialized lifting equipment, such as lift bags or surface-supplied air systems.

Similarly, technical divers who engage in deep, decompression, or wreck diving may also benefit from proficiency in controlled buoyant lifts. The ability to safely and efficiently raise an incapacitated diver in these challenging environments can be crucial in preventing serious injury or loss of life.

Equipment Considerations

When performing a controlled buoyant lift, divers should ensure that their equipment is in good working order and configured for easy access. For instance, the rescuer’s inflator hose should be readily available to inflate both BCDs. Additionally, cutting tools, such as dive knives or shears, should be carried in case entanglement becomes an issue during the ascent.

Prevention and Education

The ultimate goal of diver rescue training is to prevent incidents from occurring in the first place. Education plays a vital role in promoting safe diving practices and equipping divers with the knowledge and skills necessary to respond effectively in emergency situations. This includes understanding the causes of diving incidents, such as equipment malfunction, diver error, or environmental factors, and taking proactive measures to mitigate these risks.

Dive centers, instructors, and certification agencies should emphasize the importance of rescue training and encourage divers to regularly update their skills. By fostering a culture of safety and preparedness within the diving community, the need for controlled buoyant lifts and other rescue techniques can be minimized, ensuring that scuba diving remains an enjoyable and rewarding pursuit for all.