What is a major disadvantage of using a Single Mainline Separate Belay (SMSB) system?

A major disadvantage of using a Single Mainline Separate Belay (SMSB) system is the challenge of maintaining a smooth edge transition. This system involves the use of a single main rope for the climber or subject and a separate belay system, which can become complicated as the edge of the cliff or rescue site might create friction and drag on the lines. When transitioning from one area to another, such as from moving onto a horizontal surface, any snagging or dragging can lead to difficulties in maintaining control and safety as the system is manipulated.

The smooth transition is crucial for the safety of the rescuer and the victim, as any jerky movements or sudden shifts in weight can compromise the stability of the belay. Thus, ensuring a smooth edge transition is essential for effective operation, and the complication introduced by the design of the SMSB system can hinder this crucial aspect.