How much strength is reduced when lines are used on double bitts with figure eights?

When lines are used on double bitts with figure eights, the strength reduction is typically quantified as 25 percent. This means that the effective working load of the line is reduced because of the way the line wraps and distributes force over the bitts. The figure eight is a common method to secure a line, but it introduces bends and friction that ultimately reduce the line's capacity to handle loads safely.

This scenario primarily accounts for the mechanical advantages and disadvantages inherent in how the line interacts with the bitts, including the risks of potential slipping or chafing. It's essential for sailors to understand these reductions in strength to ensure that they are rigging lines safely and effectively, maintaining the integrity of their mooring or towing setups. Proper knowledge of these reductions helps prevent equipment failure, which is vital for the safety of both personnel and the vessel.