Nylon roping exposed to moisture loses roughly what percentage of its strength?

• A. 15%
• B. 5%
• C. 30%
• D. 50%

Answer: (A)

Nylon rope is hygroscopic, so when it absorbs moisture the polymer chains soften and intermolecular forces are reduced. This plasticizing effect lowers the rope’s tensile strength when wet. In typical rescue-grade nylon rope, the strength loss from moisture is about 15%. That means a dry-rated rope will have roughly 85% of its dry strength once wet. The other percentages don’t align with standard data for nylon under common wet conditions; 5% is too small and 30% or 50% would be unusually large except in extreme cases. In practice, this modest but real drop is why wet strength is considered in planning loads and selecting rope for potentially damp environments.