The length of the thimble required for clamped rope attachments shall be at least how many times the rope diameter?

• A. 14 times the rope diameter
• B. 12 times the rope diameter
• C. 10 times the rope diameter
• D. 6 times the rope diameter

Answer: (A)

A thimble provides a bearing surface for the rope eye, and in a clamped rope attachment you want the rope to bear smoothly along a sizeable length of the thimble. Requiring the thimble length to be at least fourteen times the rope diameter ensures a generous bearing surface and a gentler bend. This distributes load over a larger area, reduces bending stress and edge compression on the rope, and helps the clamp seat securely without causing the rope to deform, slip, or wear quickly. If the thimble were much shorter, the rope would bend more sharply and the clamp would bite more aggressively, increasing wear, risk of slippage, and potential failure. So, fourteen times the rope diameter is the design choice that maximizes safety and longevity of the rope attachment.