Ocean Rigging Discontinuous Rod Rigging is fitted to many Grand Prix Racing Yachts, many of the finest performance Superyachts and large cruising yachts, requiring low maintenance with long use under high load.

All wire ropes and strands stretch under load. The amount of stretch is determined by two components, permanent stretch and elastic stretch.

Permanent stretch is caused by settling of wires in the rope or strand when the initial load is applied. Dyform strand gives very little, if any, permanent stretch as this is removed during the manufacturing process.

Elastic stretch is typical of any metallic material under load and elastic stretch will be proportional to the applied load (Hookes Law). Resistance to stretch is determined by the "modulus of elasticity".

Rather than using Youngs Modulus for the material of the strand, we quote a strand modulus. Load extension data from an actual strand is used together with the nominal diameter of the strand to calculate the cable modulus. This gives a direct comparison between strand types.

Elastic stretch (mm) = (W x L) / (E x A)

where W= Applied Load (KN)
E= Strand Modulus (KN/mm^²)
A= Cross sectional wire area = (D² x p) / 4
D= Nominal Diameter