A new twist on ropes. (Physics).

The mooring and towing of oil rigs and huge ships rely on the strength and durability of thick ropes and the splices that join those ropes. Yet the mathematical models used to evaluate ropes have long left the splices out of the equations.

Now, Christopher M. Leech of Tension Technology International in Eastbourne, England, has mathematically evaluated three major classes of rope splices. The new analysis, slated for an upcoming Proceedings of the Royal Society of London A, can yield precise predictions about how different types of splices behave, Leech says.

One of the junctions studied is a common braided form called the admiralty splice. Among numerous findings, Leech concludes that friction between strands in an admiralty splice prevents sawlike interstrand motions and holds the splice together. Countering those benefits of the braided geometry, however, the everyday stretching and contracting of the splice rotates strands relative to each other in a scissoring action, creating a splice-damaging type of friction.

To evaluate such factors as friction in old and new splice designs, Leech has added his model of splice behavior into software that previously could predict only the behavior of unspliced rope.--P.W.