Any side load or binding could allow the thimble to shift its position. As a result of all the stretch, even factory-installed thimbles become loose at high load.Įven when a thimble is very well-fitted and tightly seized-as good and any we have seen-and stretched to the normal working load (10 percent breaking strength), it becomes quite loose. Because each leg of the eye carries only half of the load, the stretch at 20 percent of breaking strength should be only 6 percent, but we must add to that some construction stretch, since it takes time for a splice to settle in. Nylon double braid rope stretches about 12 percent for every 20 percent of breaking strength 3-strand rope stretches about 15 percent and climbing ropes stretch about 18 percent. Cheap wire thimbles often have sharp edges, and even well-polished examples can open the weave or chafe at strands, or seriously damage a splice if they shift.Īt the heart of the problem is stretch. But are thimbles best, and is a thimble best or even required in all circumstances? We are especially interested in strength.Ī light thimble can distort under high load. And the thimble also increases the turning radius, which more evenly distributes the load among the fibers that make up the weave. Undoubtedly, a thick layer of steel provides the ultimate in abrasion resistance when attaching to a rusty, galvanized mooring shackle.

A great many sailors believe a splice intended for high loads is not complete until it is fitted with a thimble.

Splice 2 lines together