Splice Failure Linked to Fatality


You don’t have to look far to find a case in point supporting our recent Practical Sailor Special Report on high-tech lines, which emphasized the importance of paying attention to detail when working with ropes made of ultra-high molecular weight polyethylene (UMWPE) fiber.

On September 4, 2015, Andrew Ashman was killed during an accidental jibe, when the boom delivered a fatal injury to the base of his neck. The boat, CV21 Ichor Coal, had been running in strong conditions, and yawing allowed the wind to get on the wrong side of the mainsail, as occasionally happens. A preventer was rigged, but a strop securing a low friction ring turning block near the bow failed, allowing the boom to cross the cockpit unrestrained. On such highly engineered boats, how did this happen?

According to the report published by Great Britains Marine Accident Investigation Board, the failure was traced to a poor choice of splice. Also sometimes referred to as High Modulous Polyetheylene (HMPE) ropes, UHMWPE products like the Marlow D2 Racing Rope used on the Clipper boat or a similar products (Samson’s Amsteel, NE Ropes’ Endura), must be spliced using product specific procedures. All common sailing knots will slip at a small percentage of breaking strength unless modified, and even then, the low stretch nature of HMPE makes them low strength (poor load sharing).

The standard method for forming eyes in hollow braid ropes, like that in question, is a long bury splice, where the tail is about 72 line diameters long. Like a paper finger trap, the harder the rope pulls, the more the herring bone weave contracts on the buried tail.

To prevent the long bury splice from loosening as the rope flops around unloaded, the tail is locked in place at the base of the eye with either lock stitching or a Brummel lock. Neither adds much strength to the splice, and both are intended only to stabilize the splice when unloaded, something all splices can benefit from.

Because there was not enough space for a long bury on each tail, the rigger apparently relied on the Brummel lock alone to carry the load.

This decision was based on the misconception that a Brummel lock actually locks the lines together and can carry safely load. In actual fact, a single Brummel (two passes), such as used on Ichor Coal, can hold only 40-60 percent of breaking strength before failing, which it did.

A better construction, when space is limited, is two separate spliced loops, as used on manufactured products such as Harken LOOPS or pre-spliced low friction rings from Antal, Nautos, and others.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at darrellnicholson.com.