For more than 35 years, Practical Sailor has been taking the guesswork out of boat and gear buying with bold, independent boat tests, and product-test reports for serious sailors and boaters. In this report, they remind us of the risks from poor rigging.
On 4 of September 2015, Andrew Ashman was killed during an accidental jibe, when the boom delivered a fatal injury to the base of his neck during the 2015-16 Clipper Round the World Race. 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?
Instead of using two independent strops to handle the load off the preventer, the rigger on Ichor Coal used single long strop with low friction rings eye-spliced at each end. A Brummel lock (see image) was added to keep the strop in place on the bow fitting where the strop was secured.
This type of Brummel can only hold about 40-60 percent of the breaking strength of the line. In addition, the preventer was led at a very acute angle to the boom (see PS June 2017, “The Best Prevention is a Preventer”)
According to Great Britain’s Marine Accident Investigation Board, the failure was traced to a poor choice of splice. High Modulous Polyetheylene (HMPE) ropes, like the Marlow D2 Racing Rope used on the Clipper boat or Amsteel, 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.
Read the full story at Scuttlebutt: https://www.sailingscuttlebutt.com/