Features December 2018 Issue

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?

Brummel lock
Photo courtesy of Marine Accident Investigation Board

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 above) 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 the report published by Great Britain’s 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.

Comments (13)

A cow hitch will slip in Dyneema. In other fibers, it weakens the line about 50%.

Rigging a preventer to the mid-boom, such as a vang, is asking to snap the boom in the event of a knock-down or even extreme heel event when sailing in extreme conditions. The idea of having an adjustable and releaseable preventer is very sound, in fact vital, but it MUST be attached to the end of the boom.

The conventional wisdom, I believe, is that two separate strops, with an eye in each end, is the better way to rig this. The brummel lock was simply a poor construction.

Posted by: Drew Frye | December 10, 2018 4:26 PM    Report this comment

Actually it might have been preferrable to run the preventer from aft of a boom on a starboard tack forward through or around the port bow cleat directly over to the starboard bow cleat and then back aft to tail off on a starboard winch. The preventer should not actually run, so frictionless eyes are not necessary. You just need a preventer line long enough to tie from the end of the boom and run all the way forward then port to starboard then back to a primary winch. All you do is ease over the boom untie the port preventer and retie the starboard line then haul out on your port tack. When not in use the preventer can be left tied off on each end and while remaining rigged through the bow cleats.
I also noticed in the photo that a preventer was rigged to hardware on the boom rather than wrapping a few turns around the boom and securing it with a bowline. Hardware can fail unexpectedly as the case with the strop on the eyes. Wrapping the boom eliminates that failure point.

Posted by: rav555 | December 9, 2018 11:27 AM    Report this comment

I have found that a vang used as a preventer is the best way to go. Positing is infinity adjustable and there is no way a heavy duty vang is going to fail. Too bad I cannot display a picture.

Posted by: ARGONAUTA I | December 9, 2018 10:53 AM    Report this comment

Looking at the "before" picture in the cited report, both the friction ring bury splices look good and the brummel splice was added to keep the friction ring tails even. The brummel eye became loaded in a way that significantly weakened it.

Drew, had the eye been left out and the middle passed through the padeye and cowhitched: 1. That would have been stronger than the brummel, correct? and 2. What are your thoughts on a the tight radius of cowhitching high modulus line - either eyes or loops?

Keith

Posted by: Keith Jones | December 9, 2018 10:07 AM    Report this comment

The clue lies in the flattened clearly fused portion of the broken end of the top piece of the strop in the photo. The Brummel " lock" slipped under extreme load and the line melted due to friction.

Posted by: barnacle bill | December 9, 2018 10:04 AM    Report this comment

With composite booms, preventers MUST be rigged to the boom end to avoid snapping the boom. If the preventer is rigged to the boom end, a rail mounted preventer creates even worse leverage than a bow attachment.

In July 2017 ("The Best Prevention is a Preventer") we discuss the angles and how back-swept spreaders make the problem more difficult. The MAIB reached the same finding.

The forces are huge on these big boats in strong weather and were apparently underestimated. It's easy to think of HMPE as unbreakable, but it's not.

Posted by: Drew Frye | December 8, 2018 4:17 PM    Report this comment

It sounds like his preventer was rigged inproperly.
If the boom was at an acute (small) angle to the line, the forces on the line could have been huge. Why wasn't a preventer rigged to the rail on each side of the boat? If you don't avoid acute angles you can break lines, parts, rip out cleats, etc.
Dave Cole

Posted by: Dave9111 | December 6, 2018 5:28 PM    Report this comment

This article has been updated with a link to the MAIB report, which goes into more details regarding the post accident investigation and the images, which were originally published with the report.

Posted by: sailordn | December 5, 2018 12:09 PM    Report this comment

It was broken at the brummel lock. This strop attached the preventer turning blocks to the bow--the low friction rings you see, one for port and the other for starboard. It was a Y configuration, with the center eye formed with a brummel lock and no bury at all. This isn't clear from the photo, because the eye, at the left side, is blown open. What we are suggesting is that there should have been two separate strops, which what I believe our readers believe and assume they are seeing.

Posted by: Drew Frye | December 4, 2018 4:57 PM    Report this comment

I have to agree with Marcus above- that break appears to be in the middle of the strop not at the splice. Maybe the photo doesn't show it, but it appears to have broken where the line was solid 12-strand dyneema, which does not make sense.

Ray

Posted by: Irunbird | December 4, 2018 4:31 PM    Report this comment

I've sailed large and small, for half-a-century, and have been much impressed by the ingenuity of modern riggers to adopt and adapt, addressing age-old problems using much better modern materials while retaining all the knowhow, craft and respect for 'how the old guys tackled this'. Look, for example, around the website of Colligo Marine. There one can see plenty of examples of the use of strops, blocks, the 'needs of the ship' infused with creative thinking. I've wandered round the maintenance marquees when the AC45s were here in Plymouth, marveling at the ways those riggers had adapted old solutions with hi-tech better mateerials. I've constructed a 'selvagee strop' from 15 rounds of dyneema hollow light line....

Show me a 'Brummel'-held long splice in 3-strand laid Irish hemp!

It takes only an inquiring mind and the willingness to think out of the box....

Posted by: oldbilbo | December 4, 2018 1:57 PM    Report this comment

Is the picture of the actual broken preventer? That one is not broken at the brummel lock.

Posted by: Marcus Ward | December 4, 2018 12:06 PM    Report this comment

Centuries of experience with splicing 3 braid ropes and using conventional tried and proven knots has long kept blue water sailors from Davy Jones locker. But my devoted race oriented sailmates with their new hi-tech exotic lines seem to be replacing their lines on an annual basis to the delight of the ship chandlers. Maybe having the "best and latest" hi-tech lines isn't going in the right direction. In the old sailing days every Jack could depend that his shipmates knew how to "do their lines and splices". Their lives dependended on "lines and splices done right". Maybe we've lost sight of the obvious rules of safety here.

Peter I Berman
Norwalk, CT

Posted by: Piberman | December 4, 2018 11:53 AM    Report this comment

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