Matthew Sheahan

A RECENT KEEL FAILURE HIGHLIGHTS WHY MODIFICATIONS CANNOT SAFELY BE MADE WITHOUT BEING PROPERLY VALIDATED

I’ve seen at first hand what a boat looks like when it’s upside down in open water. It’s not nice. I don’t ever want to see it again. It upsets me to hear cases of others who have faced the same terrifying situation. So, when I read the news of the 40ft racer Showtime losing her keel on her return from the Rolex Sydney Hobart Race my heart sank, just as it did when I read about the Hooligan and Cheeki Rafiki tragedies in 2007 and 2014, the Polina Star III sinking in 2015 and the capsize of Tyger of London in 2017.

Losing a keel is as unacceptable as wings coming off an aircraft and yet here we are again with another major failure. Miraculously, in the case of Showtime, all the crew were rescued.

Having studied many keel failures over the years it’s clear to me that this is a complicated area with no magic solution. The modes of failure are as varied as the circumstances that led to them. From keels that fell off new boats through no fault of those on board to failures following serious operator error, the reasons for such catastrophic failure are varied. But the issue of retrofit keels is particularly worrying.

In the racing world it’s understandable why an owner may want to change a keel to improve performance. Rules change, theories alter and designs evolve. It’s easy to jump to assumptions and presume that the kind of modifications that lead to problems involve adding more weight to the keel to increase the righting moment and power of the boat. While in many cases this has been the issue and loads have increased in the structure and at the interface with the hull, Showtime points to a different set of circumstances where the boat’s performance was increased by reducing the weight of the keel.

Showtime was a Ker 40 from 2011, but her modified keel was not produced by the Ker design office.

“We quoted the owner for a replacement keel but later learned that he had gone with a local designer for the project,” explains designer Jason Ker.

“As far as we know the keel was configured as a vertical hollow strut welded to a horizontal mounting plate, which in turn was sitting in a shallow recess in the boat’s hull and bolted to the boat’s structure. This is not a design approach we would ever endorse as the high stress point at the junction is coincident with the horizontal welded joint.”

When people talk of failures in welded keels there’s an understandable tendency to think badly of welds in keel structures, yet it is not the welding that is necessarily the issue. It is more about where and how welds are used that is critical. And even when the design is structurally sound, keels aren’t always built to spec – Tyger of London and Hooligan, being cases in point according to Marine Accident Investigation Branch (MAIB) reports.

Creating rules and regulations to ensure keels are built to design would seem to be a key step in preventing further accidents, yet this is harder than it might seem.

World Sailing’s ‘In Build Validation’ project that looked like it might offer some solutions has been stopped following a rethink. A new Keel Improvements Working Party has been set up to devise and recommend changes to the ISO 12215-9 scantling codes for yachts of under 24m LOA, in order to improve the strength and expected lifetime of keel attachment. The aim is to produce recommendations by October.

Another of the issues that trouble designers such as Jason Ker is that currently it is possible to gain technical approval under various rules but for a design that isn’t necessarily up to the job.

“Our feeling is that providing FEA (Finite Element

Analysis) calculations for any keel designed to first principles, along with supporting structure, is the only safe way to validate a keel design, but that is currently not required for plan approval. Some design offices may resist because it is an expensive exercise to do using costly software and requiring expert knowledge of the process,” he comments.

I’m a pilot as well as a sailor and would feel deeply uncomfortable with modifications to my plane’s wings without some serious evidence from accredited organisations. Why should keels be any different? When keels fall off lives are at risk, surely cutting corners on cost is not an option.

‘Losing a keel is as unacceptable as wings coming off an aircraft’