My personal view on the Bayesian Investigation, MAIB Interim Report and what the industry can do now to improve safety ( by Andy King )

Director for Stability & Statutory at Houlder Ltd; Chartered Naval Architect and specialising in vessel stability

With my experience and background, I have been closely following the Bayesian investigation and available information since the tragedy occurred.

I preface my comments below by saying that I am an experienced Naval Architect with expertise in yacht stability, stability information booklets and stability problem-solving. 

I have been responsible for many yacht stability approvals and led on yacht stability criteria development. I am not a seagoing individual or weather expert.

I have received several questions on the incident, both publicly and privately, but we now have the interim report from the Marine Accident Investigation Branch (MAIB) 

detailing their investigation thus far. This report is extremely helpful in getting the narrative and technical details into the public domain. It does so from a very considered and analytical perspective.

The interim report describes the situation and actions of the crew onboard, in what must have been awful circumstances and an extremely rapid knockdown. 

Putting the tragic loss of life, legal ramifications, and media interest to one side, the technical investigation is still ongoing by the MAIB and there will still be much to learn. 

There is the wreck to raise, further aspects to consider and plenty of work to be done.

The thorough technical work in the report has identified the likely stability characteristics of the yacht at the time of the incident, the likely angle of vanishing 

stability and the likely wind-speed required to cause a knockdown. This has correlated well with other publicly available industry studies, and this tends towards good confidence in these numbers.

As I discussed in a recent industry technical presentation, the sailing yacht stability criteria do not take windage into account – the criteria are purely dependent on the

righting lever curve, which is itself dependent on the buoyant hull and the downflooding angle of the yacht. The downflooding angle is just as important as the angle of vanishing stability.

For anyone who wishes to read the historical origins of the sailing yacht criteria, please read the 1990 paper ‘The Development of Stability Standards for UK Sailing 

Vessels’ where it discusses the types of stability casualty. In this paper, it describes wind-induced capsize and wind-induced downflooding.

The final report and final recommendations could be more than a year away. So, what can be done now? As a call to action for the industry and to improve overall safety levels, 

it is possible to be proactive and investigate the stability of your yacht. Questions to be asking are:

1. When was your lightweight last assessed? When did your yacht last have a lightweight survey or incline experiment?
2. What is in your Stability Information Booklet? And crucially, does it reflect how the yacht is operating?
3. Do the approved loading conditions reflect how the yacht is really loaded?
4. Digging deeper, how does my yacht respond to extreme weather?

The answer to question 4 will not be in your stability information booklet. It is possible to engage a Naval Architect and use modern CFD techniques to find out how the yacht 

will behave in wind and wave conditions. The output from this study can be distilled into operational information which can be placed onboard and be used for decision making.

I look forward to reading the final report from the MAIB and observing the industry direction which will follow. The possible recommendations may cover yacht design, loading conditions, 

sailing yacht stability assessments and the information contained within a stability information booklet - and how that stability information booklet is used onboard. 

I look forward to being able to contribute, where I can, to the industry discussions as and when they occur.

My overall personal aim is to improve yacht safety and to ensure that the critical aspect of yacht stability is central to their design and operation.