Supporter Arne, who singlehands a lot, and whose thoughts informed a lot of my recent Tip on singlehanding, got me thinking again with his latest comments mentioning and linking to The Swiss Cheese Model.
I had not heard of this model before, but it’s a great way to think about mitigating the risks of offshore sailing.
I think it’s a particularly smart way to think because it gets us away from fixating on which piece of gear is best, to a holistic view of how the right gear and techniques add up to seamanlike voyaging.
Active And Latent Failures
I also found the explanation of how the combination of active and latent failures add up to an accident useful.
Real World Application
The recent loss of Solution is an example of this all-too-common phenomenon:
Hello John
Considering our specific environment I do not agree that the swiss cheese model is practical useful regarding risk assessment. It is more useful in understanding and analyzing unintended events or accidents, and thereby making future improvements to procedures and plans. It explains the different layers in place to protect a given event or procedure.
For our purpose the use of risk assessment should be a continuous focus on present and future risks and threats. In my opinion it is good seamanship to continuously evaluate potential risk and threats and plan and brief for possible mitigation. Have a plan B and C if things goes south. It is a dynamic process looking ahead.
The swiss cheese model is more about making the mission (your voyage) resilient to unintended and unforeseen events. Ie, we have chaff protection on sheets and halyard , if it fails we have an extra rope, or maybe even 2. We understand the chaff threat, so on long distance cruising every morning we walk the deck to inspect known risk areas as to mitigate potential failures – that is risk management.
“Risk is a function of the values of threat, consequence, and vulnerability. The objective of risk management is to create a level of protection that mitigates vulnerabilities to threats and the potential consequences, thereby reducing risk to an acceptable level.
Risk is a very broad term. Fatigue is a risk. An example on how we also could include fatigue in risk management : Its has been a very tough day sailing and the night won’t be much better entering difficult waters. We are all tired, so at sunset we take an extra reef in the main to slow down and change the watch schedule from 4 to 2 hour watch, and the obligation to call the next on duty if having problems with staying awake or for any reason feeling uncomfortable of the situation.
So to recap: Threat is something unwanted coming at you. Risk the potential consequences made obvious by risk assessment. Risk management is how we mitigate.
And may I as an x-airline pilot recommend : Make and use checklist. When things heat up we need well thought out procedures and structures to help us thru. If caught unprepared when things go south, half the brain often goes down the drain.
Best regards
Klaus
Hi Klaus,
Each to their own, but I still really like the Swiss Cheese Model, particularly as a way to think about what gear and procedures to layer, albeit with the caveat I ended with, that more is not necessarily better. That said, I certainly agree that there are other parts of risk management, for example, as you say, the balancing of frequency and consequence which I write about here (#7): https://www.morganscloud.com/2024/12/17/8-offshore-cruising-boat-gear-evaluation-tips/
I also like check lists and thinking through possible problems before they happen.
We have been using this threat/error entrapment model in aviation for years. Simple recognition of what is going on and then changing one simple variable can have huge safety benefits. We have applied this to our boat and always brief/have a plan for an anchorage, marina or anything like that. That we be know what to expect from each other and that allows us to recognize that something is not as expected.
a dumb question maybe, sorry.. why 3 knots current against 25kn wind is not the same as 28kn wind?
Hi Ignat,
Not dumb at all. That came up on the original tip: https://www.morganscloud.com/jhhtips/the-loss-of-yacht-solution/#comment-313543
In refinery control ans safety system design, we live by the Swiss cheese model. I’ve referred to it in a number of articles.
Often, a tricky aspect is making sure there is no single point failure that can take out multiple layers of protection at one stroke. At least a few of the layers need to be unrelated. Separate power supplies. Multiple people monitoring, preferably at different points. Simply puting your eggs in two baskets does not help that much if the same person is carrying them, or even if two people are walking together on the same slippery path.
Hi Drew,
Interesting, I love your metaphor. Reminds me of boats set up in such a way that a power failure makes them totally inoperable. In the case of sailboats it really worries me when the rig can’t be easily managed without electricity.
I think an important fact that emerges from the model is that safety is inherently statistical – ie, you’re relying on reducing the *chance* that the holes line up; you can’t *guarantee* they won’t except by staying home.
And, because of that, you need two very specific questions:
1. Are the risks as low as reasonably practical (ALARP) – or could I make it safer while still achieving the aim without incurring disproportionate cost?
2. Is this risk tolerable – once I’ve made it ALARP, is achieving my aim worth the remaining risk?
I did flight safety investigation as a secondary duty for the Canadian Airforce for probably close to 10 years and I can tell you James Reason’s swiss cheese model is very important for aircraft incidents. There was hardly any one cause for an incident/accident but there were less obvious things which lead up to the “holes” lining up. I definitely think about these things now when I sail (try to mitigate single points of failure as much as possible, don’t put off critical maintenance etc). I believe the swiss cheese model is very relevant to our sailing/cruising life.