AVS is a Moveable Feast

[Laser310]

what percentage of sailboat losses are due to a lack of stability?

...and i'm not counting the keel falling off

very very few.

i think it's over-rated as a safety issue.

 

[Never Grumble]

I still have a collection of naval architecture books if anyone would wish to borrow.

 

[Mark-1]

what percentage of sailboat losses are due to a lack of stability?

...and i'm not counting the keel falling off

very very few.

i think it's over-rated as a safety issue.

Although likely relevant in the specific case we're discussing in this thread.

 

[flaming]

what percentage of sailboat losses are due to a lack of stability?

...and i'm not counting the keel falling off

very very few.

i think it's over-rated as a safety issue.

I can think of a few.

However, the focus on that aspect of boat design since the fastnet review, and the drafting of rating rules that encourage stability, has meant that most boats who head into tougher conditions are pretty good in this respect.

 

[Laser310]

Although likely relevant in the specific case we're discussing in this thread.

i am not saying that any AVS is acceptable, or that it is completely unimportant..., and the case of a yacht with exceptionally low AVS - much lower than probably any modern cruising yacht, isn't really very cautionary.

Probably the only sailboats out there with such low AVS are older "traditional" boats.., maybe some tall ships, and so on.

 

[Laser310]

I can think of a few.

However, the focus on that aspect of boat design since the fastnet review, and the drafting of rating rules that encourage stability, has meant that most boats who head into tougher conditions are pretty good in this respect.

On the other hand.., the Pogo 50 (carbon rig, 3.5m swing keel) does not meet the Stability Index requirement for the Newport-Bermuda race - the boat would need a shoe added to the keel.

I am pretty sure I would have no qualms about sailing a Pogo 50 to Bermuda.

The Bermuda race just lost 3 boats in 2024.., none were due to stability issues.

maybe we are still fighting the last war...

 

[flaming]

On the other hand.., the Pogo 50 (carbon rig, 3.5m swing keel) does not meet the Stability Index requirement for the Newport-Bermuda race - the boat would need a shoe added to the keel.

I am pretty sure I would have no qualms about sailing a Pogo 50 to Bermuda.

The Bermuda race just lost 3 boats in 2024.., none were due to stability issues.

maybe we are still fighting the last war...

Just because you aren't losing boats to stability any more, doesn't mean you should stop doing the things that seem to have worked....

The reason that Stability is given such a high profile is, I think, because when it becomes an issue it does so in a way that means you can go from ok to total loss very quickly indeed. Unlike other failures where you probably get more time to sort out a life raft etc.
See the report into the Bermuda sinkings for example...

 

[Supertramp]

It’s a little bit dated but orders of magnitude it’s right - roughly 500K people die in the U.K. each year (pre covid), roughly 2000 of them on the roads - so 1:250. Of course if you did the analysis by age group you’d get different ratios. As you would with genders.

Translating it to boating risks is harder - almost all the population frequently drive/cycle/cross the road etc so no need to factor that in. You’d need to consider the participation denominator. But then just as with the roads you’d need to consider different types of boating - eg transocean racing versus rowing on the local lake.

The 1 in 250 applies to those who die in a year. The chance of dying in a road accident (UK) will be more like 2000 in 68,000,000 or 1 in 34,000. Subject to lots of averaging caveats.

 

[Supertramp]

I have a pilothouse deck layout which allegedly increases the AVS. Until the windows pop. Lot more to this than just one measure.

 

[Mark-1]

The 1 in 250 applies to those who die in a year. The chance of dying in a road accident (UK) will be more like 2000 in 68,000,000 or 1 in 34,000. Subject to lots of averaging caveats.

Some of us hope to live more than a year though! To get the lifetime chance you have to divide that 34,000 by life expectancy.

I think the Highway Code got it ball park right for the point there were trying to make, and it's adequate for QI facts.

Now HC breaking distances, they are a total lie.

 

[Supertramp]

Some of us hope to live more than a year though! To get the lifetime chance you have to divide that 34,000 by life expectancy.

I think the Highway Code got it ball park right for the point there were trying to make, and it's adequate for QI facts.

Now HC breaking distances, they are a total lie.

You are right on both counts. Perhaps another way to consider it is how much planning and thought goes into making a sailing journey safe versus making a journey by car. I think we assume that the car designer, road builder and other motorists will all conspire to keep us safe on the road whereas the buck stops with us at sea, perhaps along with the yacht designer.

 

[ylop]

The 1 in 250 applies to those who die in a year. The chance of dying in a road accident (UK) will be more like 2000 in 68,000,000 or 1 in 34,000. Subject to lots of averaging caveats.

It’s the proportion of people who die in a year on the roads as opposed to other causes. Assuming it is constant over time it will be correct - 1:250 deaths in the U.K. is on the roads. It sounds a lot but actually it says you are much more likely not to die on the roads than on them. But it’s perhaps frequent enough that you should pay attention to the risks.

There were about 250 people in my year at secondary school. It means by the time we all die, we would expect one of them to die on the roads, and the other 249 to die of other causes. That feels about right: about 10 will die in some sort of accident/trauma (including RTAs), the other 240 of natural causes. It doesn’t tell you when you will die. It doesn’t tell you that in any particular year that it will be the case (at 20 it’s far more likely that your classmate dies in a road accident than of heart attack; at 80 it’s far more likely that those who have lived that long dies from disease).