A matter of numbers!!
Last night, Jill and I had dinner at a restaurant/Jazz club. Ed & Ellen Zacko were there playing in the session. They are back in the USA from Spain. They sailed from the US to the Med a few times over the years, then back across, through the Panama Canal (I posted a Youtube of there trip with MrJohn), then on out through the South Pacific, They shipped their boat to France, did the canals and are now back in Seville Spain. I say this as they have a bit of experience sailing a Nor'Sea and MrJohn is a larger (40 +/- boat).
During a break we were talking about the subject. He said that John, (on MrJohn) thought safety is a matter of numbers. 10 being the best, 0 the bottom.
IF, you have sailor that is a 10, and you have a boat that is a 10 it can do most anything
IF, you have sailor that is a 10, you can have a boat that is a 5 and still go most any place.
IF, you have sailor that is a 5 and a boat that is a 5, that's a recipe for trouble.
In my mind, my thoughts, the numbers are constantly changing. You might be a #10 sailor when you are 30 or 40~ years old. At 55 to 60, you are no longer a 10. No matter what my mind might try telling me, the old body just ain't the same.
A boat might be a 10 when you depart the dock, but as the cruise progress, it may drop in number.
On the way home my mind was going over this. The bigger (say 55+ foot) boat may start out with this #10. Then you put a value on each item or system. So, waterline is part of the total number. How the craft was designed AND built is part of that number. So is that electric winch, (the electric is part of the total for the winch and the manual is part of that number). The rigging is part and so on as you like.
My thought is that while a large well designed and built boat, say 18 to 20 meter (~65 foot) boat leaves the dock a #10.
As it goes along, with a lot of systems, if one breaks down, that #10 can fall rapidly. If for instance electric is used for sails & anchoring, and you loose electric, the numbers fall quickly and the boat fast becomes a 5.
The larger the boat and/or the more complex, the faster the number can drop.
If a smaller boat, rated as, say an 8 or 9 due to shorter water line, leaves the dock, but does not have electric sail handling or winches as they are not needed, there is just not that much to lower that number.
Also, we add to that the crew scale. A crew departs the dock as a #10, but after some time, that number may drop. Break an arm and you are instantly down to a 3 or 4. Fatigue would be in this part of the equation. It has been very rare that I have become overly tried as our boat will heave-to very easy and we take a break to rest up.
Any way, just another way to look at this. I think more logical.