Originally Posted by a64pilot
Maybe a better question is how do you determine that a keel bolt has gone through 99% of its fatigue life? (...)
I believe the case is (or at least bbc says so) of bolts known to be broken before they departed the UK for their trip to the other side.
A short reply to "how" is you make the bolts so that the NEVER EVER get even close to 99% in foreseeable use of the boat (say 100 years or so). Quite easy and inexpensive as the bolts are made of steel
rater than gold.
Look at some 50 years old grp boats - their keels are still on. If building like that was possible before (before we had CAD and computer assisted stress calculations) it is clearly still viable today.
And it is not so much a designer
problem as it is the problem of the person who selects a tool for a job. That's you and me.
Here - 11 pairs of 12mm bolts, ballast slab 3000 pounds. Boat designed in Sweden
1967. These bolts live in keel pockets and can be easily accessed and replaced at any haulout.
So, this is the short and the long of it. There are many ways to build a boat. Nobody force feeds flimsy keels into our throats. We choose our boats.
Very sad lives were lost
while the tragedy could have been avoided.