Originally Posted by Chrisgo
It is, and I agree with your comments about the 5 digits - I assume they did a test and then reported the exact number as a marketing ploy so as to be viewed as 100% honest. I am sure a rounded number would suffice. But they did publish a number, and as such would stand by it in a court of law should that need occur - so there must be some amount of confidence in the build.
I'd be curious to see how they came up with that number.
How was it measured? What direction was the force applied in? Is it just a calculated number or an actual test to destruct? How many stress cycles at that amount of load?
Let's just say I've had some pretty optimistic numbers thrown at me by some of the engineers in my company that had no relation to applications in the real world, I knew they were BS numbers just from experience. If it is just some number sighting the break strength of the securing bolts the number is total rubbish, it doesn't really say what the deck
is capable of supporting. I've had a number of production boats over the years and would bet I could pull the cleats right out of the decks of those boats with 8000 lbs of force applied in the right direction.
On the production boats I've owned, most of which are several generations removed from that one, I added backing plates to the bow and stern cleats when there were none, of course those boats had through bolted deck hardware
so it wasn't a big deal to add them.
I'm not so sure I'd feel comfortable with glassed in backing plates which were tapped to receive the anchoring
bolts and surely don't trust deck hardware
secured with fender washers. I guess it depends on what your using the boat for.
Moorings are a whole nother issue, if they're too tightly packed with short mooring lines and just enough chain for tidal changes you can certainly get some pretty violent shock forces when the whole assembly goes tight. Kind of the same reason I like to use a long snubber lines on my anchor chain to act as shock absorbers in rough weather
It isn't just one piece but all the pieces of the mooring setup that contribute to excessive loads, in this case I'm sure there were several contributors to the cleat failure that set the chain of events
No, ripping out a bow cleat won't sink a boat, but turning it stern to the seas and allowing it to swing into other boats or moorings will.
A good friend of mine kept his boat in a mooring field that was well protected from the prevailing southwesterlies but wide open to the northeast, this isn't a problem during the summer season but is on both ends of the season when noreasters roll through.
After two seasons in that mooring field we noticed stress cracking in the deck around the bow cleats used to secure it to the mooting lines, fortunately we found it before any failure occurred and were able to beef up the entire area and reinforce the structure. He also added more heavy chain to the underwater portion of the mooring as well as longer mooring lines made out of three strand instead of double braid. These had more give to them and the heavier added chain helped to dampen the forces. The stress crack issue did not return after that, the boat was kept on that mooring 5 more years until he sold it.
Just for shits and giggles we rode
around the mooring field in the dinghy
looking at the cleat mounting areas of quite a few boats there and saw a number of boats with the same kind of stress cracking around the bow cleats, we left notes on several of those boats just to give the owners a heads up, only one called us.
When tropical storm Sandy came through awhile back (it degraded to a tropical storm by the time it hit RI) one of those boats ended up on the beach.
A Westsail 32 I bought and sold a number of years ago was finished by the original owner who put a substantial sampson post on the foredeck, at the time I thought it was just for the sake of traditional styling and never gave it a second thought, but now it's looking better and better all the time.
Most production boats I've owned weren't really built to ride out a tropical storm at anchor, it's just not what most of them will ever see in the real world, but, with some modification there quite capable of doing so. If you've got more skill and ability than money I'm sure you can address the weak points, you just have to find them and address them before they become a real problem.
I think I need to go inspect the cleats on my boat.............