A few more points in response to some confusion and to clarify some technical points:
1) There have been no known weld or catastrophic shaft failures on Rockna anchors that I'm aware of. I photographed the welds on the two anchors after assuming that one was of Canadian Providence "CN" and one that was definitely "Made in China"
Sloppy welds can be very very strong - traditional (Chemical flux shielded stick welds) can be VERY strong, if quite unattractive. I know - I fabricated many bits and pieces for my race
car (yet another topic) using a stick welder. Even a properly brazed joint will be incredibly strong - but hand welding is an art as much as a science, and the skill of the welder plays an important part, as do numerous other factors, including the preparation of the base metal, weld wire quality, flux moisture content, ambient temperature, etc, etc, etc....
After the 1994 Northridge Earthquake (a "mere" 6.9) struck Los Angeles, countless modern welded frame steel mid and high rise structures experienced brittle weld failure due to Lincoln Electric
having substituted poor quality electrode wire for dozens of years. These joints would have failed catastrophically had the shaking continued for another 30 seconds, or been more intense, or followed by another aftershock of equal or greater magnitude:
behaved exactly how Rockna is behaving - though putting millions rather than merely thousands of lives at risk. The city of Los Angeles ultimately outlawed the substandard weld wire, and required retrofitting and rewelding of all suspect structural connections under it's jurisdiction - at great cost to property owners.
I saw this sort of thing ALL THE TIME AS AN ARCHITECT and finally quit the profession - though it was my life's work
I refuse to participate in or look the other way at corruption - especially corruption that endangers life and limb - but again - that's another topic.
So the anchor welds are not the point, though they are critical - it's that they serve as a visual marker for QUALITY CONTROL at Rockna.
2) Regarding metallurgy: I assume the figures being quoted 800 vs 600 are for the tensile strength of the steel being used. If so, we have a 25% reduction in tensile strength. I'd like to see the engineering calculations and finite element analysis assumptions, models, and figures that led Rockna executives and/or engineers to conclude that it was safe to downgrade thier steel and risk my life and boat
That said, metallurgy is a complex topic. While I'm versed in the basic, I'm not a metallurgist, and would need to defer to one to evaluate the properties of the lower tensile alloy as it applied to the expected loading on an anchor shaft.
Metallurgy always involves trade-offs - increases in the harness of steel are mainly achieved by adding carbon to the alloy, which also increases it's brittleness. Alloys developed for high tensile strength are numerous, and exhibit different trade
offs between cost, corrosion
resistance, ductility, etc, etc, etc.... In the US structural and architectural steel is graded by the ASTM - and there are literally dozens of different grades:
Automotive steels have thier own organization and standards: SAE:
And of course, Europe
has it's own standards:
Note that all these are "standard" grades, and can be tweaked by metallurgy during manufacture to achieve a dizzying array of properties.
Ever hear of "Corten" steel?
Yup - it's a structural steel who's metallurgy is designed to make it RUST quickly, thus (supposedly) protecting the underlying steel!
US Steel's headquarters are (famously - to architects like me) made of the stuff! It was very popular in the 60ies and early 70ies, until several large buildings had to be demolished when it was discovered that rust does not always protect the underlying steel.
So this stuff is not well understood - even by so called experts. It's stupid and dangerous to arbitrarily substitute a different grade of steel on a heavily loaded structural element in a well proven design without extensive engineering studies and testing that verify it's prudent to do so.
So it's very simple to this observer:
A sailor copies an existing design (the Bugel) and then modifies and improves it down in New Zealand
. His product is excellent, and slowly becomes trusted by the cruising community.
Then he sells out for a dump truck full of cash to the highest bidder - perhaps retaining a financial interest in the company perhaps not.
Said high bidder is a lowlife, a bilge
rat, who like most people driven by greed, would probably sell his own children
into slavery if it meant he could drive a more expensive car or buy a slightly larger Lear jet.
To accomplish this, the bilge
rat fires the old staff loyal to the original inventor, and hires out manufacturing to the cheapest cut rate Shanghai child labor sweat shop he can find, and it's unskilled labor pool welds together crude approximations of the original developers's design out of the disgarded dog food
they are fed out of by the Shanghai sweat shop bosses.
Meanwhile, Developer and Bilge Rat meet in San Tropei over Dom and caviar to toast thier mutual prosperity and business acumen.
And Rockna anchors the world over start bending and failing to reset in the extreme conditions they are marketed for....