"In the early 2000s, the Coast Guard awarded a contract to Bollinger Shipyards Inc. to convert its 110-foot patrol boats to 123-foot vessels. Starting with eight ships, the contractor attached new steel to extend the hulls of the ships by 13 feet. The results were disastrous.They should have read their Luke!
'What we found out was when you put new steel on old steel, it flexes,' Papp said. 'Those patrol boats were unusable afterward and there was a chance of a catastrophic failure.'
He told them this parable: “No one tears a piece out of a new garment to patch an old one. Otherwise, they will have torn the new garment, and the patch from the new will not match the old. And no one pours new wine into old wineskins. Otherwise, the new wine will burst the skins; the wine will run out and the wineskins will be ruined. No, new wine must be poured into new wineskins. Luke 5:36-38(NIV)Last month the Justice Department sued Bollinger Shipyards, accusing the Lockport, La., company of 'making material false statements to the Coast Guard' about the hull strength of the converted ships...
...The upgrades in question cost about $95 million and the eight boats had to be decommissioned." By ALICIA A. CALDWELL - Associated Press
Read it all here
I need to remember this the next time I am asked about remodeling the house.
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One would have thought a structural/materials engineer could have figured that out, although I know some ships have been altered/lengthened before without problems.
ReplyDeleteCheers.
I am not a structural engineer, but I know that every ship bends and flexes in the seas. I imagine a vessel designed to flex a few inches, once lengthed might flex much more if its internal skeleton and compartmentalization was not originally designed for that length.
ReplyDeleteI recall that the U.S. Navy successfully increased the beam of several of its old battlewagons after Pearl Harbor. (I think the USS Tennessee was one whose beam was increased to the point that it could not fit through the Panama canal).
This report from the Congressional Research Service does not find a single unifying conclusion, but does state:
"We believe the design of the 123-foot patrol boat reduced the structural cross section necessary to support the added weight distribution following the conversion. Our analysis has been complicated, however, by the fact that we’ve
observed permanent deformations of each hull in slightly different ways."