Merchant ships are not designed, nor manned, for multiple compartment flooding, fire suppresion, and loss of power concomittantly. CG and USN vessels are much more compartmentalized due to the anticipation of damage control. And merchant ships also do not carry an extra 100 men with little to do other than be trained, and so are not available in an emergency situation.
And if CGMojo thought that that Master abandoned ship precipitously he is willfully ignoring the fact that all lives were saved and the ship sank in short order thereafter. A rudimentary knowledge of ship construction (available within the pages of Baker's Introduction to Steel ShipBuilding, originally published in '43) would reveal that the vessel was likely constructed under SOLAS convention as a two compartment, or possibly three compartment, vessel. What that means is that the ship was designed to be able to withstand flooding of those numbers of compartments and remain afloat. By comparison, the average freighter is a one compartment vessel. Given those design parameters, and we do know she was designed and certified for polar waters, it's most likely that the damage reports the Master received impressed upon him that the saving of the ship was unlikely and that his primary efforts should be expended in lifesaving. And that judgement proved to be correct.
The idea that a ship can be drydocked, inspected, and serious hull or plate deficiencies missed is not at all impossible and probably more common than not. As a practical matter, one could X-Ray a sample of every plate on the ship and still not reveal serious deficiencies. And nothing approaching the X-raying of every plate is even attempted. Areas of common concern to all ships are inspected thoroughly and usually give a decent indication of the overall fitness of the ship. It's just the nature of the beast. All those old buckets I sailed in, that were perpetually sinking, were annually drydocked and inspected as well. None of which stopped them from sprouting new leaks at any time. And some leaks be worse than other leaks. (g) It would be unusual, with a 1969 launch, to have weld cracking, but not unheard of. Crack arrestors were still commonly used in those days as the welding technology was still not to the level of trust we put in it today. The bottom of the hull, except possibly along the keel plate, would not have had crack arrestors (rows of rivets) installed. If damage was sustained and a weld crack started, it could very quickly threaten the life of the ship. Older welding technology, most identified with WWII but later also, involved welds that, if cracked, responded like a piece of glass etched with a line and then stressed. The crack just keeps running, changing course with the plates.
The only future evidence I would expect to be forthcoming would be that of Master and crew. I doubt the yard will have much to offer and it would be highly unlikely and very expensive (2 intimately related factors) to conduct any type of underwater survey. And, she was an old ship.
Val-please keep us updated as this will probably be followed more closely in your local new sources.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.