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Precis File
SHIP NAME: Marine Merchant KEY: NUM. ENTRIES: 3
source HOCKING
type A
volume
material
dead -3
link

The American ship Marine Merchant was carrying sulphur from Port Sulphur to Portland ME, on April 14th, 1961, when she encountered heavy weather and broke in two and sank 40 Miles SE of Portland Lightship.


source USCG
type C
volume
material
dead
link http://www.uscg.mil/hq/cg5/boards/marinemerchant.pdf

Fairly good report. This was a Liberty ship built 1944, converted to a bulk carrier in 1945 by Marine Transport Lines. The Board uncovered a number of problems:

  1. The ship had had at least three groundings. The USCG does not feel this was important. [CTX concurs.]
  2. The ship had a history of wastage. The USCG does not make much of this; despite the fact that in November, 1957, a USCG inspector found and emphasized "working" in various parts of the structure. And he found lots of wastage in the bottom plating. "Vessel grooved all the way across and at turn of bilges between frames 86 and 87. Vessel grooved all the way across but not into the bilges between frames 68 and 69." "Vessel has recently experienced heavy weather and bottom damage has apparently been caused by this recent heavy weather." Some of this steel was replaced at this docking.
  3. This was a five hold ship. All the sulphur was loaded into Holds 2, 3 and 4 which was legal (and apparently standard MTL practice) but ended up with a sagging moment four times that had the ship been loaded evenly. Also resulted in heavy loading of the inner bottom. The ship split "just forward of the forward part of the No 3 hatch coaming at about frame 73." Ship was hove to at the time.
  4. Up to Force 10 winds. Heavy easterly swell for at least 20 hours. Air temp of 37F, sea temp of 44F.
The Board concluded the main problem was brittle fracture. The Commandant disagreed, focussing on the strange loading pattern. Supporting the Commandant's position, the main deck plating held the two halves together for about six hours, working ductilely which allowed the crew to stay on board until daybreak.


source CTX
type A
volume
material
dead -3
link

CTX agrees with the commandant that this was probably not a brittle fracture, at least not primarily. The failure almost certainly started at or near the bottom, and the sea water temperature is too high. It is also obvious that the loading pattern, aimed at speeding up loading and dishcharging was imprudent. But it is important to note that this apparently was the ship's usual loading pattern, which means high bottom stresses over a prolonged period of time. It is not clear what the inspector meant by "working" but it has to be some combination of deformation and fatigue cracking. This structure was not in good condition and was being pushed very hard. CTX think the USCG should have given more emphasis to fatigue and corrosion than it did.

MTL ships have a history of structural failures.