ROVs Provide Eyes Under Water
Early in the morning on July 18, 2001, the ROV located the sunken vessel under 400 feet of water approximately 200 miles northwest of St. Paul, Alaska.
As the vehicle surveyed the wreck, it found that the aft starboard door in the processing space was open and the guillotine closure for the starboard discharge chute was more than half open.
Unraveling a Mystery
Because there were no survivors or surface evidence to reveal what happened, the Coast Guard’s Marine Safety Center conducted an analysis that suggested the vessel likely flooded rapidly through the open door in the bulkhead of the processing space, galley, and engine room, through non-watertight doors.
It is likely that the vessel lost all positive stability between one minute forty seconds and two minutes forty seconds, and sank in as few as four minutes six seconds after the progressive flooding began.
Recreating the Tragedy
The layout of the vessel increased the likelihood of the progressive flooding from the processing space. The door leading from the processing space to the aft deck was far outboard on the starboard side, which would have reduced the heel angle at which water would enter the processing space.
The doors leading forward into the galley and engine room were also located on the starboard side. The angle to starboard caused by the inflow of water through the aft door combined with the free surface effect inside the processing space would cause the water to spill forward into the galley, into the engine room, and eventually into the fish hold.
Likely causes of progressive flooding into the processing space:
- a wash-up hose was left on or the water supply from the plate freezers may have caused the processing space to flood internally,
- the processing space could have flooded by boarding seas flooding from the aft deck,
- the space could have flooded through the open aft door if the vessel had rolled to starboard by at least 23 degrees.
No matter the means by which the water entered the processing space, the subsequent stability would have been reduced and the flooding continued until the vessel sank. Had the processing space been weathertight, the vessel would not have sunk.
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Full article is available at http://www.uscg.mil/proceedings/summer2010.
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