This ship was the ex-Fort Mercer (see 19520218_002),
a T2 which broke in two off Cape Cod.
Everything forward of frame 59 was new,
and she ended up with an extra row of tanks,
and a grt of 11252.
The ship was in ballast from Portland Maine
to a drydocking in Jacksonville.
They were tank cleaning for the docking
putting the slops into 8C.
The previous cargo was a mixture of gasoline,
kerosene, and fuel oil.
At about 1930, the crew stopped work for the day.
At 2315, there was an explosion in way of the 8's.
But the fire immediately went out.
The explosion clobbered the deck and side shell
but the two halves were held together by the bottom.
The crew ballasted some tanks to reduce hog and a port list
but at 0345, the two sections split apart.
Winds were SW 12 to 13 knots, visibility 7-8 miles.
The sea was moderate with a SW swell.
Air temp was 49F, water temp 42F.
The crew forward launched the starboard lifeboat
but the steward had a fatal heart attack
while attempting to trip the releasing gear.
This was the only casualty.
The port forward lifeboat could not be launched due to the damage.
Both sections were towed to Newport News
and inspected by the USCG in drydock.
They found considerable wastage
but that was not deemed causal.
Nor was the fact that there were known cracks
and faulty welds in way of No 8 tanks.
Nor was the fact that there was known
leaks between 8 wings and 9 wings
in the top section of the 8/9 transverse bulkhead.
And there were leaks between 8C and 8S.
To quote the report
"While these cracks and leaks had been known for some time,
they were considered as routine in tanker service
and were not considered important".
The USCG found no evidence in the ruptured steel
that a structural failure had preceded
3, 5, 8 across and 9 port and stbd were
used as ballast tanks and fitted
with magnesium anodes.
The USCG found these anodes badly wasted,
and several remnants of anodes on deck.
The crew had removed these during the tank cleaning.
The crew had a policy of removing anodes
that looks like they were about to fall,
but only the ones they could get to easily.
Finding fallen anodes was not uncommon.
Magnesium anodes can easily generate a spark
when they hit steel.
The USCG concluded that by far the most likely
cause of the explosion was that one of the
anodes in 8C, not gas free and being used for slops,
had fallen, and ignited vapors in the tank.
As a result of this casualty, the USCG
banned magnesium anodes, a ban that was eventually
extended to the whole tanker fleet.