NTSB agreed with USCG on most likely cause.
But it is not at all clear what
the source of ignition would be
with the ship asleep and nobody in the pump room.
Another possibility is that the first
explosion was in the ER
where there are plenty of sources of ignition.
One way this could happen is vapors leaking
from the pump room.
We simply don't know.
This casualty is an argument for the old Lloyds Register
system of putting the emergency fire pump forward
with its own prime mover.
This was an LR requirement until the late-70's
when inter-class competition forced Lloyds
to go along with the other Classes
and allow the emergency fire pump
to be right beside the engine room
where it gets taken out by the same fire
that took out the normal fire pump(s).
Cutter puts spill at 5.6 MMG.
Ship was built in 1944 and jumboized in 1958.