The wire ropes chafed through and were replaced by chains. Then the _F-4_ was lifted from the bottom and towed inshore to a depth of fifty feet. Here a heavy storm set in and the lines had to be cast off. Six big cylindrical-shaped pontoons were then built at San Francisco and brought out to Honolulu on the cruiser _Maryland_. Divers passed fresh chains under the _F-4_, the pontoons were sunk on either side of her, and coupled together. Then the water was blown out of the pontoons by compressed-air piped down from above, the _F-4_ was raised to the surface, and towed into dry dock.
No decipherable written record was discovered inside her hull, which was filled with sand washed in through a large hole made in the plating by the chafing of the chains. But the story of the disaster was written in the plates and rivets of the vessel herself, and skilfully deduced and reconstructed by a board of inquiry, headed by Rear-Admiral Boush. Their report, which was not made public till October 27, told dramatically how the corroded condition of the lead lining in the battery tanks had let the acid eat away the rivets in the port wall of the forward tank. Salt water thus entered part of the battery, producing chlorin gas, which exploded violently, admitting more water, till the submarine began to sink by the head, in spite of the raising of her diving-rudders.
“Automatic blow was tripped, and blow valve on auxiliary tank opened in the endeavor to check downward momentum. Manœuvering with propellers probably took place. The appreciable length of time requisite for air to build up in ballast tanks for the expulsion of sufficient quantities of water resulted in the vessel reaching crushing depth.
“Seams of the vessel began to open, and probably through open torpedo tubes and seams water entered the vessel and a condition of positive buoyancy was never attained.
“There followed actual disaster. The vessel began filling with water. The personnel abandoned stations and many sought refuge in the engine room, closing the door. Under great pressure the engine room bulkhead failed suddenly, leaving the vessel on the bottom, completely flooded.”
All the boats of the “F” class had already been withdrawn from the service, by order of Secretary Daniels. Their place at Honolulu was taken by four boats of the “K” class, which made the 2100 mile voyage out from San Francisco under their own power.