Tinosa made herself a second chance by chasing throughout the following day. Daspit also checked the torpedoes he had left and insured that the magnetic influence exploders had been disabled (see below for why). Even so, the first two torpedoes of the second attack had to be shot at an awkward angle and range. They hit and exploded disabling Tonan Maru's engines. With the target dead in the water Tinosa was in an ideal firing position, moving in to fire on the tanker at the submarine equivalent of point blank range. The torpedo appeared to hit its target but did not explode. Daspit and crew continued to fire torpedoes one at a time at the tanker. All of them hit, but none exploded. Daspit's log gives time of firing of each and states over and over again "fired [nth] torpedo. Hit. No apparent effect." Daspit recorded about the sixth one since Tonan Maru had become a "sitting duck", "... Hit. No apparent effect. This torpedo hit well aft on the port side, made splash at the side of the ship and was then observed to have taken a right turn and to jump clear of the water about 100 feet (30 m) from the stern of the tanker. I find it hard to convince myself that I saw this."
He took his sub to the other side of the target and fired the eighth and ninth torpedoes even as he saw a destroyer approaching from the east. As Tinosa went deep they heard the last torpedo hit and stop running. Daspit recorded in his log, "No explosion. Had already decided to retain one torpedo for examination by base." After shooting nine torpedoes at a sitting duck over almost an hour and a half 1009 to 1131, and taking time out to examine the fish in the torpedo room between shots, Lieutenant Commander Daspit took Tinosa back to Pearl Harbor with the single remaining weapon.
Daspit stormed into SUBPAC's office. He had shot 15 torpedoes at Tonan Maru over two days and only 2 of them had worked. The others shot under ideal conditions failed to explode. Rear Admiral Lockwood, COMSUBPAC wrote: "I expected a torrent of cusswords, damning me, the Bureau of Ordnance, the Newport Torpedo Station and the Base Torpedo Shop, and I couldn’t have blamed him – 19,000 ton tankers don’t grow on trees. I think Dan was so furious as to be practically speechless. His tale was almost unbelievable, but the evidence was undeniable." [7] When, upon inspection, nothing obvious was found wrong with that last torpedo, Commander Swede Momsen suggested conducting tests on actual warshots by firing them against the cliffs of Kahoolawe, a small island south of Maui from the submarine Muskallunge (SS-262). The first two exploded. The third one did not. Within a few days the cause was traced to a firing pin that was mounted athwart-ships such that when the torpedo hit a target dead-on (ninety degree track angle) the deceleration forces slowed the pin's motion in its bearings and its spring could not move it fast enough to set off the explosive train. A glancing blow, however, would result in the proper behavior (which is why Daspit's first two torpedoes, fired at less optimum track angle, did explode).
Two solutions were worked on. One involved recycling a very light metal alloy that had been melted down from the engine of a Japanese airplane that had crashed on Oahu during the bombing of Pearl Harbor. Both solutions were installed into torpedoes and the submarine force had a mostly reliable weapon 21 months after the war started.
This was the third strike for the Mark 14 torpedo. It started with the Sargo (SS-188) missing 13 of 13 easy shots in December 1941. Finally in June 1942, Admiral Lockwood, the Commander of Submarines South West Pacific (COMSUBSOWESPAC), arranged to have torpedoes – with special non-exploding warheads (but unlike the exercise heads of that time and later they were filled to make them just as heavy as the actually explosive-filled warheads) – shot at fishnets. They were set to run at 10 feet (3 m). 850 yards (780 m) away they went through the nets at 25 feet (8 m) depth. The Bureau of Ordnance (BUORD) wouldn't accept this until they were forced to face the facts and conduct their own experiment. They confirmed Lockwood's experiments on 1 August.
But that was not the end. In April 1943 BUORD admitted that the magnetic influence exploder was susceptible to premature explosions. Even then it wasn't until 24 July when Admiral Nimitz ordered that the influence exploders be disabled on all Pacific Fleet submarines. This did not apply, however, to COMSUBSOWESPAC. Admiral Christie then in command had been the officer in charge of testing the super secret influence exploder in the 1930s and he just could not give up on the concept and he ordered that his boats continue to use the defective magnetic exploder.

These 2 photos are a PDF at a party for the torpedo crew and their officer, Ensign Keith Van Gorder at San Francisco, October 1944. It was just after the FM sonar gear was installed and just prior to departing Pearl Harbor to put it into action. Van Gorder was the Torpedo Officer and was leaving the ship; dad had been under him on 2 patrols. On one patrol a torpedo got stuck exiting a bow tube and became armed because they were escaping escorts and had to move. After they escaped the escorts they surfaced and Van Gorderand an enlisted man went overboard to wedge the impeller so the fish wouldn’t go off when it wound down. He got a Silver Star for that one. They pulled an all ahead/all astern maneuver and it came loose and dropped to the bottom. Many brows wiped that day. But later they used the FM sonar to map the minefields around Okinawa and Iwo Jima. MORE brows wiped.
Dad is mentioned in the skipper’s report of patrol 8 and in Al Watrous’ book: Encounter Combat History of the USS Tinosa; a very large wave washed him out of the starboard high lookout at 03:30 on 17 December 1944 as they were approaching the Bonin’s… Got lucky and snagged a line, washed way again but made it back to the conn. Benny Bentham wrote extensive notes during later patrols, and those were included in an appendix of Watrous’ book.
First pic:
Top row- Keane, John J., TM3c, Wesner, George D, TM1c, Weeks, Clyde E., TM3c, Van Gorder, Keith R., Ensign, Clement William R., TM2c, Monroe, Jack A., FC3c, Brown, Milton J., TM3c, Goodell, George E., FC3c(SS) & Otis, Donald J., TM2c(SS)
Bottom row-
Bentham, Robert B., TM3c(SS), Burns, Corwyn s., F1c, Giuffrida, Giuseppi G., TM1c,
Second pic:
Charlie (bartender), Wesner, George D, TM1c, Weeks, Clyde E., TM3c, Poli, Jack S., EM3c(SS)s & Brown, Milton J., TM3c