Lieutenant Dan Daspit was exuberant.
The skipper was in command of USS Tinosa, which was on her second war patrol in late July of 1943.
The submarine had been lurking the Japanese shipping routes from Borneo to Truk for a
couple of weeks, and the crew finally spotted a thin trail of gray funnel smoke on the horizon.
It was the Japanese tanker Tonan Maru No. 3.
Tinosa then approached her prey while submerged and fired four textbook shots.
All the torpedoes ran true, and the crew eagerly waited to hear the unmistakable
sound of the explosions. The expectations behind the Mark 14 torpedoes were enormous,
as they were deemed the most advanced anti-ship weapons in the US inventory.
A few seconds later, the sonarman heard the projectiles’ thumps striking the tanker’s hull,
and then, the unexpected happened…
Weak Spot
The US Navy had a perfectly serviceable torpedo in World War 1: the Mark 10. But as the decades
passed and the world set the stage for the largest war in history, the decent self-propelled mine
fell behind in the arms race against the stronger and faster ships of the 1930s.
Moreover, as the design of submarines advanced,
the need for a larger, faster, and more powerful torpedo soon arose.
Design work for the Mark 14 torpedo started in 1931 with the clear intention to innovate
torpedo designs and create a new kind of explosive that could pierce through the
recently-developed underwater naval armors. As such, the developers drew inspiration from the
1920s’ German concept of magnetic mines and focused on perfecting under-keel detonation.
Although the idea might seem obvious in hindsight, it was groundbreaking in the interwar period.
Still, the advanced concept brought along many problems.
To begin with, previous torpedo models detonated on contact,
so an explosive traveling below keel depth would fail to explode.
Still, a state-of-the-art invention seemed to offer an unerring solution.
The Mark 6 exploder was a detonator conveniently activated by the change in
the magnetic field provoked by the ferrous metals in the ships’ hulls and bowels.
The torpedo carried a moderate warhead that allowed it to detonate under the influence
of a steel hull as it passed beneath it. Notably, there was no armor on a ship’s belly.
The remarkable technology was treated as top-secret and concealed from the public eye.
Furthermore, the manual with the details of the exact inner workings of the extraordinary
Mark 14 torpedo was locked away from anyone who would use the technology.
Needless to say, the supposedly original mechanism was a decade old,
and many other countries were already experimenting with similar approaches.
Still, the sea service’s paranoia and stubbornness
in the pre-war years would ripple through the early stages of the war,
unwittingly affecting the people who relied on their Navy the most - sailors and submariners.
No Excuse
As USS Tinosa encountered the tanker Tonan Maru No. 3 on July 24, 1943, and fired a few
Mark 14 torpedoes at her to no avail, the Japanese vessel turned and steamed away.
Frustrated, Tinosa’s commander Lieutenant Dan Daspit,chased after her.
The pursuit was long and exhausting,
extending through the night until Tinosa was in a position to launch an attack again.
This time, her torpedoman closely checked every piece to ensure the
torpedoes were working smoothly. Only then did the submarine fire. Both mines hit the target,
and as a muted rumble echoed through Tinosa’s hull, her crew cheered.
The tanker was forced to stop after being hit in the engine room.
But Daspit, a seasoned skipper, took his time to approach his enemy’s port side.
He used to carefully launch one torpedo at a time, at an exact angle of 90 degrees like
he was trained to do. At 1,000 yards, the commander thought only two or three
of his Mark 14 torpedoes would blast the tanker’s hull and send her to the bottom.
It was already the morning when Tinosa fired the next torpedo.
The shot was perfect, and the mine ran true. Still, nothing happened. Unconcerned,
the crew proceeded to make another shot, but there was no eruption or even a single noise.
The desperate commander then fired another two torpedoes, but they did nothing.
One torpedo only managed to raise a plume of white water,
while the other struck the tanker and broached the hull only to sink afterward.
By now, the Japanese crew was well aware of the American’s presence;
the multiple failed attempts had given them plenty of time to make a distress call.
Soon, a destroyer came to their aid, much to the disgust of the confused submariners who,
after launching the last two torpedoes to no effect, were compelled to leave the scene.
The tables had turned.
Speechless
On their way home to Pearl Harbor, Lieutenant Daspit wrote an entry in his log,
reading: (QUOTE) “I find it hard to convince myself that I saw this.”
It was simply unexplainable that 13 out of 15 torpedoes had failed to detonate,
especially considering that most shots were textbook launches.
Returning with empty hands, Daspit met with Rear Admiral Charles Lockwood,
the new Commander, Submarines, Pacific Fleet, or COMSUBPAC. The irritated skipper then retold
the story of the uncanny encounter with the Japanese as Lockwood listened attentively.
Lockwood later wrote: (QUOTE) “I expected a torrent of cuss words,
damning me, the Bureau of Ordnance, the Newport Torpedo Station and the base torpedo shop.
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.”
The single unused torpedo in the submarine was later examined at
the Submarine Base torpedo ship and found in perfect condition.
Still, Daspit’s report was not the only problematic one within the submarine fleet,
but it was the most recent and extreme case Lockwood had heard.
Going back to a week after the attack on Hawaiian Harbor early on in the war,
USS Seawolf had engaged a Japanese freighter near the Philippines,
but only one out of eight launched Mark 14s hit the target, and it failed to explode.
Despite being considered a marvel of engineering, the development brought
a litany of complications. Just in the first months of the war,
US submarines fired no less than 97 torpedoes at enemy ships, but only three were sunk.
Different Latitudes
The Mark 14 was primarily designed by engineers at the Navy Bureau of
Ordnance and built at the Newport Torpedo Station. But as the 1930s rolled on and
the demand for more ammunition increased, the manufacturer could not keep up with production.
While the Navy expected a rate of 50 torpedoes daily,
the actual amount was not even half at its most productive.
In truth, the production had a backlog of thousands of torpedoes by the end of the decade,
rendering those few completed ones inestimably valuable in the war effort.
Additionally, each piece cost as much as five times a new automobile, upward of 10,000 dollars.
Unsurprisingly, the Navy was unwilling to lose even one torpedo in a live fire test.
As such, the torpedo was cleared to enter service without almost no
evidence supporting that it was as efficient as it was thought.
Only one test of the Mark 6 detonator was conducted, with poor results.
Of two torpedoes fired at a derelict submarine, one ran under the target and did not explode,
while the other did explode and sank the vessel.
Ironically, the magnetic warhead was highly sensitive and prone to
detonate with minor fluctuations, but the developers ignored that the
ships’ magnetic field was not the only one to influence the mines.
In fact, the Earth’s magnetic field played a key role, but having tested the projectile
in a specific latitude that was different from that of the warzone, it was rendered useless.
Still, the Mark 14 became the American Submarine Fleet’s best
chance at undermining Japanese shipping even as it had a 50 percent failure rate.
Incompetence
When the first complaints came, the Bureau of Ordnance bluntly denied any issues with
their product. Even worse, they blamed the sailors and submariners for being incompetent.
However, many projectiles missed their target even when aimed with care.
Some failed to explode, while others blew up before reaching the objective.
But for all the attempts, the Bureau of Ordnance would not allow anyone to
tamper with its precious Mark 14 or even get a glimpse of the operating manual.
To further complicate the matter, the Navy eventually demanded a larger warhead,
which was enlarged to 680 pounds - more than enough to pierce through the hardest hull.
But the magnetic exploder worked too well, almost blowing up the skippers’ faces.
And despite having a backup contact detonator, it was never used.
Moreover, the heavier warhead caused the torpedo to dive too deep, seldom getting near the hull.
By the time the Bureau of Ordnance acknowledged its mistakes and fixed
the Mark 14, it was too late. Moreover, of the 53 US submarines lost in the entire war,
20 were sunk before October of 1943. It will never be known if any were lost to faulty torpedoes,
but what is clear is that dozens of patrols were wasted, hundreds of hands were lost,
and many enemy targets were left to roam the seas untroubled.
On the bright side, many other torpedo models benefitted from the lessons learned with the
Mark 14. And as Lockwood added, when the submarine commanders were finally able
to hit the targets: (QUOTE) “All major exploder problems suddenly disappeared.”
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