A $440 million dollar warship that was supposed to intercept drug smugglers,
ironically, now has a “crack problem” herself! The bigger issue is that this is not just a one-off.
Almost half of the Independence-class littoral combat ships have been developing
cracks on their hulls since late 2019, but it wasn’t publicly known until a few days ago,
when records were made public that detailed the extent of the problem. But why these ships now
have to check the weather forecast before going on a mission, is Not What You Think!
The materials used in airplanes, ships, and almost all structures are subject to stress. Of course
if designed and built properly, structures can go through millions of cycles of stress
without cracking. But once a material is fatigued, micro-cracks start to develop and
propagate which can result in … magic tricks! Magicians have been bending forks and spoons
for quite some time, and even though this fork seems to be as hard as Chinese algebra,
before you know it the magic is going to happen right in front of your eyes!
I know you thought I was just a pretty face, but thanks to metal fatigue,
sleight of hand, and numerous hours spent on YouTube, I can now do this!
But metal fatigue has also led to catastrophic accidents …
In the early 1950s, the deHavilland Comet, the first commercial jet airliner to carry passengers,
had multiple fatal accidents, due to catastrophic decompression mid-flight.
A series of tests and Investigations ultimately determined that the cause was metal fatigue,
arising from the constant pressurization and depressurization of the aircraft’s fuselage
during everyday use. The supports around the windows had been riveted, not glued,
which is thought to have initiated the cracks that caused the fuselage to fall apart. The fuselage
was also experiencing considerably higher stresses than anticipated around the sharp corners of the
Comet’s square windows, which is why passenger airplanes now have windows with rounded corners.
During WWII, American shipyards built more than 2700 Liberty ships, which translated
to an average of 3 ships every 2 days! But many of these ships developed cracks on their hulls,
and in some extreme cases, the ships split in half
without warning. One might attribute the cracking issues to the workmanship.
Afterall, each of these ships were built in a mere few weeks. But the problem had to do with welding,
which was extensively used on the liberty ships for the first time. Below a certain temperature,
steel becomes brittle, and as the Liberty cargo ships would transit the cold North Atlantic,
the steel at the welded joints could not absorb the forces, causing them to crack.
Back in the early 2000s, the US Navy proposed building a family of fast and
modular surface combatants to operate in the littorals. The Littoral Combat Ships
came in two flavors of Freedom and independence.
The Freedom ships have been dealing with a class-wide defect with their complex combining
gear systems, which significantly limited their speed and frequently broke down, and ultimately
was a major factor in all active Freedom-class ships to be slated for decommissioning.
The modular concept was scratched even earlier as it was not logistically feasible.
The Independence class had a rocky start too. The lead ship of the class
had aggressive disintegration due to galvanic corrosion, because the independence-class ships
have aluminum hulls. Austal, the manufacturer, made changes to the remaining ships which seemed
to resolve the corrosion issue. But in May of 2022, The Navy Times obtained documents
that revealed class-wide structural defects on the Independence-class, leading to hull cracks.
The document was in fact a temporary standing order for USS Omaha. The temporary standing order
mentions stress in certain frames of the ship to be the reason for the metal fatigue which has
caused the ship to crack in numerous places. Until the structural issue can be addressed,
in order to prevent and minimize the cracks from propagating, the ship has been slammed
with operational restrictions at different sea states, which can completely paralyze the ship.
Sea States describe the general condition of the surface of the open water.
Sea States are numbered 0 to 9, where 0 represents calm glassy waters and 9, which I’d like to call
“Extreme Puke”, is when waves get over 46 feet high . According to Omaha’s Temporary Standing
Order, she has to altogether avoid operating in sea state 5 or higher. Sea state 5 falls
under the “rough weather” territory, and even though you might feel sea sick if you were on
this fishing boat, you would still be safe. Keep in mind that this fishing boat is only 91 feet
in length. But an Independence-class ship is 418 feet long, almost 4.5 times larger in dimensions.
For a warship like this to be ordered to avoid operation in sea state 5 or higher, is a big deal.
But even in sea state 4, which is quite common in the ocean, the ship has been ordered to reduce
its maximum speed to 15 knots, which is slower than the cruising speed of passenger ferries.
This is in contrast to the advertised maximum speed of 44 knots for the LCS class.
USS Omaha also has been ordered to avoid bow and beam seas. Basically she should
avoid going head on into waves and try not to get hit on the sides. This is because
the movements of the ship as it encounters waves can cause the hull to further crack.
When the ship has to conduct Underway Replenishment,
the speed could be increased to 18 knots, to keep up with the replenishment ship,
but then it has to be dropped back to 15 knots or less after replenishment has been completed.
These restrictions mean that the ship's operations are going to be very much dependent on the weather
forecast. If it seems like some mild storm is on its way, USS Omaha has to slow down, or even
delay her trip. This in fact happened in October of 2021, when a scheduled voyage from San Diego,
California to a maintenance yard in Everett, Washington had to be postponed several times
due to the scheduled availability of the maintenance yard and ultimately the weather
conditions in the Pacific Ocean. But the Naval Sea Systems Command or NAVSEA insists that the crack
issue is not hindering operational requirements at all. We’ll let you be the judge of that.
In addition to the operational restrictions, the standing order also requires extra work
for the maintenance staff, who need to perform daily checks to identify,
mark and date new cracks, and also monitor the growth of existing cracks.
Any crack that grows to over 6 inches in length, has to be reported to NAVSEA.
But all this said, this is not the first time that US Navy warships have cracked.
Back in 2010, Defense News reported that more than 3,000 cracks had been found
across the entire class of Ticonderoga cruisers, specifically on their aluminum superstructure.
The Perry-class of guided-missile frigates which had over 20 ships also experienced persistent
cracking. USS Perry, the lead ship of the class developed cracks in her aluminum superstructure
after undergoing shock trials! But even though she required frequent repairs, it didn’t impact
the overall readiness of the ship. We are also talking about a ship that was built in 1976, as
opposed to USS Omaha that was built in 2015. You’d think a few lessons would have been learned in the
meantime, because there seems to be a correlation between cracks and aluminum superstructures.
You don’t have to wait for seamen to fall through the cracks before cleaning things up!
I know it sounded wrong but it’s right ! The Independence ships need to be repaired,
and Austal apparently has a fix in mind. Austal has and continues to make a lot of
money building the Independence ships for the US Navy. In 2021, Austal USA reported their margins
from shipbuilding to be over 10%, and they have been reporting record profits for the company.
But it is still unclear how much the fix for the independence ships would cost,
who is paying for it, and when the fix can be implemented. Sub Brief did a great job
covering this story and Austal’s financials in more detail, if you are interested.
Given what happened to the Freedom class, and the overall lack of success of the LCS program,
I would not be surprised at all, if within the next couple of years,
we start hearing rumors about decommissioning the Independence class of littoral combat ships.