Submarine Readiness

As of this writing, the US Navy has 50 attack subs and is firmly on the downward trend which has been anticipated for decades.  With an imminent war with China looming (according to Navy statements), one would assume we’re taking good care of our subs and cranking out their maintenance availabilities with great haste.

 

The fleet attack submarine breakdown, by class, is : 

• Seawolf 3
• Los Angeles  26
• Virginia  21

So, how is the maintenance doing?

 

“We’re really struggling to get submarines out on time. Over the last ten years, 20 to 30 percent [came] out on time,” said Vice Adm. Bill Galinis … [1]

 

That means 70% to 80% of maintenance availabilities ran over schedule.  That’s not good.

 

As of Thursday, 18 submarines were in some type of maintenance, PEO Submarines Rear Adm. Jonathan Rucker said … [1]

 

With only 50 attack submarines in the fleet, that’s 36% of the fleet in maintenance.

 

What’s causing the problem?

 

The earliest Virginia-class boats are among the hardest submarines to repair on time.[1]

 

“We’ve seen a significant growth in the amount of man days required in submarine availabilities, particularly in the Virginia class,” [Vice Adm. Bill] Galinis said.[1]

 

According to the Government Accountable Office, “Virginia class submarines have returned to operations almost nine months later than expected, on average; Los Angeles class submarines have taken four and a half months longer than scheduled, on average, to return to the fleet.[1]

 

What’s the problem with the Virginia class.  After all, they’re the newest submarines we have so they should have the least maintenance problems, right?

 

The Virginias were designed to operate closer to shore and with components that met rigorous NAVSEA standards for submarine safety, but were not as durable as some of the older components on the Los Angeles-class boats.[1]

 

“Where we were in the beginning of the Virginia class, we had a charge early on to build a design and build a submarine for an affordable cost to make sure we got the numbers we needed.”[1]

 

So, by their own admission, the Navy ‘cheaped out’ on Virginia class subs and now they’re suffering extended maintenance issues and, apparently, poorer quality components.  That’s what happens when you design to a business case instead of a combat case.

 

And now, let’s listen to the Navy rationalize away the problem:

 

“If you throw a rudder over on the Titanic, it takes a while for the ship to turn,” Rucker told USNI News.  “It’s going to take a little bit of time, just because there’s a lag and getting the resources or changing behavior or ensuring that we plan better for what we’re going to do.”[1]

 

The maintenance delays have been on-going for a decade, at least, admiral.  How much more time do you need to ‘throw the rudder over’?

 

 

 

________________________________

 

[1]USNI News website, “NAVSEA: Navy ‘Struggling’ to Get Attack Subs Out of Repairs on Time as Demand Increases”, Sam LaGrone, 21-Sep-2022,

https://news.usni.org/2022/09/21/navsea-navy-struggling-to-get-attack-subs-out-of-repairs-on-time-as-demand-increases

Virginia Class Cruisers

For no particular reason, ComNavOps has always had a fondness for the Virginia class nuclear powered cruisers, believing them to be one of the most attractive looking ships of the modern era.  For nostalgia sake, let’s take a closer look at them.  The class consisted of four ships, as shown below.  Note the very short service lives.  The class was the victim of the Cold War ‘peace dividend’ as their mid-life refueling was considered too costly for the time period given the collapse of the Soviet Union.

Ship	Service Life, years
Virginia, CGN-38	18
Texas, CGN-39	16
Mississippi, CGN-40	19
Arkansas, CGN-41	18

Virginia Class - As Built

The ships were 586 ft long (about 20 ft longer than the Ticonderoga class cruisers) with 11,666 tons full displacement and a crew of 579.  Wiki reports the construction cost as $675M (1990) which is $1.3B (2020) today.  Interestingly, these ships were initially classified as frigates/destroyer leaders before ultimately being labeled cruisers.

The class underwent refits in the 1980’s which resulted in the elimination of the helo and hangar in favor of Tomahawk armored box launchers.  Other additions included CIWS and Harpoon launchers.

The post-refit weapons fit was respectable for the time:

• 2 × Mk 26 missile launchers for 68 missiles (SM-1/2MR, ASROC)
• 8 × Tomahawk missile in 2 armored-box launchers
• 8 × RGM-84 Harpoon in 2 Mk-141 quad launchers
• 6 × Mk 32 triple torpedoe launchers
• 2 × Mk-45 5-inch/54 caliber rapid-fire gun
• 2 × 20 mm Phalanx CIWS
• 2 × 25 mm Mk 38 chain guns

Let’s take a closer look at some aspects of the class.

Mk26 Launcher.  The Virginias had 2x rapid fire Mk 26 twin arm missile launchers mounted fore and aft.  A pair of missiles (one on each arm) could be launched every 9 seconds.  Thus, the ship’s overall firing rate was 4 missiles every 9 seconds – a respectable rate and quite adequate for almost any scenario.  Given the Navy’s typical shoot-shoot-look engagement sequence, this rate of fire seems perfectly adequate.  Today’s VLS really offers little in the way of an effective enhanced firing rate.  What VLS offers is that every missile is available for use as opposed to having to be selected and loaded.

While the drawback of the twin arm launcher is that it has to point at the target and thus is limited to certain firing arcs, the benefit of the launcher is that it can point at the target and there is no delay as there is for a vertically launched missile to ‘tip over’ and acquire its target.  Thus, the twin arm launcher can put a missile at the target faster than a VLS, if the launcher is not masked by the ship’s superstructure.

It’s an article of faith, today, that VLS systems are vastly superior to twin armed launchers but the reality is that they’re not.  They have a few advantages but they also have drawbacks.

ASW.  The ships carried bow mounted SQS-53A sonars and, as originally constructed, a below deck hangar and elevator for one Kaman SH-2 Seasprite LAMPS helicopter.  The hangar proved problematic and the Navy was never able to achieve a watertight fit of the horizontal hatch covers.  The helo and hangar were eliminated in the 1980’s refits in favor of Tomahawk armored box launchers.  Hangar problems aside, the idea of fitting out major warships with ASW capability is highly suspect.  ASW is not the responsibility of a capital ship and no sane commander is going to risk such a ship playing tag with submarines.  In addition, the fact that the ship carried only a single helo meant that its ASW capability was not all that great to begin with.  Elimination of the helo/hangar was a good idea.  Interestingly, a proposal was made to install a vertical launch system for Tomahawks in the vacated hangar space, however, the idea was eventually dropped.

Armor.  The ships reportedly had 1 in (25 mm) Kevlar armor around the combat information center, magazines, and machinery spaces.  I don’t know the hull steel thickness and type.

Radar.  The ship’s main radars were the AN/SPS-48A 3-D air search radar and AN/SPS-40B 2-D air search radar which constituted a typical fit for the period.  These were mechanically steered, rotating units.  Given the maintenance and alignment problems with the Aegis SPY-x fixed planar arrays through the years, ComNavOps has often wondered if modernized versions of these units might not be combat-superior.  But, I digress …

Note Tomahawk Armored Box Launchers On Stern

Now, let’s do a bit of speculation, just for fun.

Nuclear Strike Group.  With the planned 11 ships of the class plus the two California class cruisers and the Truxtun, the Navy was on its way to assembling entire nuclear powered carrier strike groups.  This would have offered some significant operational and tactical advantages.  The group would have required no refueling support and could have operated at high speed for extended periods thereby allowing for rapid repositioning.  A highly mobile and self-sufficient task force would have been a significant benefit.

NTU.  The New Threat Upgrade would have made the Virginias quite formidable.  NTU, when it first came out, was superior to Aegis which would spend quite some time working out its bugs.  Of course, the Navy sank the entire Spruance class to avoid the Spruance-NTU fleet from threatening the Aegis funding.  A Virginia-NTU would have been the most capable AAW ship afloat.

One can only imagine the altered path of ship development if the Virginia-NTU and Spruance-NTU had come to pass.  It is likely that the compromised Ticonderoga class would never have come about and the Burkes might have, initially, been designed as stealth-NTU AAW ships to complement the Spruances instead of replace them.  This could have given us two focused ship classes: the ASW Spruances and the AAW Burkes instead of trying to make the Burkes a do-everything design.  The successor cruiser to the Virginias would probably have been a new design with more anti-surface capability than the Ticonderogas.

VLS Upgrade.  Had they continued to serve, the Virginias might have been upgraded to VLS at some point.  Given their size, it is likely they could have accommodated 128-160 VLS cells.  A truly powerful ship, indeed!

Note Harpoon Launchers In Front Of Superstructure

Summary

Aside from ComNavOps' personal affection for these ships, it is obvious that the Virginia class left a lot of untapped potential on the table when it was prematurely retired.  For all those naval observers and ship designers who constantly talk about extended ship service lives, this is yet another example of a prematurely retired ship class.  Premature retirement is the standard in the Navy, not the exception.  With this kind of history it is foolish to design for extended service lives.  As I’ve posted in the past, we should be designing for 15-20 year service lives because that’s all we typically get before we retire our ships.  All this planning for future growth is pure bilge droppings – it never happens!

The Virginias were wonderful ships and I wish they had been fully utilized by the Navy and had a longer service life for ComNavOps to enjoy and admire!

Anechoic Tiles

In its quest for ever quieter submarines, the Navy began affixing sound absorbing tiles (anechoic tiles) to submarines in 1980.  The tiles are an inch or so thick and are made of different layers, materials, and void spaces designed to deaden specific frequencies of sound. (1) 

Interestingly, anechoic tiles were first used on German U-Boats at the end of WWII.

While effective, the tiles have a disturbing tendency to fall off during patrols.  Tile loss reduces the effectiveness of the silencing and increases flow noise due to the “holes” left on the submarine’s surface.  The rough edges of these holes likely create additional turbulence and noise just as any rough edge or projection on a hull would.  Addressing a photo of a ragged looking USS Mississippi on return from patrol, former submariner Bryan Clark stated,

Bryan Clark, a senior fellow at the Center for Strategic and Budgetary Assessments and a former Navy submariner, said the amount of acoustic coating missing on the Mississippi "could create enough flow noise to be a sound problem at even relatively slow speeds. Also, there is enough tile missing that it could reduce the coating's ability to absorb sonar energy and make the submarine easier to find with active sonar." (3)

The Navy has formed various study groups to address the problem and have claimed success multiple times but tile loss remains a problem as this photo of USS Virginia in 2018 shows.

USS Virginia - Note the patches of missing tiles.

One alternative approach to anechoic tiles is being developed by researchers at the University of Michigan.  They are developing a “superhydrophobic (water repellent)” paint-like coating presumably filled with bubble voids which reduces drag thereby increasing speed, fuel efficiency, and quietness. (2)  The challenge, as with anechoic tiles, is to make the coating durable.

Similar research at the Université Paris Diderot in France has examined the use of microscopic bubbles in thin coatings. (1)  The bubbles dissipate acoustic energy.

In underwater experiments, the scientists bombarded a meta-screen placed on a slab of steel with ultrasonic frequencies of sound. They found that the meta-screen dissipated more than 91 percent of the incoming sound energy and reflected less than 3 percent of the sound energy. For comparison, the bare steel block reflected 88 percent of the sound energy.

To make submarines invisible to the sound frequencies used in sonar, larger bubbles are needed. Still, the researchers predicted that a 0.16-inch-thick (4 millimeters) film with 0.08-inch (2 millimeters) bubbles could absorb more than 99 percent of the energy from sonar, cutting down reflected sound waves by more than 10,000-fold, or about 100 times better than was previously assumed possible. (1)

While the experimental results are encouraging, the challenge, again, is to produce an easily applied, durable coating.  This is technology that is worth keeping track of in the future.

____________________________________

(1)Live Science website, “Thin 'Bubble' Coatings Could Hide Submarines from Sonar”, Charles Q. Choi, 4-Feb-2015,

https://www.livescience.com/49689-stealth-coatings-hide-submarines.html

(2)Popular Mechanics website, “Navy Testing Superhydrophobic Hull Coatings For Submarines”, Kyle Mizokami, Jul 5, 2018,

https://www.popularmechanics.com/military/research/a22063315/navy-testing-superhydrophobic-hull-coatings-for-submarines/

(3)Military.com website, “Navy Subs Still Show Issue with Stealth Coating”, The Honolulu Star-Advertiser By William Cole, 2018,

https://www.military.com/daily-news/2017/03/06/navy-subs-still-show-issue-stealth-coating.html

Does Every Sub Need Tomahawks?

Here is a companion piece to the recent post, “Does Every Ship Need A Helicopter?” which examined US Navy design assumptions.  This time, we’ll take a look at submarine design.

One of the seeming absolute characteristics of a US Navy submarine design is the capability to shoot Tomahawk cruise missiles.  Here are the recent submarine classes and their possible Tomahawk loads.

Los Angeles  12

Ohio SSGN    154

Seawolf      50

Virginia     12-40

Without a doubt, having the capability to covertly shoot Tomahawks from submarines is a useful capability.  But, does every sub need to be able to shoot Tomahawks?

The question is not whether Tomahawk cruise missiles are useful but whether their usefulness is sufficient to justify the expenditure of ship’s volume, the concomitant increase in cost and the resulting decrease in number of submarines built?  The volume and money dedicated to a submarine cruise missile capability could go to other ship’s functions and to building more subs.  In other words, there is an opportunity cost associated with submarine launched cruise missiles.

Let’s look a bit closer.

Tomahawk missiles add size and cost to submarines.  The size increase is 20% or so, depending on the specific sub class and version.  The cost increase is harder to determine but one solid data point is the Virginia Payload Module (VPM) scheduled to be installed on the newest Virginias.  The cost increase is estimated to be around $500M which is a 20% increase over the base cost of around $2.5B.

By leaving out the VPM, we could build one extra Virginia class sub for every five subs built.  Are the added Tomahawks worth losing one extra sub for every five built?  To answer that, we need to recall the submarine’s mission(s).

The problem with “missions” is that people tend to assemble a laundry list and then, in discussions, assign by implication equal value to every mission.  For instance, here’s a partial list of submarine missions in no particular order.

• Anti-submarine warfare
• Anti-surface warfare
• Long range strike warfare
• Intelligence gathering
• Special operations forces support
• Presence
• Cross training with foreign navies
• Mine laying
• Carrier group escort
• Area denial
• Blockade

As we examine the list of missions, we see that long range strike warfare is on the list.  Ergo, we must have Tomahawks on every submarine!  See what I’ve done, there?  I’ve equated every mission.  They are all equally important.  Therefore, they must all be incorporated into the design of any sub.  This is what we do today but it is wrong.

What we should be doing is prioritizing the list of missions.  We should be asking ourselves, what is the most important mission?  We might also ask ourselves what the most likely mission is – it’s often not the same as the most important!  If we do that then we can begin to intelligently design a submarine and make informed tradeoffs between cost and capability.

In war, a submarine’s most important mission is anti-submarine warfare according to US Navy doctrine since the Cold War – I’m talking about attack subs, SSN’s, not ballistic missile submarines.  The main job of our submarines is to eliminate the enemy’s submarines.  A close second mission, but still second, is anti-surface warfare.  Every mission after that is extraneous, in a sense.  If, by eliminating all the other missions – Tomahawk capability, in this case – we could build an extra submarine for every five we now build, would this be worth the loss of 12-40 Tomahawks (we’re talking about Virginia class subs, now)?  I suggest it would be and would be well worth it. 

Consider, of the 50 or so attack subs we’d like to have, we could have 10 extra subs if we dropped the Tomahawk capability!  60 subs vs. 50.  That’s a trade I’ll take!

But wait!  What about the loss of Tomahawk strike capability?  Well, that’s a significant loss, no doubt.  However, we have plenty of alternate Tomahawk strike capability in the form of Burkes and we could have much more if we took the retiring Ohio class subs and converted them into additional SSGNs with 154 Tomahawks each.  The subs are already built so it would just require the incremental cost to modify them to launch cruise missiles.  Wiki reports the conversion cost at around $700M per sub in mid-2000’s dollars.  Relative to ship building costs, that’s quite reasonable.

Submarine Launched Tomahawk - Is It Needed?

You’re asking yourself, how does an SSGN square with my previous mission list and stated priorities of ASW and ASuW?  Well, an SSGN has a different mission priority – pure cruise missile strike warfare – so the SSGN falls in line with the concept of recognizing what the priority mission is.

We see, then, that we could have more subs for the same cost and maintain or increase our fleet wide Tomahawk strike capability if we choose to spend a little bit more. 

Note, the cost of one LCS would just about cover the cost of converting one SSBN to SSGN.  Would you rather have one LCS or one Ohio SSGN with 154 Tomahawk missiles?

So, does every submarine need to have Tomahawk launch capability?  My answer is no.  The Navy needs to look at submarine CONOPS and rethink submarine design and numbers.  We need to abandon the every-ship-must-be-capable-of-every-mission thinking that now dominates our design philosophy.

Virginia SSN Review

The Virginia class SSN has been around for some time now and it’s worth a quick review.  The program was begun in the 1990’s as a replacement for the Los Angeles class and as a cheaper alternative to the Seawolf class.  Construction began in the late 1990’s with around 16 subs completed so far.  Construction is proceeding at a rate of two per year.

The SSN force peaked at 98 SSNs in 1987 and has been declining since.  The current force goal is 48 SSNs, however, the Navy’s various 30 year plan projections show a dip to 42-43 in the late 2020’s and a sustained shortfall below the 48 goal from 2022 – 2034.

Here’s a quick dimensional comparison of the classes.  Note the trend towards bigger boats just as we’ve observed with the SSBN(X) Ohio replacement sub which is bigger than the Ohio despite having several fewer missile tubes.  I’ve never seen a documented reason why the Virginia needs to be bigger than the preceeding classes.

Los Angeles  362’ x 33’                   4 tubes / 26 torpedoes

Seawolf          353’ x 40’                   8 tubes / 50 torpedoes

Virginia           377’ x 34’                   4 tubes / 27 torpedoes

The Virginia construction program was beset by cost overruns early on.  To be fair, that’s a characteristic of almost every Navy construction program.  The Virginia’s were envisioned to be low cost alternatives to the Seawolf but it hasn’t turned out that way with the subs running around $2.5B in today’s dollars.  Proceedings offers an article with the early cost history and states that the total obligation authority increased from $60B in the mid-1990’s to $90B+ in the mid 2000’s (4).  Here’s a partial cost history and planned budget amounts (1).

1998 – 2011  14        $2.6B (average cost for the period)

2012                 2        $2.6B

2013                 2        $2.5B

2014                 2        $2.7B

2015                 2        $2.7B

2016                 2        $2.8B

2017                 2        $2.9B

2018                 2        $3.0B

2019                 2        ?  VPM will be incorporated from this point on

CRS reports (3) that construction in FY14-FY18 will be performed under a Multi-Year Procurement (MYP) arrangement which is estimated by the Navy to produce 14% savings.  However, looking at the planned construction costs versus previous years, there is no evidence of cost savings.  Serial construction cost savings and MYP should be combined in FY14-FY18 for significant savings but the projected costs are not only not reduced, they’re anticipated to rise by $300M.

The Virginia Payload Module (VPM) is planned to be incorporated starting in 2019.  The module consists of 4 tubes x 7 Tomahawk missiles = 28 missiles per sub.  The VPM is the Navy’s response to losing the SSGNs which carry over 150 Tomahawks each.  According to the Navy, it will require 15-20 Virginias to replace the Tomahawk capability of the 4 current SSGNs (yeah, the arithmetic suggests around 16 but Navy articles suggest around 20 – not sure what the exact thinking is).  According to the CRS report (3), VPM will increase the Virginia construction cost by 15%-20% ($375M - $500M).

While the Virginia class is generally considered to be a success, there are some issues, to be sure.  From the DOT&E report (2), we note comments about the Navy’s reluctance to conduct realistic testing.

“Because Navy security rules prevent collection of useful operational test data from Virginia when conducting exercises with foreign ASW capable platforms, the Navy finished IOT&E and recent FOT&E without testing the Virginia class submarine against one of its primary threats, the foreign diesel electric submarine (SSK).”

No surprise there.  We’ve noted in previous posts that realistic testing, in general,  is a Navy shortcoming.

The overall assessment comes across as neutral or a slight improvement over the 688 class.

“Although Virginia was not effective for some of the missions tested, it remains an effective replacement for the Los Angeles class submarine, providing similar mission performance and improved covertness.”

The report notes specific problems with the Wide Aperture Arrays.

“After completion of operational testing, the Navy issued software changes intended to address the severe performance problems observed with the Wide Aperture Array.”

“… the Navy should re-evaluate operational effectiveness on a submarine with a repaired Wide Aperture Array.”

DOT&E notes that problems are propagating into the fleet due to the Navy’s insistence on meeting schedules over identifying and fixing problems.

“DOT&E assesses that the late fix of the array’s deficiencies is a result of the Navy’s schedule-driven development processes, which fields new increments without completing adequate developmental testing.”

Further testing is recommended.

“Repeat the FOT&E event to determine Virginia’s susceptibility to low-frequency active sonar and Virginia’s ability to conduct ASUW in a low-frequency active environment. This testing should include a Los Angeles class submarine operating in the same environment to enable comparison with the Virginia class.”

In summary, the Virginia program has exhibited poor cost performance although not too bad by Navy standards (of course, that’s a pretty low bar!).  With respect to performance, the Virginia appears adequate and probably represents a modest improvement over the Los Angeles class.  To be fair, actual performance data is nearly non-existent in the public domain.  My vague impression is that the Virginia is to the Los Angeles what the JSF is to the Super Hornet – a modest improvement at a hefty price.  Nevertheless, the Virginia is needed and reasonably meets the need at an acceptable, if disappointing, cost.

(1) Dept of Navy FY14 Budget Estimates, Shibuilding and Conversion, Apr 2013

(2) DOT&E FY2012 Annual Report

(3) Congressional Research Service, “Navy Virginia (SSN-774) Class Attack

Submarine Procurement: Background and Issues for Congress”, Ronald O'Rourke, 2-Apr-12

(4) U.S. Naval Institute Proceedings, “The Sweet Smell of Acquisition Success”, RAdm. John Butler (USN, Ret.), June 2011