Extending Hull Life
Here's a quick discussion over at DoD Buzz about the Pentagon finally admitting what everyone has known for years -- the size of the U.S. submarine fleet is going to drop below the minimum required to support its missions by 2030. Of most interest to me is the consideration of keeping some boats in commission longer. Excerpt:
But that may be difficult, cautioned a top naval analyst. Shipbuilding expert Ron O’Rourke of the Congressional Research Service, appearing after Blake before a panel of the House Armed Services Committee, warned lawmakers that it may be hard to extend the service of the Navy’s fast-attack subs because of limitations on the lives of their pressure hulls. The Navy keeps its nuclear submarines in excellent condition, but the ships were built to meet exact tolerances and specifications, and it may be more expensive than it’s worth — or even impossible — to keep submarines sailing for much longer than their planned lives.That's really the whole problem with extending submarine lives -- unless they come up with a method of annealing the entire pressure hull, they're going to have to reduce some of the engineering margins built into the design. We all know that American submarines are incredibly over-engineered, but at some point you're going to have that catastrophic failure as you try to push the limits, and a submarine crew will pay with their lives.
What do you think? Are there reasonable methods of extending submarine hull life without unduly risking the crew? (If you bring up some sort of depth limitation, please remember not to mention any numbers below 800 feet.)
posted by Bubblehead at 5:23 PM
43 Comments:
Problem is, if you start limiting depth, or worse, the depth/speed envelope, which would inevitably result from limiting TD, you've made it a lot easier for the up-and-coming bad guys (cough *PLN* cough) to find and kill you.
Sorry, but better to build survivable boats than extend the lives of ones which may or may not be capable of handling/neutralizing newer, quieter designs, including diesels and other conventional boats.
6/01/2011 7:05 PM
The AF has been dealing with similar issues for years with old airframes like the Buff and C-5. Navy can probably learn from them. They know how many airframe cycles (with wing loading etc.) they designed for and by tracking it carefully, can operate closer to the actual design rather than having a lot of margin built in.
So, just like we track reactor effective full power hours, we could start tracking hull loads relative to design. Would mean tracking depth, rate of change of depth, and maybe operating temperature in order to compare actual operating conditions with the design life. It might also mean considering some "effective full depth hull cycle" in operations just like EFPH. No one runs around at flank and perhaps just being judicious with the number of depth cycles plus careful tracking could significantly increase effective life.
6/01/2011 7:22 PM
We could restrict the 688s to the speed/depth capabilities of the 774s..... That might help. Or just try to identify which boats have been beaten the least, and focus on extending the lives of those.
6/01/2011 7:47 PM
Out of the box idea - put a few boats in layup.
Extend the length of overhauls/ship yard periods to reduce the cycling on the hulls. Or just consider parking it in a dry dock somewhere (plenty of those just lying around right?? err maybe not) for 2 - 3 years with minimum manning.
According to the numbers we have more boats then we need right now right???? [sarcasm]
6/01/2011 8:05 PM
Define "unduly risking the crew"?
Maybe we make some operationally limited boats and have them do local training, etc. I.e. keep them close to home.
Or, make the hard decisions and decide what missions are critical and which ones are just important (or nice to have).
6/01/2011 8:05 PM
This is really going to come into play if we end up backing of on VA class to 1/year. I think this has a moderately high probability of actually occurring.
6/01/2011 9:12 PM
While the problem is real, I think it is worth having a discussion about whether or not "the minimum required to support its missions by 2030" is accurate. How much of that mission was created to justify budgets and keep the fleet from shrinking further? How many of those goals are truly mission critical to national security, or are worth their expense? My hunch is that we can do with less than we say we can. This isn't a problem unique to the sub force, but it's not one they are immune to either.
We unquestionably can't meet mission requirements as they are currently envisioned, but I don't think it's wise to take the mission requirements as gospel.
6/01/2011 10:40 PM
Where's that peace dividend we all heard about? Oh yeah, the Fed just printed it to double-down on Wall Street.
6/01/2011 10:42 PM
Hull life is not the big item. It's core life. These 688 reactors only have so much uranium in them and so many EFPH. So to stretch the life, the operational commander would not be able to use them on the typical optempo. Therefore they are not an effective ship in the force.
I know we looked at this as potentially acceptable if your requirement was based on surge only. I.e. keep them CONUS and operate only for proficiency [break glass in case of war].
The other item is that we've already looked at pushing out the hull life based on the amount of time the ship spent on the blocks during its existance. Only pushes it out a couple years, but may get another deployment out of them if they have the fuel to do so.
6/02/2011 12:04 AM
There's a whole host of missions that occur in Litorial areas that do not require deep diving. I surmise a number of ships could be constrained by depth and still be very effective in these crucial mission areas. Same with various drug interdiction missions. Who cares how deep they go.
Tom
6/02/2011 4:56 AM
So I live in the aircraft engine world now. They have life limited parts in the engine that have to be tracked and replaced when they approach their quoted (FAA approved) lives.
On engines that were certified as little as 10 and 15 years ago, the assumptions were done deterministically - meaning just add up all the bad stuff that can happen and that is the limit - a worst case. As data gathering, measurement and statistical tools improve, the approach has become more statistical. What are the probabilities of these "bad" things actually happening and them happening at the same time as other "bad" events. This results in a more realistic assessment of how long a life limited part can stay in an engine while maintaining the safety of the plane and engine.
The same can be done with EFPH and hull life. It would shock the hell out of me if hulls and reactors are not designed and lifed in a deterministic (worst case) sense. I am not saying it doesn't keep things safe. But what it does do is drive a lot of cost, weight and concessions into a design - limits the depth, the life of the hull and the core unnecessarily. What are realistic factors of safety necessary to build into a design - this is what it gets to. Deterministic designs are archaic and wasteful - there are better ways of ensuring the safety while getting the maximum life out of a hull.
If a bad combination of depth, water temperature and say the size of a turd in the crapper results in the limits of your hull/core evaluate how often those things are going to statistically occur at the same time and plan accordingly. If the likelihood of those three things stacking up are 0.0000000001% - it is wise to factor that in as a consideration of the design
It is a technique that is alive and well in the aircraft industry which can also have catastrophic and tragic events (military and civilian) the same as a boat. Probably time to start to incorporate some of this data into the design and life of our boats.
6/02/2011 5:19 AM
Being an old boat sailor, (616 class, 640 class 594 class) I can tell you that not only the hull gets tired, but the whole boat gets tired. Little things that really do not make much difference to the naked eye, really hose you when they go bad.
Sure, you just replace them, right? We were mixing and matching parts for the Gato (SSN615) with the last few remaining 594's just to get to sea - trading our broken part for another's good one. It just means they have the broken part to worry about. Sure, we got underway on time, but the Greenling was suckin' hind tit. We were the last 594 to decommission, and we got there on bailing wire and bubblegum.
And the Woody Woo was no better before she went in the yards.
The shaft seals leaked so bad on the Bolivar that we were discussing whether it was a controlled leak or flooding. We pumped bilges every half hour by the end of patrol, because the water was up to the deck plates in ERLL.
The cost to keep an old sub has got to come close to building a new one - a safe one. I can assure you I had my insurance policy in order when I went to sea on those boats.
6/02/2011 5:26 AM
A clarification on my words....
When I said to factor in the 0.0000000001% occurrence, I meant to take that unlikelihood of occurrence into occurrence, not to design specifically for something that will occur that infrequently.
6/02/2011 5:39 AM
Me thinks recently departed JO is a wee bit naive to the aspirations of the PLN and phoenix of Russia.
6/02/2011 6:40 AM
Has anyone thought about having Blue and Gold Crews on Fast Boats? This could keep the limited number of boats at sea longer (Works great for SSGN's) and would give overworked SSN crews a much needed break (right now a 14 month deployment cycle with a lot of boats doing 7 to 8 month deployments). We could keep more forward deployed to DGAR and Guam this way which would also conserve Reactor Plant hours.
6/02/2011 7:34 AM
My first boat was nearing 30 years old when I reported aboard. The boat was tired and worn out. We kept it going the best we could until decom, but it was a striggle. We had to get a hull cert extension in order to make it around to the yard, and then on our way there we ended up detouring from the arctic circle down through the Panama Canal and up to Bremerton based on materiel issues instead of transiting through the Bering Straight. This added more time to our transit and put us in a real time crunch to get there before our extneded hull cert exppired. To make it more fun we had a steam leak off baja that took us down to a single main engine. We got a week extension with only a little bit of time left before we would've had to surface off California and transit to Bremerton the hard way. Moral of te story, is that there is only so much time you can extend the life of a boat. At some point they are tired and ready to be put to pasture.
6/02/2011 8:29 AM
Were calculated hull life the only factor in determining maximum service, it would be a straight-forward engineering-informed risk decision. But a larger consideration is the intrinsic safety design of each class and that seems to always be left out of the discussion.
For example, we operated diesel boats to full design hull life (30 years) using the same engineering considerations as with nukes. But anyone with time in the pigboats and able to make comparison with the modern SSN will tell you that the old boats had a lot less going for them in backup systems and overall systems design than their later sisters. They were intrinsically less safe overall and those not SubSafe even worse off, something not entirely compensated for with depth restriction.
The submarine force has shied away from considering hull-life extensions because it greatly weakens the real-time argument to build boats. But reality is here and I think an entirely sound engineering-based and design-based risk calculation would permit significant hull-life extension of the current classes IF political considerations on how best to argue for new hulls were kept out.
That's what it boils down to: it's a political question, not an engineering one. Test-depth hull cycles are used as the primary life metric by some other submarine navies; some worthy combination of this with our conventional algorithm has merit, with class-safety considerations also brought in.
6/02/2011 9:08 AM
@Dardar - when were you in the 641?
When I was in 641 (86-89), right after a refueling overhaul out on first patrol, our shaft seals were making more fresh water than the still. She was tired, but in many, many ways, she was still a damn fine boat.
-Gerry
6/02/2011 10:55 AM
Gerry
I took her just up to the decomm in '94. She was still the best boat on the water, and we proved it by sinking the "Whatever CVN task group", including the L. Mendel Rivers, as we were a russian mega-sub. ("Mike" I think)
She was very tired, leaky and top speed didn't quite get to where it would when I first got there in '90, but she wouldn't quit.
On a side note; that was the only boat, that I was on, where both crews excelled and both crews thought that it was the best boat ever.
6/02/2011 12:09 PM
Typically, its not the deployments that hurt a boat, after all your only transitting from A to B then hanging out at B for a few weeks then transitting back to A. If your in the Gulf, just how deep can you go, na?
What ages a boat is the stress and BS the boat goes through back at home. Take ORSE for example. 4-6 weeks of underway drilling and spilling, cycling power and services, moving all the crap out of the Engine Room that "dosen't belong their" (yet every ORSE member 'knows' was their anyways). Vulcan Death Watches galore to get that "last" drill set in.
I wonder how much drilling and spilling and Field Day could be done inport in a fast cruise environment? Crew gets to go home and rest each night and anything that gets broken can be fixed by the IMA asap. Then go to sea the week before to shake out the underway bugs...leaving all the crap from the Engineroom on the pier.
CODT: How many weeks does a boat go to sea under "COs Discretionary Time" just do run a few drills and get qualls done? Sure, a boat needs to go to sea to keep the crew sharp and trained...but every week for 2 months strait?
And ya know what? That bit of ectra inprt time for the cew may be enough to make up for short cycled and extended deployments to help out with retention.
6/02/2011 1:01 PM
It costs a lot money to retrofit all that enlisted female crew quarters that is in the works for attack subs, and the money has to come from somewhere. One answer is to build fewer new subs and to stretch the lifespan of existing subs.
6/02/2011 1:46 PM
I agree with recently departed JO in that we can't have a discussion about whether fast attacks can meet minimum mission requirements unless we define what those are. If we are talking about the silly way we waste an inordinate amount of time in the workup cycle trying to do everything at once, resulting in a huge process inefficiency followed by deployments to places that may or may not be actually important to national security, then no, we can't meet operational tasking. For every boat that deploys to gain intelligence on a real-world developing threat that only a SSN can do, there is at least one, if not more, that does a deployment making 0-1 knots over ground at PD collecting SIGINT data that is questionably useful at best. Do you really need a 'fast attack' submarine to do that?
The reality of the matter is that the real need for SSN's has diminished greatly since the cold war, and the SSN force has fought a political war since the 90's to justify its existance. The future of the submarine force for the near future is the SSGN. It can perform littoral ops and deliver SEALs as well as an SSN, and deliver the payload of a CG while remaining stealthy. The SSN force only needs to exist to counter the blue-water submarine threat. Unfortunately there isn't much of that in 2011, and the Virginia class wasn't even designed for it.
The upside is that the reductions in the SSN force will at least force operational commanders to determine what's actually important and make big-picture process improvements that better utilize our ships and manpower. Maybe part of that is two crews to maximize at sea and training time, maybe part of it is not requiring a boat to do numerous in-and-outs for inspections inbetween major maintenance availabilities, and instead rolling those periods into distinct blocks to save on transit time. Only time will tell, but any fast attack sailor can tell you that there's very little room to squeeze man hours out of the fast attack schedule as it stands now.
6/02/2011 2:06 PM
6/02/2011 2:06 PM: spoken like someone who has been out of the game for a while...
6/02/2011 4:14 PM
6/02/11 411pm: Poor assumption. Also wrong.
6/02/2011 4:43 PM
We all know that some of these missions and the work-ups leading to them are BS. An example is keeping a boomer deployed for 3 months and only one week of actual alert time. What a complete waste of time...but I am sure it was justified by some knothead. And for the attack boats, I am sure you absolutely love those VIP, POMCERT/Workups with lots of CO discretionary time, and MIDN ops.
Not enough boats to support missions by 2030.....my ass! Just cut some of the BS deployments!
6/03/2011 10:48 AM
Funny, when I was a JO, I was told as many times that I could be told that my year group was small, and the number boats to command in 17 years would be very large. Command for everybody!
Now, my year group gets to command selection time, and there's no more boats than there were back then. FAIL.
6/03/2011 2:21 PM
I was at SubPac when the decision to extend the 688's was made. The entire discussion was about the hull. The core was a consideration, but in the end you just tell people they can operate less. But back to the hull.
Turns out when you design ships with slide rules you have quite a bit of extra margin when you later examine the as-built condition with fancy new computers. Based on this examination, it was decided (after much gnashing of teeth and hand wringing) that the hull life could be extended 10%. It was also made clear that additional extension was not feasible within safety margin.
So, Duck and others, it was about hull life and not core life. That said, if we magically extend the hull, the only way for the core to match will be to have our ships drive everywhere at 12knots and rarely get underway to train. That'll be greatly effective.
6/04/2011 4:23 AM
NHSparky, I hate to urinate on your parade, but avoiding the bad guys does not take speed and depth. Actually, those are typically the worst things to choose to avoid being found by the bad guys.
6/04/2011 4:24 AM
"There's a whole host of missions that occur in Litorial areas that do not require deep diving. I surmise a number of ships could be constrained by depth and still be very effective in these crucial mission areas. Same with various drug interdiction missions. Who cares how deep they go.
Tom"
A better question is "Is it really a good use of military hardware to use submarines for drug interdiction? I also am in agreement that people in the military tend to overblow the "Threat" from Russia and China, just as they did throughout the Cold War, but even ignoring those types of missions, there's lot of stuff of negligible importance, or that is better served by other platforms.
6/04/2011 8:30 AM
I also am in agreement that people in the military tend to overblow the "Threat" from Russia and China, just as they did throughout the Cold War . . .
Spoken without a clue. Are you Jimmy Carter?
6/04/2011 1:23 PM
Taiwan has two Guppy II's still operating. Ex-Tusk SS-426 and Ex-Cutlass SS-478. both are over 65 years old. Photo's of both boats in Taiwanese service are available at NavSource Online: submarine Photo Archive. Just google the names.
Turkey also operated Ex-Tang SS-563 and EX-Gudgeon SS-567 until 2003 and 2004. They were special mission boats in the Black Sea. Interesting comment from Turkish CO of Ex-Gudgeon re: question "What is the difference between US boats and new German boats Turkish Navy is buying?" Response was, "American submarines built for war, German submarines built for export."
Keep a zero bubble.........
DBFTMC(SS)USNRET
6/04/2011 2:59 PM
{Based on this examination, it was decided (after much gnashing of teeth and hand wringing) that the hull life could be extended 10%. It was also made clear that additional extension was not feasible within safety margin.}
Considering the advantages of modern computer modeling I'm surprised there isn't more than 10% margin available. Especially if you actually can model individual hulls using depth and time data, as well as transitions.
6/04/2011 5:42 PM
It's not just the hull and reactor. The seawater systems age regardless of the cycles on the hull or hours on the reactor. Extending the life of the hull based on less conservative calculations won't cause less erosion and corrosion in seawater systems. If we extend a hull life to meet future missions, we need to be prepared to spend the money on wholesale replacement of subsafe systems.
6/04/2011 6:14 PM
I hate to urinate on your parade, but avoiding the bad guys does not take speed and depth. Actually, those are typically the worst things to choose to avoid being found by the bad guys.
I would agree with that as well. I just used the two most glaring examples. Frankly, others have posted here as well as I can about that. But consider some of the other factors, such as noise signatures, which basically can't be changed once the boat is launched. You can TRY to make some equipment quieter, but we both know what the major noisemakers are on boats, and those don't get changed very often, if at all.
BTW--only boomer pukes hide.
6/05/2011 9:34 PM
Well, I know one thing, there are always pluses and minus for all the new safety tools and technology. This just seems to artificially line up the positive arguments for the risk perspective guys.
Don’t you listen to them, basically down the rat hole of risk analysis is some isolated guy in a languages that is indecipherable....it always ends up in a subjective judgment and interpretation of the underlying process or property. It is the most wildly speculative analysis I have ever seen ...it is the most wildly subjective analysis I have ever seen. It is the exact opposite of science...
Down the rat hole of this undecipherable technical language of risk analysis...you going a get a bunch of people picking and choosing the data they want to enter into the risk calculation for self interest...
Like in the old days, they only uses slide rulers, the assumption is they always widely over estimated safety in sub designes. I remember when they miscalculated emergency blow pressure and volume capabilities, the pressure air cylinder wouldn’t overcome max depth and flooding...guess what side got screwed.
I would frame the side rules boys as extremely skillful at the calculations they made....they built most of the nuke plants and submarines...and the rest of our world we live in today. For the whole with the tools they had at the time, these guy were extraordinarily smart and skillful with what they did. You remember our fathers and grandfathers, they put men on the moon with calculators and rudimentary computers...and weight and sitting on the cutting edge of a physical limitation was a big deal with getting these rockets off the ground.
You understand what I am saying, if you pick the happy side of the story that favors your self interest, you are going to sink your own sub...
If these guys aren’t totally up front with you with the pluses and minuses with all their safety tools, then you should shoot them on sight. If it is all positive information they are feeding you then they need to die (humor).
6/07/2011 1:31 PM
Alright, who left the loony bin door open?
6/07/2011 6:47 PM
@nhs, I never said hide...but when one is lurking one does not want to be found. The successful pickpocket is not one that hides, bur rather one that remains undetected and gets away with the loot. cue evil laugh
6/07/2011 6:54 PM
Alright Dammit!
Who the hell is on Mulligan watch? You cannot leave his cage door unsecured. You've gotta keep a steady bead on him at every turn or else, he causes disorder and a whole other clusterfuck of problems. Lead the little bastard back to his cage right now!!
Gentlemen, there is no excuse for this shit. Now fix it!
6/08/2011 12:30 AM
Wah, wah, wah...
6/08/2011 2:15 PM
Ummm...Yeah,
That's about the extent of you vocabulary isn't it Mulligan? Nice rebuttal there, you bombastic simpleton. Please stay away until you learn to formulate and express a complete thought without your meaningless discourse you enjoy douching the world with on a regular basis.
6/08/2011 4:10 PM
You gutless wonder, least I use my real name...
6/09/2011 7:05 AM
Gentlemen, rest your sphincters.
There is enough room to rant and rave, or agree with the status quo, or just spew verbage, for everyone. Any way it goes, it is all just opinions - and we know the cliché' about opinions.
Can't we all just get along? Who needs a hug?
6/09/2011 12:12 PM
Goodness, there is a lot of effective info in this post!
3/16/2012 4:44 AM
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