Friday, January 5, 2018

UK Navy Aircraft Carrier Story is Frankly Puzzling

The British Navy recently launched a new aircraft carrier, the HMS Queen Elizabeth.  As is the usual routine, the ship is undergoing a period of sea trials to evaluate how well everything performs.  A couple of weeks ago, the story broke to much fanfare that the ship was leaking and might have to go to dry dock for repairs.

The part I find puzzling?  A big deal is being made over this:
A faulty seal around one of the vast warship’s propeller shafts means 200 litres of sea water pour in every hour.
200 litres per hour?  In Imperial units, that's just shy of 53 gallons per hour.  Granted that nobody wants to be on a ship that's taking on tons of water, but for a ship that displaces 77,800 short tons, 53 gallons, 442 pounds, just isn't much of a leak. 

As a reference to those of you who aren't boaters, here's a low cost bilge pump I've had on a fishing boat before.  For a mere $70, one can buy a bilge pump that will pump out 750 gallons per hour, 14 times as much as is leaking into the carrier.  I know a MilSpec version of that plastic pump will cost at least five times that, but they could still deploy dozens of those on the ship.  And guess what?  Ships that size have pumps.  A little shopping at a Marine Supplies store like West Marine or Overton's will show you bilge pumps for the recreational boater that vastly exceed the capabilities of that little Rule 750 GPH pump and vastly exceed the amount of water leaking in.

If my boat was taking on 53 gallons per hour, I'd run the pump for 4-1/2 minutes every hour and keep an eye on it to make sure it's not getting worse.  

(HMS Queen Elizabeth, heading for her home port of Portsmouth)

So why the kerfuffle?  That's my puzzle.  First off, the purpose of sea trials is specifically to find issues like this.  None of the companies who built the "largest warship in UK history" are contesting that they're at fault.  The Sun reports:
An insider added: “We’re about to uncover the true cost of carrier ­operations.

"There is a feeling that the ACA mugged us off by not sorting this before the handover.” 

The Queen Elizabeth is currently in Portsmouth and may need to go back into dry dock to be fixed.   [Note: the ACA is the Aircraft Carrier Alliance, a grouping of BAE Systems, Babcock and Thales, who built the ship - SiG]
The BBC has what seems like a bit less sensational summary.
The truth is similar leaks in other warships are not unusual and can be fixed relatively easily.

The difference this time though is the scale of HMS Queen Elizabeth and the fact it has just been handed over to the navy.

The big question is whether the leak can be fixed while it is still in the water.

The navy insists the job can be done without her going back to dry dock, which would be costly and add to delays.

Either way, the navy insists the fault will have to be rectified and paid for by the contractors, along with a list of other "snags".
I just don't see what the big deal is.  While I don't claim Naval experience, I think if you buy a multi-billion pound aircraft carrier and this is all that's wrong, you've done pretty damned well.  Perhaps it's some sort of UK politics, which I have to admit is rather opaque to me.  Perhaps someone from the UK might comment if I've missed things. 


  1. One of the USA LCS mini-ships had a leaky main, the problem wasn't that some seawater got in, the problem was what and where it got into. I would think that with these being warships that have a higher chance than regular merchant ships to have damage or impact in this area, it would be hardened against ingress. The LCS lost an engine to a leak though...

  2. Six years in the US Navy in the Engineering department here.

    The shaft seal is supposed to leak a little, because the water leaking in is used as both a lubricant and as coolant for the seal. he water which intentionally leaks in ends up in the bilge in the shaft tunnel and, after processing to eliminate any oil or other pollutants, is pumped overboard.

    If the seal is leaking too much, it can be tightened, and if that fails, then it can be replaced without the entire ship going in to dry dock. The seal, like all seals, is after all a consumable item.
    The latest seals use a form of water-lubricated ceramic/composite bearing with a face sealing arrangement. In the event of a catastrophic failure of the seal, an inflatable balloon can be pumped up to seal the shaft and avoid water ingress. The shaft probably cannot be turned in this case, so not so useful if you only have one shaft… The QE has two.

  3. You are perfectly correct, this is the usual politically inspired cock wafflery and breathless handwringing by know nothings in media. It's a minor leak, the contractors will fix it under the terms and conditions, but the contract was unpopular with the opposition party and their brain dead supporters so much is being made of it.

    1. Now this makes sense. I noticed how they said, “now we’re going to find out what carrier operations really cost”, which sounds like political griping that they were sold a bad idea.

      It’s like our Evil Party sniping at any DOD program that doesn’t pass everything the first time.

  4. There may be other problems (classified under the Official Secrets Act) and they're blaming propellor shaft seal leaks. I agree with Divemedic (above). I went on HMS Q E last summer when I was in town courtesy of old friends (see my blog). In my youth as a serving US officer, I was seconded to the Royal Navy for two years and then two years to the Special Air Service. Youngsters then are admirals now so it's not because I'm cool. I just have friends from the glory days. One problem that the Brits have is training crews for this and the follow-on carrier, and that is not a small problem. USN is supporting their training efforts both for their new air wing (mixed RN and RAF aviators/pilots) and the ship's crew.

  5. Of course, there's always the possibility that the Media reporting this got their units mixed up, and it's not 200 liters per hour but is instead 200 liters per second. Never forget that the Triumph motorcycle was a product of British engineering...

    1. Not just the Triumph motorcycles, but also Nortons and BSAs, etc. Plus anything automotive which used any parts made by Lucas Electric - Jaguars, MGs, Triumphs, etc. I've had friends whose Jags sat in the shop (here in America) for months waiting on a Lucas parts. Since Lucas produced the lighting systems on a lot of British motors, Joe Lucas was known as "The Prince of Darkness". A lot of ignition systems/parts were made by Lucas as well as some aviation and aerospace parts. (Glad I never had to go up in a British-made aircraft.)

      I once had to wait for a new hydraulic dampener (what passes for a shock absorber on an MG) for my MGB for about four weeks, until I finally went looking for - and found - a used one in good condition, which I bought instead. I didn't own that car for very long.

  6. Yes the opposition party has been kicking up a storm for years on these "thefts from the social programs for warmongering monuments". This is just Democrat/Republican posturing in the international press. Question day was really interesting when this was brought up before. According to the Labour MPs, the government was kicking out orphans and old people and taking their food off their tables to pay for the RN.

  7. There are other problems that they don't want to talk about. A ship like this is incredibly complex made more so by government and political demands. It is impossible to build them "perfectly" and there are always problems and in very large very complex systems problems are very large and very expensive. If the government and builders were totally honest and listed all the problems it would be grist for the mill for the anti-military spenders who would prefer to use those funds to buy the vote of poor and degenerate citizens.

    I might add that today an aircraft carrier is the biggest and most expensive target in the world. In the first 24 hours of a real war the enemy will destroy or disable every aircraft carrier (there aren't that many and I know where half of them are at any moment and with a hour of research I can tell you where the rest of them are). That is not to say we shouldn't have them but more to say we need to recognize that in the last 10 years or so they have become much more vulnerable and we cannot use them and expose them the way we did years ago.

  8. I had read on a military web site that prop shaft bearing seals are one place you can expect to have leaks. Divemedic filled in the interesting details.

    1. Yeah, during an exam by the boat surveyor who was checking out the used catamaran we had made an offer on, our port hull started taking on water. Nothing the bilge pump couldn't handle, but more than a trickle. When we completed our sea trial and he wrote up the boat's deficiencies, he admitted that he couldn't determine why we had a leak in that hull, since it didn't leak while we were at rest.

      About a week later, when we hired a marine engineer to make some repairs, he discovered the packless shaft seal on the port side was completely loose. The forward end of the seal was tight, but the aft part was completely loose. When the shaft spun while underway, several gallons a minute came aboard through the hull opening the shaft passed through. When we stopped (or we shut it down to sail), the aft part of the shaft seal settled back against the opening, and the water stopped flowing.

      Needless to say - but I'll say it anyway - this surveyor whom our broker raved about was an incompetent ass. He missed several serious issues, but wrote up a bunch of things that he said didn't function - because he didn't know how to operate them. Like the stereo sound system %-)

  9. A lot of this is the anti-western coalition in the house of commons. The pacifist see the world rearming for the first time since the 1930's and they have there "nickers in a twist". Russia is laying down carrier hulls as is China, Japan and America. There nightmare is the "battleship race" that led up to both world wars, and they don't want Britton in it.---Ray