Royal Navy Aircraft carrier breaks down again.

[TheGreenAnger]

Thanks 4m - that puts a new perspective on it!

If they sailed with the starboard shaft just trailing but no lube then they may have engaged it when clear of the coast, leading to an already overheated gland heating up more and the shaft sustaining damage. If they had it locked until offshore then engaged it with no lube then same result a little later. Desperation on getting to the prestigious exercises in the States and taking a chance on it coming good, which led to big red faces. Who authorised that sailing and who knew what and what advice was given - watch the press, but I notice the furore of interest has died down in the papers - at whose request I wonder?

From the link posted here.

It may be unrelated but the wake visible in the photo above, taken as she sailed yesterday, appears to indicate only the port shaft turning.

They had problems from the off. I suspect FD2's suspicions are well founded!

[FD2]

The problem may have occurred after slipping and manoeuvring to leave the harbour and it was easier to proceed on one shaft than to try and get back alongside. Whatever, it's not a seaworthy ship at present. It's easy to speculate too much so I'll shut up - maybe an explanation will be forthcoming!

[G-CPTN]

They should have had an 'Engineer' (like on an aircraft).

[FD2]

Interesting link to the heart of the problem, perhaps! https://gcaptain.com/control-50000-shaft-horsepower/

[TheGreenAnger]

Interesting link to the heart of the problem, perhaps! https://gcaptain.com/control-50000-shaft-horsepower/

Interesting reading FD2. It is hard to believe that these bearings would not have had bearing sensors designed to monitor the temperature, usually using thermocouples. I would also be surprised if these bearings didn't include vibration sensors. Any anomalous reading should have been monitored on the master control panel.

It is not credible that any gross technical failure such as loss of lubricant could have gone unnoticed. It thus leaves us sucking air and maybe we will have to wait for the official report, redacted and obfuscated as it is likely to be, all ostensibly on the grounds of national security, but more likely to spare the blushes of those senior officers, mandarins, and maybe even politicians above them.

We may have to wait a long time!

[FD2]

Agree! Not believable they wouldn't be fitted with those sensors.

[Fox3WheresMyBanana]

Speculation: Aircraft engine vibration (and other) sensors can be quite unreliable, especially in the early stages of the engine's life. Maybe the same here. Perhaps the technicians had got into the habit of ignoring false warnings which then turned out to be genuine.

[Boac]

Dry dock it will be - MOD.

[TheGreenAnger]

A good simple summation of the status quo.

https://www.forces.net/technology/sea-v ... -secretary

[Fox3WheresMyBanana]

Thanks TGA.
Followed the links in that article, and the UKDJ is reporting that the prop hit something on the seabed, which has likely bent the shaft.

Multiple independent sources have told me that it is believed that the warship’s propellor hit something on the sea bed.
“Either the propellor hit the floor or something on it. Definitely dry docking needed, and Amsterdam is being touted as an easier option than Rosyth.”

That sounds a lot more likely than a major cock-up with the shaft lubrication to me. The clearances are very small in the Solent, so something like a sunken container in the deep channel could have done it, which would not be the fault of the Andrew.
https://ukdefencejournal.org.uk/british ... r-repairs/

[TheGreenAnger]

Thanks TGA.
Followed the links in that article, and the UKDJ is reporting that the prop hit something on the seabed, which has likely bent the shaft.

Multiple independent sources have told me that it is believed that the warship’s propellor hit something on the sea bed.
“Either the propellor hit the floor or something on it. Definitely dry docking needed, and Amsterdam is being touted as an easier option than Rosyth.”

That sounds a lot more likely than a major cock-up with the shaft lubrication to me. The clearances are very small in the Solent, so something like a sunken container in the deep channel could have done it, which would not be the fault of the Andrew.
https://ukdefencejournal.org.uk/british ... r-repairs/

+1

[FD2]

There was a major dredging operation to deepen Portsmouth Harbour for the two new carriers. I believe it uncovered many old items of interest from hundreds of years of use. I'm keeping my fingers crossed that was the cause. I think it would have been noticed when it happened and propeller damage must have backed that explanation up.

[Boac]

The pic showing only the port screw working begs the question that IF she had struck one of Davy Jones' chests on the way out of harbour it would surely have been noticed? and the only logical thing to do must be to hang around near the garage and not push off down to the south-east of the IoW and thrash the beastie?

I do smell a very large rat here, especially with the unexplained '24 hr tech delay' on sailing. Get that gang-plank ready.....

I have the honour to remain, Sir, your distrustful servant.......

[PHXPhlyer]

At 65,000 tons, I don't think it would be quite like hitting a pothole.

PP

[Boac]

..............mind you, the TGA Youtube, showing an earlier return to anchorage, also shows only the port screw in use, so maybe that's a 'matelot' thing about driving PoW around with tugs?

[FD2]

At 65,000 tons, I don't think it would be quite like hitting a pothole.

PP

Any distortion of the propeller would cause noticeable vibration. Certainly noticeable to an array of detectors that I hope would be fitted.

As Boac has mentioned it might be standard procedure to just use one propeller as two, even at slowest revolutions, might just move the ship so fast that it might be too difficult to stop it from running aground in the event of, say, a rudder problem. If they did strike the bottom or hit a submerged obstruction it should be discoverable from a survey of that part of the harbour they had moved over and the track followed on the way to sea. Only if any damage to the ship indicated that as a reason.

Despite its size the whole propulsion system is finely balanced system. In days of yore the shafts were very slowly turned over every few hours when alongside to make sure that no hogging or sagging had occurred in the propeller shafts between the plummer blocks.

Anyway maybe we'll find out for sure idc.

[Boac]

QE to replace on US trip. She is in the Birkenhead area at present. (Check couplings.... )

[FD2]

When the Royal Yacht was being placed alongside the Ocean Terminal in Leith, as a tourist attraction in her retirement, the two extremely valuable phosphor bronze propellers were removed and were sitting on the jetty. A lorry turned up and loaded them, with the assistance of a gullible crane driver, and was just about to depart when a security guard decided to check the driver's credentials and authorisation. The propellers now sit inside the Ocean Terminal as an indoor tourist attraction!

I wonder what might get 'misplaced' if PoW were to go into Cammell Laird's dry dock.

[TheGreenAnger]

At 65,000 tons, I don't think it would be quite like hitting a pothole.

PP

Any distortion of the propeller would cause noticeable vibration. Certainly noticeable to an array of detectors that I hope would be fitted.

Despite its size the whole propulsion system is finely balanced system. In days of yore the shafts were very slowly turned over every few hours when alongside to make sure that no hogging or sagging had occurred in the propeller shafts between the plummer blocks.

Forgive the slight rant and while not Royal Navy or topic specific, this comment is still apposite to sagging shafts, as this is precisely what happened to the shaft linking the turbines in the old back up power station in Cape Town after the "new dispensation" took over at the electricity supply commission (ESKOM) in the 1990's when they decided to mothball the gas fueled power plant while neglecting to keep up preventative maintenance, by not running the shaft up to the required RPM every week, "why bother as nothing can go wrong, when we have a nuclear power plant at Koeberg" and "they never go wrong do they?". Well come the day some idiot dropped a bolt into the main turbine rotor at the nuclear power plant which wrecked the turbine thereby necessitating a plant shut down while a new turbine was shipped by sea from France, and they attempted to run up the mothballed gas plant only to find that the shaft had been irredeemably bent due to gravitational sagging! The plant had effectively been wrecked by doing nothing!

[TheGreenAnger]

QE to replace on US trip. She is in the Birkenhead area at present. (Check couplings.... )

Broken coupling

The reason HMS Prince of Wales could not begin her planned deployment is that an external SKF coupling that connects the outer propellor shaft to the drive shaft from the propulsion motors failed. This is a rare event and a situation described by the First Sea Lord as “unprecedented” as few marine engineers can remember an instance of this happening. Random unpredictable failures are uncommon but can still occur even if equipment is well designed, maintained and operated.

However, unconfirmed sources suggest HMS Prince of Wales was already experiencing some significant problems with her starboard motors and under pressure to sail, required special permission to leave on Saturday with a known defect. Her sailing had already been delayed by 24 hours and she put to sea with civilian staff from the original equipment manufacturer (GE Power Conversion) onboard, presumably confident the motor could be repaired while underway. She sailed using only the port shaft and her propellors did not strike the sea bed as has been rumoured. Press reports that the breakdown was caused because RN engineers “forgot to grease the shaft” are contemptible nonsense. (The external bearings are sea water-lubricated for starters).

Subsequent updates suggest the motors were in fact working correctly and their strange behaviour was the result of the coupling failure. Admiral Moorhouse has also confirmed there is “significant damage to the shaft and propeller and some superficial damage to the rudder”.

Repair in Rosyth
The ship will return to Portsmouth in the next couple of days to offload some stores and a temporary fix will have to be applied to lock the faulty shaft to prevent damage while she on her way to dry dock. Tidal windows that allow the carriers to pass under the Forth Bridges and over the dock sill are only available every few weeks but Rosyth will be the destination. Despite rumours she might use dry docks in Amsterdam to save time, Rosyth was always by far the most likely option for the repair. Babcock has a contract to keep the facility ready for unplanned dry docking of the carriers at their secure site with personnel already experienced working on the ships. This will not be a quick fix and expect PWLS be out of action for some time. It is possible her 5-yearly Lloyds Naval Ship Rules hull inspection which was due next year anyway will be brought forward and combined with the repair work, allowing more availability for her in future.

https://www.navylookout.com/hms-prince- ... r-tasking/