crush depth of Valiant class SSN's

[cc salvo]

Has it ever been calculated at what depth the  Valiant type SSN's would have reached before crushing ?
 On the same note how about the last P & O's ?

[oracle]

Whilst in Oracle in the afterends, we estimated the depth to be between 1150 and 1250 feet when the stern gland blew and we eventually recovered from negative buoyancy.
    It was Tot-Time too, so the main scare came from Tots slipping from the mess table. Quite a responsibility y'know.

[Sharkey]

What were you doing that deep?, we went to 700 I think it was, internal stuff bending away from the hull, lots of creaking, stopped every 100 feet check for leaks, very quiet throughout the boat. I heard someone ask(someone) do you believe in God, the reply was, at this moment, yes, but when I get home, no.

[Fingers]

I would hope there was a good difference between where the stern glands blew in and the actual crush depth.I'm sure there must be a published calculation somewhere but thankfully none of the boats mentioned ever put it to the test.

[Lofty]

The A class had an official max' depth of 600 ft ,but  seem to keep about 550 ft in practice --- they tested the two incomplete hulls in Devonport yard, to crush depth , can't recall now what happended. ACE and ACHATES

The bigger hull 'O' class were supposed to be as good as the much smaller 'A' and the draft requirments stated 650 ft max operating. High Yield advanced steel pressure hull.

The SSN had big diameter hulls, but no real idea what grade of steel was used and thickness of the plate or general construction  to compensate for this.

My 1980's book says VALIANT was built of High-Yield UKE steel for a diving depth of 1000 ft

The titanium Soviet ALFA was supposed to manage 3000 ft and  the US .
The Los Angeles class were a disappointment, both in max depth and speed .

The old USN Fleet boat CHOPPER was built for 350 ft and started to crush at 1150 ft before they managed to get up.I think she didn't go back to normal service.Plenty on the Web.

Lofty

[Lofty]

I realise I can give a most reliable operational depth .

From Admiral Galatin, USN, (ret)  in his book "SUBMARINE ADMIRAL"
He was a WW2 skipper and like other USN skippers was keen to see new boats built with the maximum operational depth.

He decided to join the brand new TANG , April 30th 1952 , to observe the first staged deep dive, finally reaching the maximum of 713 ft. The Admiral was very pleased and later boasted about at a mixed military conference, where an Air Force colonel responded -- I've flown deeper that that --pause-- over the surface of the Dead Sea ( 1292 ft below sea level).

This was a good submarine spoilt by  novel vertical engines that had to be replaced by extending the hull and fitting conventional engines.

The 'P' class was the British boat that like the TANG class was supposed to incorporate all the desirable features learnt from WWII and the general concepts of the German XXI ( not copies) , but for various reasons , not the least money , the long planned "P" class did not emerge until 1958 .

Plenty of good web sites about the TANG class giving dimensions that can be compared to the 'O' class. Here is just one http://navysite.de/ss/ss563.htm

About 1951 we were alongside the  new GROUPER ( TANG class ) and the old HARDER. Very impressive inside , large mess just for eating and large SS galley with two chefs (maybe three) very smart . A bit of a let down  going back to our rather seedy T boat.
Lofty 

[oracle]

What were you doing that deep?, we went to 700 I think it was, internal stuff bending away from the hull, lots of creaking,

We were at 600 ft. or so when the stern gland blew. Baby Subby OOW in the CR panicked, and his reaction put to motor room in a flap and they blew something (main motor field switches?) leaving us without propulsion. After pumping and blowing, recovered power and with a combination of all three, we drove up.

Not one drop of rum was lost.

[Lofty]

Browsing Admiral Galatin's book ( mentioned above) I came across a note about the earlier TANG ( SS306)  lost in WWII  http://www.fleetsubmarine.com/ss-306.html

She was a "Thick Skin " Fleet Boat  with an increase to 400 ft from earlier otherwise similar "Thin Skin" boats who had 300 ft .

She was taken down to 612 ft by her skipper following her official  post construction trials to 400 ft, November 1943.
=======================================================
I would note this may seem reckless of her skipper, but US boats had been taking their "Thin Skin " boats down to over 400ft to avoid Japanese depth charges on the assumption that there was a 100% safety factor.

WWII Pacific Senior Officer (S/Ms) turned a blind eye to the practice.

You can see how the new design policy developed post war , by these influential former skippers, included even greater operational depths.
Lofty.

[Pensioner]

Sorry Lofty but the 'A' Class deep dive boats when first built was 750 feet. How do I Know, it is the old story "been there, done that". I was given a pier head jump to the Amphion (the first A Boat) 14th September, 1946 to take it out to Hong Kong as part of the re-formed 4th Submarine Flotilla. Soon after our arrival We did a deep dive off HK. I was the Control Rum Messenger and kept the Log and recorded it all at every 100'. We had no problems whatsoever. The Captain was LCDR 'Paddy' Gowan, the 1st Lieut, LT.  John Coote and the Engineer Officer was Lt Rabbit. Probably over the years as the boats became older they reduced the deep dive depth 

[Lofty]

Pensioner , thanks for that , the figure I have is for the AMPHION, completed 27-3-45.
Official deep dive trials 12-4 -45 carried out east of Barm in the Sea of the Hebrides,  before official  hand -over to the Navy --600ft .
Carried out in stages --each time returning the PD then down again -- 400ft --500 ft ---600ft -- strain measurements were taken at 500 and 600 ft .

The dives were entirely satisfactory and a signal sent to the Admiralty , FOSM and Captain (SM) on surfacing . Full details of the test measurement methods  taken at 500 and 600 ft are given .The actual max' figure was 609 ft .

Interesting that 450 gallons needed to be pumped out at 600 ft to maintain trim.

The charts showed 100 -130 fathoms to sea bed.Intersting this was mentioned , but I suppose if they lost trim, this was the deepest they could go before hitting the bottom, not slide into oblivion!!

Now clearly once fully in RN hands and in commision, someone decided they could manage something deeper and tried 750 feet, just as was the case I mentioned earlier with the new USN submarine earlier in WWII.

The deepest trial depth I have ever been in an A boat was ARTEMIS to 525 ft.   It was simply a trial, nothing operational . But that would be three years after she was completed.

Generally speaking the submarine design experts consider it bad practice to take the boat any deeper than needed as it reduces the hull life, so again why, in the middle of a commission a need was felt to take ARTEMIS  525ft I don't know.
Why did Gowan take AMPHION to such an extreme  depth He reduced the hull life by the time I arrived on AMPHION in 1953, but there you are !!

But thanks for very valuable posting -- it expands the first hand   knowledge.
Cheers  Lofty

[Talent]

After the 1962 Amphion refit in Singapore Dockyard, the back end, from the engine room bulkhead, was air pressure tested. I can't remember the pressure now, pretty high, and the Engineer was a bit worried about the strain on the bulkhead. Then a few weeks later we went to 500 ft in the South China Sea, in 100ft steps. We had tied a taut string across the donkshop and it dipped alarmingly but we forgot about that when the port main motor cooling coil burst. Going down backwards with a stern down angle. Everyone was too excited to check the aft ends depth guage. Also, one of the sailors had fixed his brand new Rolex Submariner in the fin and when we surfaced it was full of water.
Oh happy days....

[Lofty]

Talent, I am surprised the ER circulating water system hull valves weren't closed. That is a lot of pressure on that fairly complicatedER/  CW system and in particular the cupro- nickel tubes  cooling the  air blast cooling air flow,  were surely not designed for this pressure?

The bulkheads were supposed to be good for the flooding of the escape compartment being flooded to about 250 ft, max' anybody could expect to survive a twill trunk escape.
Lofty

[Pensioner]

Sorry Lofty but being a lowly Able Seaman, submarine Detector Radar I am afraid the LCDR Gowan didn't take me into his confidence of why we were at depth. All I know is that I was the Contol room Messenger and faithfully recorded every word that the three Officer's uttered on  that day. I can't recall any pumping or flooding instructions of which I am sure there were many, especially the for'rd and after Trim main line suctions

[Lofty]

Thanks Pensioner , I must assure you that I was not casting any doubts whatsoever on your quite clear observations --just wondering why they did it.

Of course the RN was looking into the design of the new PORPOISE class and perhaps wanted information?

Never mind your reliable report is of great historical value at time when the deep diving of submarines  was getting to be more and more important and this increased as the Cold War progessed.

Keep well
Lofty