battlecruiser HMS Tiger survives til Second World War?

[Owens Z]

Battlecruiser HMS Tiger, commissioned in 1914, was scrapped in 1932 after distinguished service to the Royal Navy. What if she hadn't been scrapped, and (being by all accounts in good shape) survived five more years, when the looming threat from Japan, Italy, and Germany was becoming obvious? Perhaps to comply with the London Naval Treaty she was demilitarized in 1932 rather than scrapped, like the Hiei of similar design; or a tired R-class battleship was scrapped in her place; or she simply languished rusting in some backwater. (No aspersion is cast here on Britain's compliance with signed arms limitation treaties, which was much stricter than that of most signatories).

Using our knowledge of the times and the technologies, and, yes, the benefit of hindsight, what would be the optimum course to get Tiger into shape to fight in the coming war, if you agree with me that the big ship would be useful? I suggest to you that a middle course would have been wisest, between the barest minimum (scrape the barnacles, slap on a new coat of paint, enlist a few hundred coal stokers, and sail to war to do her best) and the extreme and expensive reconstructions of the Kongo class and the Andrea Dorias, which among many other things lengthened and re-formed the entire hulls. I will call my refitted warship HMS Tiger bis, for clarity. Tiger bis would be about two years off her feet (say, mid-1937 to mid-1939) and would have the following work done:

· strip out the original direct-drive steam turbines, coal-fired boilers, and coal bunkers, and replace with modern geared steam turbines, new lower-rpm propellers, and oil-fired boilers

· entirely delete the underwater torpedo tubes and torpedo magazines

· replace the dated 13.5-inch guns (1410 lb Greenboy shells) with eight 14-inch Mark VII guns (1590 lb shells) as used on the new King George V battleships, and substantially increase the max elevation from 20°

· add modest bulges to the sides, to better resist torpedo hits

· drizzle anti-aircraft cannon around the weather deck, and [later] increase their number and update the weapons as the Second World War progresses, like all other capital ships did

· update communications, and [later] add radars and electronic warfare gear as those become available


Although they were out of production, Britain had some stores of 13.5 shells and guns left in the late 1930's, but I still think a firepower upgrade is indicated. Weight of metal on the enemy from Tiger bis's broadside is usefully more than the Renown class's 11,628 lbs (and also more than the Scharnhorsts, updated Kongos, etc.). No doubt during the refit, judicious additions of deck armor would be done, complementing the additions done post-Jutland, but I don't want Tiger bis to be heavier than, say, 4% above her 1918 full-load displacement, both for reasons of economy and also to avoid the serious weight problems of, for example, the Queen Elizabeth class and HMS Vanguard (as I said, hindsight is allowed). Some 6-inch casemate guns can be taken off as needed to help with this weight goal. There were no aircraft aboard after the two flying-off platforms for Sopwiths had been discarded, but I affirm Tiger bis has no aircraft handling capability. The ship is faster than her 29-knot maximum when new. Tiger bis is more robust and hit-tolerant than the flimsy Renowns (which nonetheless fought valiantly).

What do you all think of my suggested refit? Please weigh in. I believe this ship would have been worthwhile for many roles in WW2 against Japan, Italy, and Germany. I don't know whether Tiger bis would have survived the savage fighting (and speculation on that is welcome), but if she did, she would today be a proud museum ship in Portsmouth to visit, the last of the Splendid Cats, with funky red, white, and blue artwork on her hull inspired by the dazzle painting of yesteryear.

 

[EwenS]

I think the Admiralty's view of Tiger was best summed up by Friedman:-

"Although the battlecruiser Tiger and the four Iron Dukes survived the Washington Treaty .....virtually nothing was invested in them. Tiger became a gunnery test and training ship. What money was spent went into the ships with lasting value, the 15in battlecruisers and battleships."

Like Hiei (or Hiyie as spelt in the Treaty) Iron Duke survived the 1930 London Treaty by virtue of Article II(1)(b). The only way Tiger survives is as a stand in for Iron Duke.

"These ships shall be reduced to the condition prescribed in Section V of Annex II to Part II of the present Treaty. The work of reducing these vessels to the required condition shall begin, in the case of the United States and the United Kingdom within twelve months, and in the case of Japan within eighteen months from the coming into force of the present Treaty; the work shall be completed within six months of the expiration of the abovementioned periods."

Section V​

Vessels retained for training purposes​

(a) In addition to the rights already possessed by any High Contracting Party under the Washington Treaty, each High Contracting Party is permitted to retain for training purposes exclusively the following vessels:​

........United Kingdom: 1 capital ship ("Iron Duke");
​

(b) Vessels retained for training purposes under the provisions of paragraph (a) shall, within six months of the date on which they are required to be disposed of, be dealt with as follows:

1. Capital ships​

The following is to be carried out:​

(1) Removal of main armament guns, revolving parts of all barbettes and turrets; machinery for operating turrets; but three turrets with their armament may be retained in each ship;​

(2) Removal of all ammunition and explosives in excess of the quantity required for target practice training for the guns remaining on board;​

(3) Removal of conning tower and the side armour belt between the foremost and aftermost barbettes;​

(4) Removal or mutilation of all torpedo tubes;​

(5) Removal or mutilation on board of all boilers in excess of the number required for a maximum speed of eighteen knots.

​

Iron Duke's forward boilers were mutilated and the remainder converted to oil firing.

From Burt "British Battleships 1919 - 1945" in March 1939 the possibility of restoring her to active service was examined. 11in main belt to be added. Missing 13.5in turrets and guns put back aboard (the were in storage at Rosyth). New secondary armament of 4-8 4.5" or 5.25" mounts. He goes on:-

"The main argument against the project was the question of speed: the entire boiler/engine/machinery arrangements would have to bbe renewed to achieve the desired increase, with outside estimates ranging from £920,000 to £1,200,000, which could be better spent on a new ship, it is not surprising that the idea was dropped."

The same issues would have been met with your proposed modernisation of Tiger.

As for your idea of replacing the main armament in Tiger with 14" Mk.VII from the KGV, unfortunately it is not that simple. Each turret is designed for a specific weapon. It sits on an armoured barbette designed to absorb the forces generated on firing. That barbette is engineered into the ship around it. Put a new gun in and you need to look at re-engineering the whole ship from top to bottom.

The 14" gun as a calibre wasn't selected for the new battleships until late 1935. The guns then had to be designed & built along with their new turrets. They were only ready for installation in KGV herself in 1939/40.

Then there is the issue of whether industry could produce the new guns / turrets / armour necessary on top of what was already needed for the other reconstructions and new construction. These industries were run down inter war due to a lack of orders and it took time to get them back up and running. They were limiting factors in battleship production and reconstruction.

When it came to the Italian ships, their bow sections simply had a new structure built outside the original structure. Their existing 12"/46 (305mm) guns were remanufactured as 320mm/44 and fitted to the same turrets with the guns generating a modest 13% increase in muzzle energy. The increase in the forces involved in going from the 13.5" of Tiger to the 14" of the KGV would, I believe, have been far greater.

So while Tiger might appear useful in WW2, she was essentially a 30 year old pre-Jutland design, requiring a huge, for the time, amount of money spent to reactivate her that would still have produced a mediocre ship useful for little more than convoy escort.

 

[CV12Hornet]

And financially such a comprehensive rebuild would require the Brits to substitute her for one of the ships that did get a reconstruction IOTL - there just isn't the money available for more, and the Brits declined rebuilding Barham and Repulse to Warspite standards anyway.

I doubt even this rebuilt Tiger would be worth giving up a reconstruction of Queen Elizabeth, Valiant, or Renown.

 

[Rule of cool]

Britain could do a lot of rebuilding of more valuable ships before rebuilding Tiger was reached on the priority list.

 

[BlackBat242]

My first thought was: "get her functional, then put Hood in drydock for her planned modernization".

My second thought was "or get her functional, then put Repulse in drydock to bring her up to Renown's fit".

 

[BlackBat242]

Iron Duke's forward boilers were mutilated and the remainder converted to oil firing.

From Burt "British Battleships 1919 - 1945" in March 1939 the possibility of restoring her to active service was examined. 11in main belt to be added. Missing 13.5in turrets and guns put back aboard (the were in storage at Rosyth). New secondary armament of 4-8 4.5" or 5.25" mounts. He goes on:-

"The main argument against the project was the question of speed: the entire boiler/engine/machinery arrangements would have to bbe renewed to achieve the desired increase, with outside estimates ranging from £920,000 to £1,200,000, which could be better spent on a new ship, it is not surprising that the idea was dropped."

The same issues would have been met with your proposed modernisation of Tiger.

Hardly... Iron Duke's original top speed was 21.25 knots... her hull was designed for that and slower - to increase her speed more than maybe a knot or so would require hull lengthening and reshaping similar to that applied to the Italian and Japanese rebuilds.

Tiger's original speed was 28 knots... no hull changes would be required to maintain that speed through the modernization - and maybe reach 30 if available SHP is boosted.

As for the guns... the 14" twin turret on the KGVs (1939) required a barbette inner diameter of 29' 6" - while the 13.5" twin turrets all had a barbette inner diameter of 28'.

That, along with the differences with the gun mounts etc, means that they would have to keep their 13.5" guns and turrets (suitably modified for greater elevation). The turrets that were removed from Centurion & Iron Duke historically were kept, so if Tiger had been training ship her removed turret would be easily replaced.

Even so, I still think that the UK would be better off using her to enable either of the unmodernized 15" battlecruisers to be modernized. Hood would likely survive her encounter with Bismarck with improved armor, but Repulse would still fall victim to the IJN torpedo bombers in my opinion, so unless Tiger is sent to Singapore instead of Repulse, then Hood should be the one modernized.

 

[EwenS]

Burt doesn't say what the speed required from a refitted Iron Duke was, and makes no mention of hull reshaping. But the need to add bulges would have meant an increase in power just to get her back to 21 knots without massive hull changes.

But Tiger, stripped as a gunnery training ship as set out in the 1930 London Treaty (see above - that would have limited her to 18 knots just like Iron Duke meaning removal / mutilation of far more boilers than lD lost. She would also have had to be bulged resulting in a loss of speed. So greater cost to restore her original 28 knots), through the 1930s is useless without spending money on modernisation, which was better spent elsewhere.

With everything going on and with its worldwide commitments the Admiralty felt it couldn't have any more than 3 capital ships (of the 15 it then had) out of service for reconstruction at a time from the mid-1930s

1933-37 "large repairs" to Repulse, Malaya & Warspite. When they opened up Warspite they found her machinery needed replaced which extended the refit time and allowed some of the changes planned for the next group to be incorporated. So she became a kind of half way house between Repulse & Malaya on the one hand and the next 3 on the other.

These were too early for modernised secondary armament of 4.5" or 5.25" DP guns (1935 designs).

Royal Oak was also worked on in this period before it was decided to concentrate on the faster ships.

1936-1940 Renown, QE & Valiant.

Then from 1940 Nelson, Rodney & Hood. But war stopped that. Had Hood survived, something would have had to be done in 1942 as her machinery needed a total overhaul.

Each round was 1 battlecruiser & 2 battleships. Hood, being the most modern of the 3 battlecruisers was always going to be the last to be reconstructed.

The idea in 1930 of keeping a 13.5" armed battlecruiser designed pre-WW1 and sacrificing a 15" R class battleship in place of ID is plainly absurd.

Edit:- Barham had been the last QE to go through the previous round of modernisation, being in dock 1/31-1/34).

Nelson & Rodney were a priority over Hood due to their 16" main armament needed to challenge the Nagatos.

 

[Dilandu]

What about of simply drilling 343-mm barrels to 356-mm size? Of course, it would still require turret modernization (breech and loading systems), but could be done much easier than complete turret reconstruction).

 

[EwenS]

What about of simply drilling 343-mm barrels to 356-mm size? Of course, it would still require turret modernization (breech and loading systems), but could be done much easier than complete turret reconstruction).

Not that simple.

These big guns were of "built up construction" with a number of tubes fitted one inside the other.

Built-up gun - Wikipedia

en.m.wikipedia.org

There are photos here of 13.5" under construction at the bottom of this page

United Kingdom / Britain 13.5"/45 (34.3 cm) Mark V - NavWeaps

navweaps.com

While the Italians took the 305mm guns and converted them to 320mm there was a lot more involved than simply "drilling" out the bore. The description given on Navweaps is

"The conversion consisted of boring out to remove the original A tube and apparently some of the wire. The remainder was shrunk on to a new A tube. It is possible that a shrunk or tupped inner A tube was also fitted."

This work could only be carried out in a handful of factories in the UK in the 1930s (there were only 3 involved in manufacturing the 78, including spares, 14" Mk.VII for the KGVs). As can be seen from the photos, it involved seriously large chunks of steel, huge machinery and a lot of heat. There is a photo in this article of the "Cathedral" at Beardmore's Parkhead Forge Works in Glasgow, where many of these guns were manufactured.

History Timeline of the Parkhead Forge, Glasgow

‘Transport is the Thing’ – Sir William Beardmore By Evelyn McKechnie I grew up in Parkhead, and the Forge was the main employer for the East End of Glasgow and beyond. My father w…

spotonlocations.wordpress.com

Those factories were also responsible for relining the 15" & 16" guns as the liners were worn away through routine use.

So again the question is where is the spare capacity for the design of your proposed conversion let alone the manufacturing capacity.

 

[tallguy]

I think the Admiralty's view of Tiger was best summed up by Friedman:-

"Although the battlecruiser Tiger and the four Iron Dukes survived the Washington Treaty .....virtually nothing was invested in them. Tiger became a gunnery test and training ship. What money was spent went into the ships with lasting value, the 15in battlecruisers and battleships."

Like Hiei (or Hiyie as spelt in the Treaty) Iron Duke survived the 1930 London Treaty by virtue of Article II(1)(b). The only way Tiger survives is as a stand in for Iron Duke.

"These ships shall be reduced to the condition prescribed in Section V of Annex II to Part II of the present Treaty. The work of reducing these vessels to the required condition shall begin, in the case of the United States and the United Kingdom within twelve months, and in the case of Japan within eighteen months from the coming into force of the present Treaty; the work shall be completed within six months of the expiration of the abovementioned periods."

Section V​

Vessels retained for training purposes​

(a) In addition to the rights already possessed by any High Contracting Party under the Washington Treaty, each High Contracting Party is permitted to retain for training purposes exclusively the following vessels:​

........United Kingdom: 1 capital ship ("Iron Duke");
​

(b) Vessels retained for training purposes under the provisions of paragraph (a) shall, within six months of the date on which they are required to be disposed of, be dealt with as follows:



Iron Duke's forward boilers were mutilated and the remainder converted to oil firing.

From Burt "British Battleships 1919 - 1945" in March 1939 the possibility of restoring her to active service was examined. 11in main belt to be added. Missing 13.5in turrets and guns put back aboard (the were in storage at Rosyth). New secondary armament of 4-8 4.5" or 5.25" mounts. He goes on:-

"The main argument against the project was the question of speed: the entire boiler/engine/machinery arrangements would have to bbe renewed to achieve the desired increase, with outside estimates ranging from £920,000 to £1,200,000, which could be better spent on a new ship, it is not surprising that the idea was dropped."

The same issues would have been met with your proposed modernisation of Tiger.

As for your idea of replacing the main armament in Tiger with 14" Mk.VII from the KGV, unfortunately it is not that simple. Each turret is designed for a specific weapon. It sits on an armoured barbette designed to absorb the forces generated on firing. That barbette is engineered into the ship around it. Put a new gun in and you need to look at re-engineering the whole ship from top to bottom.

The 14" gun as a calibre wasn't selected for the new battleships until late 1935. The guns then had to be designed & built along with their new turrets. They were only ready for installation in KGV herself in 1939/40.

Then there is the issue of whether industry could produce the new guns / turrets / armour necessary on top of what was already needed for the other reconstructions and new construction. These industries were run down inter war due to a lack of orders and it took time to get them back up and running. They were limiting factors in battleship production and reconstruction.

When it came to the Italian ships, their bow sections simply had a new structure built outside the original structure. Their existing 12"/46 (305mm) guns were remanufactured as 320mm/44 and fitted to the same turrets with the guns generating a modest 13% increase in muzzle energy. The increase in the forces involved in going from the 13.5" of Tiger to the 14" of the KGV would, I believe, have been far greater.

So while Tiger might appear useful in WW2, she was essentially a 30 year old pre-Jutland design, requiring a huge, for the time, amount of money spent to reactivate her that would still have produced a mediocre ship useful for little more than convoy escort.

The 14" gun was specifically designed to fit in the 13.5 gun cradles

 

[EwenS]

The 14" gun was specifically designed to fit in the 13.5 gun cradles

Do you have a source for that? Not seen that before.

The 14" Mk.VII was designed from 1935 with new turrets designed to carry them.

By that point in time the only 13.5" turrets left in service were on the gunnery training ship Iron Duke plus a couple in store. Why would they even consider designing a gun to back fit to mounts no longer in service?

Edit. Designing the new twin turret caused delays in the KGV build programme. Odd that if old designs for at least some parts of it could be wheeled out and incorporated that it doesnt appear to have been done.

 

[Dilandu]

By that point in time the only 13.5" turrets left in service were on the gunnery training ship Iron Duke plus a couple in store. Why would they even consider designing a gun to back fit to mounts no longer in service?

I suspect that Tallguy may be confusing the 14-inch BL Mk VII naval gun (from KGV's) with earlier 14-inch BL Mk III guns (used in WW1 as railway artillery). I recall that when several 14-inch railway guns carriages were found in storage in 1939 (quite a story for itself - British literally forgot completely about those massive weapons!) there were no 14-inch barrels left, and they were re-equipped with 13.5-inch Mark V, which were close enough to fit into their cradles.

 

[tallguy]

Do you have a source for that? Not seen that before.

The 14" Mk.VII was designed from 1935 with new turrets designed to carry them.

By that point in time the only 13.5" turrets left in service were on the gunnery training ship Iron Duke plus a couple in store. Why would they even consider designing a gun to back fit to mounts no longer in service?

Edit. Designing the new twin turret caused delays in the KGV build programme. Odd that if old designs for at least some parts of it could be wheeled out and incorporated that it doesnt appear to have been done.

Trials of 14" in Iron Duke

 

[tallguy]

I suspect that Tallguy may be confusing the 14-inch BL Mk VII naval gun (from KGV's) with earlier 14-inch BL Mk III guns (used in WW1 as railway artillery). I recall that when several 14-inch railway guns carriages were found in storage in 1939 (quite a story for itself - British literally forgot completely about those massive weapons!) there were no 14-inch barrels left, and they were re-equipped with 13.5-inch Mark V, which were close enough to fit into their cradles.

Not confused at all. 14s were designed to fit the Iron Dukes cradles for testing

 

[Owens Z]

I thank the above contributors for their comments. Some fixate on a secondary matter: the plausibility of HMS Tiger surviving for a few more years, to a time when NO weapon would be thrown away, by anyone. In the same sense that with war clouds gathering, antique USS Arkansas (older than Tiger) became safe from the scrapping that was otherwise warranted. The prim accountant-like observations here are completely wrong for the period in question. When you're desperate, you do what you have to do.

The comment of the noted Dilandu proves my point. In the UK's dire time of need, the railway mountings uncovered in warehouses, with their original 14-inch naval guns long gone, hurriedly had Tiger-type 13.5-inch guns placed in them, and (yes, with some effort) those fitted fine. The railway guns immediately were put to work shelling Germans around Calais.

The main point of my post is not political or financial, but technical: had Tiger's scrapping not happened for whatever reason, how would she best be modernized for service in the foreseen war? I agree that designing and building all-new turrets, or adding an extra four King George V B-turrets to the production line, would take the Tiger bis effort beyond the "moderate middle way" that I advocate. We know there were twin 13.5- and 15-inch turrets sitting in UK warehouses, and I was going to check whether there were also twin 14-inch turrets gathering dust (perhaps from Almirante Cochrane converted to carrier HMS Eagle?). But Tallguy's info (thank you, T) reassures me that new King George V-type 14-inch guns could, with effort, be fitted into Tiger's turrets. So I stand by my original post.

Just to be clear, even if no work at all was done (or, as some here maintain, was possible) other than scraping off rust and barnacles, I still say that a surviving HMS Tiger would have been sent to war with her coal and her 13.5s (which was a hard-hitting gun), and would have served honorably and usefully.

 

[Colonial-Marine]

At a bare minimum for air defense, I'd expect twin 4"/45 anti-aircraft guns to replace the existing older single 4"/45 mounts, several quadruple or octuple multiple 2pdr (40mm) "Pom Poms" mounts, and some quadruple Vickers .50 caliber machine gun mounts. Depending on how things go, those might later be replaced with 20mm Oerlikons as they often were on ships had had them.

 

[Owens Z]

Thanks, Pvt Vasquez. While I am relatively indifferent to the low-angle 6-inch guns of the original Tiger, and approve removing some of those to help with weight loss or for any other reason, like everybody else I know that old anti-aircraft efforts had to be massively upgraded for WW2 threats. I didn't add new turrets for high-angle 4-inch or 5.25-inch AA guns to Tiger bis because I deemed the design effort would necessarily take that outside the "moderate middle way" that I think is best. And the several new magazines needed would, I fear, become another explosion threat: British warships in particular don't need more of those. And also, (as I had said, hindsight is allowed) British heavy AA guns proved to be not especially effective in action. A Tiger bis with only light AA cannon caught steaming off Trincomalee by planes from the Japanese carriers of the April 1942 Indian Ocean raid would not have lasted one hour. A Tiger bis with light AA cannon plus as many 4-inch or 5.25-inch AA guns as could fit would not have lasted one hour. So no use worrying about it. Put out to sea and fight.

 

[Owens Z]

Noted expert and keeper of the excellent NavWeaps site, Tony DiGiulian, reminds me that the Royal Navy's WW2-era twin 4"/45 cal dual-purpose gun, which Colonial-Marine recommends, had little or no deck penetration, unlike what I had wrongly thought, and thus could be bolted to the weather deck wherever convenient, not just be constricted to replacing HMS Tiger's few obsolete 4" AA guns one-for-one. No major below-decks reconstruction would be needed, in keeping with my preferred moderate course. Therefore, instead of mostly agreeing with Colonial-Marine, I now fully agree with him. Add several 4"/45s to Tiger bis, removing 6" casemates as needed for balance. Even so, I suspect that the practical wartime difference between a wall of light AA cannon vs. a wall of light AA cannon plus several 4"/45s is small. My gold standard of comparison here is with (early war) the USN's 5"/38 cal, and (late war) the USN's 5"/38 cal with British-inspired, American-manufactured VT fuzes. I'm a fan of the old girl, and she might have had battle damage repaired in a US yard like many other British warships did, but Tiger bis would not be getting those guns.

 

[Dilandu]

Okay, let's explore the main guns options. I see three potential scenarios: retain old 343-mm, rebore old 343-mm to 356-mm, replace them with new 356-mm.

1) Retain the old 343-mm/45. Using supercharges (like on R-class battleships), the range on max 20 degrees elevation could likely be increased to 25-26 km, which is sufficient (just sufficient) for WW2 battleship. The salvo weight would be about 5112 kg.

For compairson, Renown-class battlecruiser have a salvo of 5214 kg, so our "Tiger" would NOT be under-armed with her original guns. She may, however, have problems with penetration; RN WW1 era Greenboys weren't exactly the shining light amongst APC munitions.

2) Re-bore and rebuild the guns to use new 356-mm ammo. Technically, this is possible - after all, the bore size would be increased merely to 356-343=13 mm. Which is less than what Italians done with their cannons, when rebored them from 305 to 320 mm.

The lenght of new 356-mm projectile is 156 cm, which is longer than old 343 mm CPC (152 cm), but not critically, so presumably it could be adapted. The muzzle velocity would likely be decreased (due to shorter barrel and reduced powder charges), but 356-mm shell would still have sufficient pehetration. Probably better than supercharged 343-mm. The total salvo would be 5768 kg.

Re-boring the guns would require turret modernization (mainly in terms of handling systems), but PROBABLY could be done without complete rebuild. I'm not sure here.

3) The third options is to fit the 356-mm guns into 343-mm cradles. Technically, it seems to be doable. The lenght difference is about 1,5 meters and weight difference is 4 tons more for 356-mm guns. It would require major turrets rebuild, though. Then the Tiger would essentially have the firepower of 0,8 KGV-class battleship, which is quite impressive.

P.S. For the wartime restoration, I 'd say that supercharging the 343-mm guns seems to be the most practica solution. Maybe a newm heavier 343-mm AP, based on 356-mm shell design, could be developed to remedy the armor penetration problems

 

[Owens Z]

I didn't emphasize the hypothetical HMS Tiger situation vis-a-vis the real-life Hiei situation in my original post, but that was exactly my thinking. As Antony Preston wrote in the 1979 book Sea Power: A Modern Illustrated Military History (p92), "When the British saw the rebuilt Kongos (which they had designed originally) they reflected ruefully that they could have done the same with the battlecruiser Tiger, which had been prematurely scrapped in 1933 [sic] to comply with the Washington Treaty [sic]."

Among my recommended updates to a surviving Tiger bis, I did consider remodeling the old ram bow into a modern clipper bow, for better seakeeping at speed, but I chickened out and didn't mention it, thinking that I was already pushing my luck on the amount of work needed for the "moderate middle way" refit that I think would have been best. If remodeling the bow could have been done relatively cheaply and easily, then I am all for that.

 

[Owens Z]

The Hiei and the other Kongos, despite their elaborate and expensive reconstructions, didn't need to worry about a main armament upgrade because their Vickers-designed 14-inch guns remained in general service with the IJN through the end of WW2, including aboard the Fuso class and Ise class battleships. The 13.5-inch, while a fine gun, was no longer in service with the Royal Navy by the late 1930's. HMS Iron Duke had been demilitarized and in any case was run aground very early in WW2 by German bombs. There were 13.5 barrels and shells ashore in warehouses, and some of these were subsequently used to fire on the Germans around Calais from the Dover area. So a surviving HMS Tiger could have made do with her original armament, as I think Dilandu prefers if supercharges could have been used in their chambers. Still would be a hard-hitting ship, even without the modern KGV 14-inch guns that I recommend.

 

[Dilandu]

So a surviving HMS Tiger could have made do with her original armament, as I think Dilandu prefers if supercharges could have been used in their chambers. Still would be a hard-hitting ship, even without the modern KGV 14-inch guns that I recommend.

Yep. She would be at least as powerful as refitted Renown - and additional battlecruiser would surely be handy.

 

[lostness]

Battlecruiser HMS Tiger, commissioned in 1914, was scrapped in 1932 after distinguished service to the Royal Navy. What if she hadn't been scrapped, and (being by all accounts in good shape) survived five more years, when the looming threat from Japan, Italy, and Germany was becoming obvious? Perhaps to comply with the London Naval Treaty she was demilitarized in 1932 rather than scrapped, like the Hiei of similar design; or a tired R-class battleship was scrapped in her place; or she simply languished rusting in some backwater. (No aspersion is cast here on Britain's compliance with signed arms limitation treaties, which was much stricter than that of most signatories).

Using our knowledge of the times and the technologies, and, yes, the benefit of hindsight, what would be the optimum course to get Tiger into shape to fight in the coming war, if you agree with me that the big ship would be useful? I suggest to you that a middle course would have been wisest, between the barest minimum (scrape the barnacles, slap on a new coat of paint, enlist a few hundred coal stokers, and sail to war to do her best) and the extreme and expensive reconstructions of the Kongo class and the Andrea Dorias, which among many other things lengthened and re-formed the entire hulls. I will call my refitted warship HMS Tiger bis, for clarity. Tiger bis would be about two years off her feet (say, mid-1937 to mid-1939) and would have the following work done:

· strip out the original direct-drive steam turbines, coal-fired boilers, and coal bunkers, and replace with modern geared steam turbines, new lower-rpm propellers, and oil-fired boilers

· entirely delete the underwater torpedo tubes and torpedo magazines

· replace the dated 13.5-inch guns (1410 lb Greenboy shells) with eight 14-inch Mark VII guns (1590 lb shells) as used on the new King George V battleships, and substantially increase the max elevation from 20°

· add modest bulges to the sides, to better resist torpedo hits

· drizzle anti-aircraft cannon around the weather deck, and [later] increase their number and update the weapons as the Second World War progresses, like all other capital ships did

· update communications, and [later] add radars and electronic warfare gear as those become available


Although they were out of production, Britain had some stores of 13.5 shells and guns left in the late 1930's, but I still think a firepower upgrade is indicated. Weight of metal on the enemy from Tiger bis's broadside is usefully more than the Renown class's 11,628 lbs (and also more than the Scharnhorsts, updated Kongos, etc.). No doubt during the refit, judicious additions of deck armor would be done, complementing the additions done post-Jutland, but I don't want Tiger bis to be heavier than, say, 4% above her 1918 full-load displacement, both for reasons of economy and also to avoid the serious weight problems of, for example, the Queen Elizabeth class and HMS Vanguard (as I said, hindsight is allowed). Some 6-inch casemate guns can be taken off as needed to help with this weight goal. There were no aircraft aboard after the two flying-off platforms for Sopwiths had been discarded, but I affirm Tiger bis has no aircraft handling capability. The ship is faster than her 29-knot maximum when new. Tiger bis is more robust and hit-tolerant than the flimsy Renowns (which nonetheless fought valiantly).

What do you all think of my suggested refit? Please weigh in. I believe this ship would have been worthwhile for many roles in WW2 against Japan, Italy, and Germany. I don't know whether Tiger bis would have survived the savage fighting (and speculation on that is welcome), but if she did, she would today be a proud museum ship in Portsmouth to visit, the last of the Splendid Cats, with funky red, white, and blue artwork on her hull inspired by the dazzle painting of yesteryear.

Such a rebuild has been something I thought of often. Tiger was the most beautiful of ships.

As a side tangent, and I bring this up because of the mention of upgrading the Tiger's 13.5" to 14" guns: A similar case study would be a modernization of the HMS Canada / Chilean Almirante Latorre. The Latorre was in good enough condition for the US to consider purchasing her after Pearl Harbor.

Similar to the Iron Duke class, but with lesser armour and 14" instead of 13.5" guns, the Canada / Lotorre was slightly larger--in fact, by weight, she was only second in displacement to the Queen Elizabeth class. With 37000SHP and a 23knot speed, she was the prototype for the fast battleship of the Queen Elizabeth class.

My envision for refit would be: removal of Q turret and the 6" casements. This frees up a lot of weight, and gives easy access to upgrade the engineering aspects. Within her engineering space, she would have been able to upgrade to a modern 80,000SHP oil fired boiler within the same space as her coal fired. With Q-Turret removed an addition boiler compartment could have been added for maybe an addition 20,00SHP for 100,000SHP. Likely speed would have been a respectable 27knots, with boilers exhausting from two funnels (or a proper 25knots with the 80,000SHP).

The 14" guns were good. Their performance was similar to those on the HMS King George V class--this when comparing the WW1 ammunition used vs. the modern WW2 era used in the KGV. Adjustments to the guns elevation and loading would provide her with a range performance equal to the KGV class. Few modifications would have been required for the guns to accept the modern 14" shells. The removal of the 6" casements would be compensated with the addition of 4.5" or 5.5" guns in twin turrets. Eight twin dual purpose 4.5" guns similar to those on the QE class would most likely be the most adequate solution, for 16 guns total. AA would evolve as typical to British service as the war progresses.

The Lotorre was armoured somewhat similar to German battlecruisers--more adequate than British battlecruisers, but less than battleships. Deck armour and bulkheads over and around the magazines and machinery spaces would be increased, as well as around the barbettes, and additional armour on the turret faces and tops. Most likely, the best that would be achieved would be good protection against 11" guns but still inadequate against 15". The removal of the underwater torpedo tubes would help in shoring up the underwater protection (improved water tight spaces), and bulges would be necessary to provide some form of protection against torpedoes. The fine balance between maintaining a respectable speed and having respectable bulge protection would require careful planning on modifying the former coal bunkers into oil bunkers (the coal bunkers on older battleships were places outboard, by such virtue giving additional absorption space for incoming shells. Oil was less generous in the shock/shell absorption it provided).

Bridge and fire control would require modernization. This part here I would go with the Italian job done on the Conte di Cavour / Andrea Doria modernizations, opposed to the much more extensive QEII, though the compromise would realistically hinder the increase in radar and other communications equipment. Fire control would follow RN standards, and likely find itself similar to the QUII specs.

Time and budget: cutting back the bow and rebuilding it, making the ship 15-20ft longer with a finer prow. The Italians grafted over the original bow, which brought issues, cutting back and rebuilding offers a more uniform and structurally sound solution. The finer lines of the longer bow will give better economy and speed. If the British habit of wanting to allow a 0` forward line of fire, and an 'Atlantic' bow is installed, the ship could be made to weather rough seas better than the KGV or QUII class--- and war experience demonstrated that there was never a need to fire straight ahead at 0` elevation. Such a modification would likely give an additional 15% cruising range and make maintaining speed easier, with a slight decrease in turn radius.

The end result would be a moderately fast battleship (27knots) that could keep pace with the fast carriers (much better than the QU2 class), with a satisfactory heavy gun armament (eight 14" firing a 1,500lb shell with a range around 30,000yards with a 32.5` elevation). Armour would be adequate against cruisers and the 'pocket battleships,' and enough to face off against the Cavour / Doria, but as with the Hood, Repulse and Renown, short of holding against more weightier opponents. Underwater protection would still be vulnerable, but, like the carriers, she would rely more or speed (and unlike Courageous or Ark Royal, she would have some element of protection and redundancy).

Overall, the Canada / Lotorre would have been a better investment for modification than the Tiger, and be a good compliment to the Renown and Repulse as a fast escort for the British carriers. She would have been more adequate for the demands of the Mediterranean than the QU2 because of speed, or, if left with 80,000SHP and a 25knot (still better than the 23.5knot the QE2 had to settle with) and, if provisioned with additional fuel, would have provided a satisfactory Pacific fleet service akin to the older US battleships.

The Tiger, honestly assessed, would have been better off as an aircraft carrier than the Eagle (which was built off of Canada / Lotorre's sister Almirante Cochrane) offering a faster, longer haul, and likely a 25% increase in both aircraft capacity and associated fuel and munitions. But, of course, history had Eagle become the first standard carrier design while Tiger was still hoisting the flag.

 

[Dilandu]

Such a rebuild has been something I thought of often. Tiger was the most beautiful of ships.

Fully agree!

 

[Owens Z]

Such a rebuild has been something I thought of often. Tiger was the most beautiful of ships.

The Tiger, honestly assessed, would have been better off as an aircraft carrier than the Eagle (which was built off of Canada / Lotorre's sister Almirante Cochrane) offering a faster, longer haul, and likely a 25% increase in both aircraft capacity and associated fuel and munitions. But, of course, history had Eagle become the first standard carrier design while Tiger was still hoisting the flag.

Thanks, lostness. The months following the Pearl Harbor attack and Nazi Germany's declaration of war were of course a nerve-racking time in the United States. When I learned several years ago that the American government had expressed interest then in purchasing the British-built Chilean battleship Almirante Latorre as an immediate reinforcement for the battered US Navy (as mentioned for example in the ship's current Wikipedia article), this seemed a wise course to help deal with the emergency, assuming that its 14-inch guns could be quickly modified to accommodate USN Mark 16 or Mark 20 1500 lb AP shells instead of Chile's remaining supply of 1595 lb Greenboys. But note that, as I read with interest last year, the eponymous chapter of The World of the Battleship: The Design & Careers of Capital Ships of the World's Navies (Seaforth, 2018) specifically denies that any such thing occurred. This detailed chapter's two authors are Chilean historians. Page 265: "It should at this point be stated that there is no evidence in Chilean sources to support the oft-repeated claim in English-language sources that the United States approached Chile with a view to purchasing Latorre [or other warships]..."

I don't know whether Japanese submarines ever reached Chile's waters in WW2, like German cruisers did in WW1. In the 2.5 years between the destruction of those German cruisers and the entry of the USA into the war against Germany, IJN warships actively patrolled the extreme eastern Pacific (e.g. in 1915 armored cruiser Asama accidentally ran aground in Bahía Tortugas off Mexico's Baja California Peninsula), and the IJN made some training voyages to South America in the interwar years, so Chile knew that the Japanese could find them if they wanted. With the hubris of what the Japanese themselves retrospectively called early 1942's "victory disease", when Tojo was considering which cronies to assign as military governors of Canada's and the USA's west coasts, Mexico, Panama, and Colombia, it was justified for Chileans to believe that Almirante Latorre was needed at home.

As to the substance of your post, lostness, I had reasoned that with war clouds gathering, a counterfactual HMS Tiger bis would put to sea in 1939 after a two-year refit of relatively moderate scope. A 30-knot battlecruiser would have had intensive and worthwhile service against Italy, Germany, and Japan (and very possibly might not have survived the war). A tired, slow battleship acquired by the Royal Navy in early 1942, if we postulate for a moment that Chile agreed, would certainly not begin a two-year reconstruction then. Instead, HMS Canada back on the team would be anchored off Kenya, sitting out the savage fighting of 1942 along with the tired, slow R-class battleships. A "better investment" for the UK? No. And to respond to EwenS's post #7 in this thread, sacrificing one R-class battleship in place of Tiger is not "plainly absurd"—it's obviously the better choice for WW2 (with the benefit of hindsight).

Lostness, you are mistaken that Almirante Latorre/Canada would need conversion from coal to fuel oil. That had already been done during the ship's extensive 1929-31 reconstruction in Plymouth, England.

I heartily agree with lostness, Dilandu, and others that HMS Tiger was a majestic beauty. This battlecruiser's premature scrapping in 1932 was an aesthetic loss as well as a loss of fighting power that the British would rue just a few years later.

 

[zoeafr]

Do you have a source for that? Not seen that before.

The 14" Mk.VII was designed from 1935 with new turrets designed to carry them.

By that point in time the only 13.5" turrets left in service were on the gunnery training ship Iron Duke plus a couple in store. Why would they even consider designing a gun to back fit to mounts no longer in service?

Edit. Designing the new twin turret caused delays in the KGV build programme. Odd that if old designs for at least some parts of it could be wheeled out and incorporated that it doesnt appear to have been done.

Hmmm....... Remember the battleship Canada? it had 14 in. turrets, ableit of a weaker protection and the same old design...It isn't out of possibilities that those 14 in. could have been fitted into the 13.5 in barbettes. The Canada ( latter re-named Almirante Latorre when Chile took possession after the war), was simply a lightly stretched Iron Duke class battleship. Now, we're a far cry from the KGV 14 in. 50 cal. guns, but, for the sake of argument

 

[zoeafr]

My view on this is right up there with most of you; although the Tiger was a very fine and nice looking battlecruiser, and actually did replace the Hood in the twenties for a period, there wasn't enough funds for a ship which, to make something decent of it, would have had to be reconstructed. Now, having said that, a modest ''refit'' could have happened and may not have costed that much. So, for fun here, and to give some form of use to that ship, torpedo bulges would have been a must, the removal of some of the secondary 6 in. guns ( 6 of them, like on the Warspite) and the torpedo tubes to accomodate better anti-aircraft armament, updated telemetry, and some form of upgrade of the boilers could have made it a fine escort battlecruiser for the aircraft carriers the Royal navy had at the time. Also, some upgrade to the main gun elevation would have helped without breaking the bank. But that would have meant sacrificing another maybe more useful ship to stay within the treaty

 

[Dilandu]

Hmmm....... Remember the battleship Canada? it had 14 in. turrets, ableit of a weaker protection and the same old design...It isn't out of possibilities that those 14 in. could have been fitted into the 13.5 in barbettes. The Canada ( latter re-named Almirante Latorre when Chile took possession after the war), was simply a lightly stretched Iron Duke class battleship. Now, we're a far cry from the KGV 14 in. 50 cal. guns, but, for the sake of argument

Hm. I'm not sure that any 14-inch barrel from Chilean order survived past mid-1920s. The 14-inch wasn't a common British caliber at this time, and it just wasn't practical to retain them.

Also, some upgrade to the main gun elevation would have helped without breaking the bank. But that would have meant sacrificing another maybe more useful ship to stay within the treaty

Well, my idea was actually that it would be turned into training ship instead of Iron Duke, and hastly restored to combat-ready condition in 1938-1940 (after it became obvious that neither Japan nor Italy would join the treaty system).

 

[zoeafr]

Hm. I'm not sure that any 14-inch barrel from Chilean order survived past mid-1920s. The 14-inch wasn't a common British caliber at this time, and it just wasn't practical to retain them.


Well, my idea was actually that it would be turned into training ship instead of Iron Duke, and hastly restored to combat-ready condition in 1938-1940 (after it became obvious that neither Japan nor Italy would join the treaty system).

I understand that those 14 in. were not stored since they were on that ship until his voyage to the scrapyard in the 1950's or 60's; I was just try to make a point that it would have theoretically possible to put 14's on the tiger with the Canada's model of canons; that being said, I don't see the point in doing that And to the point of the Iron Duke's training duties to sort of preserve one more ship, yes, I think it would have made more sense in using the Tiger since it already had that duty; and as I said with little mods it could have made a fine escort battlecruiser for the carriers. The Iron Duke wasn't of much use being a pontoon.....

 

[BlackBat242]

I understand that those 14 in. were not stored since they were on that ship until his voyage to the scrapyard in the 1950's or 60's; I was just try to make a point that it would have theoretically possible to put 14's on the tiger with the Canada's model of canons; that being said, I don't see the point in doing that And to the point of the Iron Duke's training duties to sort of preserve one more ship, yes, I think it would have made more sense in using the Tiger since it already had that duty; and as I said with little mods it could have made a fine escort battlecruiser for the carriers. The Iron Duke wasn't of much use being a pontoon.....

He is referring to the fact that the Chilean order was for TWO basically identical battleships - Canada/Almirante Latorre and Almirante Cochrane - which was suspended incomplete then converted to the aircraft carrier HMS Eagle after war's end.

He is wondering about any 14" guns that might have been made for Cochrane before the UK and Chile decided that the RN could have the incomplete hull - it is my understanding that none of those guns were actually built, or if some were they were diverted for other uses.

 

[Dilandu]

He is wondering about any 14" guns that might have been made for Cochrane before the UK and Chile decided that the RN could have the incomplete hull - it is my understanding that none of those guns were actually built, or if some were they were diverted for other uses.

As far as I know, all unused 14-inch barrels made for Cochrane were scrapped in mid-1920s. As well as barrels from three raiway guns (the carriages themselves survived). So by 1939 there weren't any old 14-inch barrels in UK.

 

[zoeafr]

He is referring to the fact that the Chilean order was for TWO basically identical battleships - Canada/Almirante Latorre and Almirante Cochrane - which was suspended incomplete then converted to the aircraft carrier HMS Eagle after war's end.

He is wondering about any 14" guns that might have been made for Cochrane before the UK and Chile decided that the RN could have the incomplete hull - it is my understanding that none of those guns were actually built, or if some were they were diverted for other uses.

Hmmm... I was simply making the case that it could have been an option to have 14 in. guns installed without changing the turrets and barbettes; whether the Cochrane guns were already available or not doesn't matter in my view since there would have been no real benefit; supercharging the 13.5 in and work on the ability to load at the full 20 degrees elevation would have yelded somewhat better results at a lesser cost. The whole idea for a battlecruiser at that point would have been the ability to provide fast escort to the carriers or other duties mainly for anti-aicraft duties with a refit of pom-poms and other anti-aircraft armament, torpedo bulges ( which all the R battleships received), some plating on the decks and turrets, the removal of 4 of the 12 6 in. and the torpedo tubes to offset the added weight. and the conversion to oil only boilers along with a litte work on them to compensate some of the lost speed because of the bulges; it's history showed that it had some endurance taking 11 in. shots. unfortunately, the admiralty had the dogma of not being convinced an aircraft could sink a ship, until demonstrated in South East Asia in 41'. That would have made some good use of the tiger....contrary to the Iron Duke's sorry last years of life.

 

[Dilandu]

supercharging the 13.5 in and work on the ability to load at the full 20 degrees elevation would have yelded somewhat better results at a lesser cost.

Here I agree completely.

and the conversion to oil only boilers along with a litte work on them to compensate some of the lost speed because of the bulges;

Well, technically no one forbade from installing new boilers onboard training ships - "for training purposes" - providing that max speed would not be more than 18 knots (on the other hands, who would care to check if the training ship in question never moves even at allowed max speed?)

 

[zoeafr]

Here I agree completely.


Well, technically no one forbade from installing new boilers onboard training ships - "for training purposes" - providing that max speed would not be more than 18 knots (on the other hands, who would care to check if the training ship in question never moves even at allowed max speed?)

Apparently, the Royal Navy people were deadset on sticking with the narrow interpretation of the treaty.....
It only shows the degree of dogma the admiralty had, including Churchill, lord of admiralty at that point

 

[Dilandu]

So my concept:

* In 1930, Royal Navy decided to retain "Tiger" instead of "Iron Duke" (having suspicions about Japanese willingness to disarm Hiei). They remove the Q turret, part of armor plates, and half of her boilers. As a bit of tweaking the Treaty rules, bulges installed on "Tiger" (nothing in the Treaty forbade from installing bulges on training ships)

* After Japan leave the League of Nations in early 1930s and it became clear that naval limitation system would not hold Japanese for long, Royal Navy quietly replace the remaining "Tiger" boilers with modern Admiralty models - ostensibly, to "provide better training capacity with more modern equipment", but actually restoring her max speed to 28+ knots.

* When Japan and Italy refuse to sign Second London Treaty in 1937, Royal Navy make preparation to return "Tiger" into combat-ready condition as fast as possible (probably at the expense of Royal Oak modernization), including increasing in her deck armor over magazines and machinery.

* In 1938-1940, the "Tiger" is quickly re-armed, her Q turret put back in place, her side armor restored, more or less modern fire control installed and some DP gun (four 102/45 QF Mk XVI) installed

 

[Dilandu]

Apparently, the Royal Navy people were deadset on sticking with the narrow interpretation of the treaty.....
It only shows the degree of dogma the admiralty had, including Churchill, lord of admiralty at that point

They basically considered the Treaty system to be the best outcome Britain could hope for, and thus were paranoid about ANY possible violations, or even actions that may cause others to call for re-evaluation of the Treaty.

 

[zoeafr]

So my concept:

* In 1930, Royal Navy decided to retain "Tiger" instead of "Iron Duke" (having suspicions about Japanese willingness to disarm Hiei). They remove the Q turret, part of armor plates, and half of her boilers. As a bit of tweaking the Treaty rules, bulges installed on "Tiger" (nothing in the Treaty forbade from installing bulges on training ships)

* After Japan leave the League of Nations in early 1930s and it became clear that naval limitation system would not hold Japanese for long, Royal Navy quietly replace the remaining "Tiger" boilers with modern Admiralty models - ostensibly, to "provide better training capacity with more modern equipment", but actually restoring her max speed to 28+ knots.

* When Japan and Italy refuse to sign Second London Treaty in 1937, Royal Navy make preparation to return "Tiger" into combat-ready condition as fast as possible (probably at the expense of Royal Oak modernization), including increasing in her deck armor over magazines and machinery.

* In 1938-1940, the "Tiger" is quickly re-armed, her Q turret put back in place, her side armor restored, more or less modern fire control installed and some DP gun (four 102/45 QF Mk XVI) installed

Makes more sense than the decisions they took; more AA weaponry would have to be installed though, and since your option is to install the QF guns, then all 6 in. would need to be remove for the sake of the added weight....

 

[Dilandu]

Makes more sense than the decisions they took; more AA weaponry would have to be installed though, and since your option is to install the QF guns, then all 6 in. would need to be remove for the sake of the added weight....

Well, I went for the simplest restoration that could be achieved in minimal time. So I suppose SOME 6-inch guns would be retained (about 8 of them) with four dual 102/45 and a pair of octuple Pom-Pom's would be added. Essentially like the Revenge-class refit.

 

[zoeafr]

Well, I went for the simplest restoration that could be achieved in minimal time. So I suppose SOME 6-inch guns would be retained (about 8 of them) with four dual 102/45 and a pair of octuple Pom-Pom's would be added. Essentially like the Revenge-class refit.

That might have created some weight problems and have the ship deeper in the water with more drag...
I would venture 6 QF45's, 4 pom-pom octopules, 4 quads, and about twelve singles spread over; that would require the removal of all 12 6 in. guns, which always had limited use. It also would create some free weight to add plating on the quarter deck to cover the magazines and machinery, and the turret plating which was a bit weak. it basically resembles what they did with the Hood, in late 40'.

 

[EwenS]

They basically considered the Treaty system to be the best outcome Britain could hope for, and thus were paranoid about ANY possible violations, or even actions that may cause others to call for re-evaluation of the Treaty.

And yet there are cases when Britain does appear to have broken the rules in the Treaties. No one seems to be able to explain how they got away with fitting armour to the depot ships Woolwich & Maidstone during the period of LNT 1930 which seems like a clear breach of Article VIII(c). Maybe a case of "oh well it's buried in the ship so no one will notice".

The Treaties were like any other legal agreement, open to interpretation in certain respects, with different nations having different interpretations, as Britain & the US had regarding increasing gun elevation. Take a look at the length of these Treaties. Today lawyers would ensure they ran to hundreds of pages trying to pin down every possible eventuality. It was a different era.

As for improvements to retained capital ships regard has to be had to WNT 1922 Part 3 Section I(d) which reads:-

"d) No retained capital ships or aircraft-carriers shall be reconstructed except for the purpose of providing means of defence against air and submarine attack, and subject to the following rules: the Contracting Powers may, for that purpose, equip existing tonnage with bulge or blister or anti-air attack deck protection, providing the increase of displacement thus effected does not exceed 3,000 tons (3,048 metric tons) displacement for each ship. No alterations in side armour, in calibre, number or general type of mounting of main armament shall be permitted except:

(1) in the case of France and Italy, which countries within the limits allowed for bulge may increase their armour protection and the calibre of the guns now carried on their existing capital ships so as not to exceed 16 inches (406 millimetres) and;​

(2) the British Empire shall be permitted to complete, in the case of the Renown, the alterations to armour that have already been commenced but temporarily suspended."​

Note in particular "No alterations in side armour, in calibre, number or general type of mounting of main armament shall be permitted"

The very last part of that is where the US and Britain differed in their interpretations about increasing the elevation of the guns. The US of course had a vested interest in justifying it as it allowed them to leapfrog what the RN already had.

As for substituting Tiger for Iron Duke after LNT 1930 regard has to be had to what it was necessary to carry out.

"1. Capital ships
The following is to be carried out:​

(1) Removal of main armament guns, revolving parts of all barbettes and turrets; machinery for operating turrets; but three turrets with their armament may be retained in each ship;​

(2) Removal of all ammunition and explosives in excess of the quantity required for target practice training for the guns remaining on board;​

(3) Removal of conning tower and the side armour belt between the foremost and aftermost barbettes;​

(4) Removal or mutilation of all torpedo tubes;​

(5) Removal or mutilation on board of all boilers in excess of the number required for a maximum speed of eighteen knots."​

Note the requirement to remove the side armour between foremost and aftmost barbettes i.e ALL of it. It doesn't say "part thereof". And to get to that armour, you would have to remove any bulge fitted in the 1920s. Other nations would be asking a lot of questions about your intentions if you suddenly replaced or added highly visible protective bulges to what was intended to be a non-combatant training ship during the duration of the 1930 Treaty.