USS Bermuda, ex HMS Rodney, in USN WW2 service

[JoeCalPo]

 

[JoeCalPo]

This was my interpretation of what could have been done with Nelson/Rodney if they were traded to the US after Tirpitz was sunk while sailing to Norway in early 1942. The USN wants/needs battleships, these two need work but can be ready long before the ships sunk at Pearl, and the RN's 15" battleships plus the KGVs on the way are enough to handle Scharn and Gnei and the panzercruisers. The USN gives a few cruisers and older destroyers in exchange, boosting the patrol/escort fleet of the RN.
5"/38 twins in place of the 6" twins (which the RN uses for a couple more small light cruisers), 40mms and 20mms, USN radar and directors.

Here's the stern, where most of the changes are concentrated.

 

[Dilandu]

Too few DP guns. Those 6-inch turrets weighted almost 76 tons, while 5-inch dual DP Mark 32 mount - only 47 tons.

 

[EwenS]

The USN gives a few cruisers and older destroyers in exchange, boosting the patrol/escort fleet of the RN.

1942 the USN couldn’t spare any ships.

Cruisers - Atlanta and Cleveland classes were only starting to complete. 9 Cleveland class hulls diverted to CVL.

Older destroyers - none to spare. In early 1942 the flow of escort type ships was from the RN to the USN to bolster defences against the east coast Kriegsmarine submarine campaign, Operation Drumbeat. For example 10 Flower class transferred to the USN Feb/March and 24 trawlers loaned at the same time.

 

[JoeCalPo]

Too few DP guns. Those 6-inch turrets weighted almost 76 tons, while 5-inch dual DP Mark 32 mount - only 47 tons.

Rebuilding the ships to fit additional turrets requires much more work than adapting the existing barbettes. The idea is to get them into service quickly to replace the Pearl Harbor losses.

 

[JoeCalPo]

1942 the USN couldn’t spare any ships.

Cruisers - Atlanta and Cleveland classes were only starting to complete. 9 Cleveland class hulls diverted to CVL.

Older destroyers - none to spare. In early 1942 the flow of escort type ships was from the RN to the USN to bolster defences against the east coast Kriegsmarine submarine campaign, Operation Drumbeat. For example 10 Flower class transferred to the USN Feb/March and 24 trawlers loaned at the same time.

Ah yes, I did forget one additional detail of my scenario: Germany and Italy don't declare war on the US after Pearl Harbor, the US takes on protection of Bermuda and the Caribbean to the US, so no submarines off the US East Coast so reduced need for escorts. For cruisers I considered two Omahas and two of the older 8" like the Pensacolas, useful for convoy protection against surface raiders and submarines, including that they carry aircraft. I'd have to research how many 4 stackers remained; they're old and much as warships, but can cover convoys.

 

[EwenS]

Ah yes, I did forget one additional detail of my scenario: Germany and Italy don't declare war on the US after Pearl Harbor, the US takes on protection of Bermuda and the Caribbean to the US, so no submarines off the US East Coast so reduced need for escorts. For cruisers I considered two Omahas and two of the older 8" like the Pensacolas, useful for convoy protection against surface raiders and submarines, including that they carry aircraft. I'd have to research how many 4 stackers remained; they're old and much as warships, but can cover convoys.

Even without a German/Italian DoW after PH the USN already had an increasing requirement for escorts by virtue of taking responsibility for escorting Atlantic convoys to the Mid Ocean Meeting Point (MOMP) south of Iceland.

https://www.usni.org/magazines/naval-history-magazine/2008/june/navys-atlantic-war-learning-curve

Given the clashes that happened in late 1941 US war with Germany/Italy was only a matter of time. Mid-1942 at the latest IMHO.

 

[Dilandu]

Rebuilding the ships to fit additional turrets requires much more work than adapting the existing barbettes. The idea is to get them into service quickly to replace the Pearl Harbor losses.

Considering that you would need to replace all magazines, elevators and other systems - not to mention, rebuild the whole electric system onboard - I literally see no reason not to install more 5-inch guns.

 

[BlackBat242]

Rebuilding the ships to fit additional turrets requires much more work than adapting the existing barbettes. The idea is to get them into service quickly to replace the Pearl Harbor losses.

The twin 5"/38 mounts were NOT turrets - they had no below-decks rotating structure, so the work required to install them would not be that bad.

 

[T. A. Gardner]

Actually, such a conversion could take as much as a year to complete. The secondary conversion requires not just modified barbettes, but new magazine arrangements, new fire controls, and all the cabling, etc., to operate it. Then, the ship would have to have new generators installed, more added, to provide the AC power-- the RN uses DC--for the mounts and fire controls.

The USN also pretty much did away with ship's boats for the most part, opting to pool these at harbors and with tenders to be given out when ships were in port.

The model, as presented, also does away with the 4.7" HA guns the Rodney & Nelson had aboard.

At the time (early to mid 1942), the 40 mm mounts are barely entering fleet service. You'd have to use the scarce 1.1" quads instead. Even 20mm guns are in short supply at the time.

Then there's the main gun ammunition to consider. The US and RN use different powder, and the shells for their 16" guns are very different in design.

I also suspect the USN would not accept the weak torpedo defense systems these battleships had and would want them bulged. The USN could accept a loss of a couple of knots given their old battleship line were 20 knot (at best) ships, while the Rodney and Nelson are 23 knot.

Then there's the bridge, radar, communications, and other systems to consider. Again, the ship would need a lot more AC power for those.

I'd think a year in the yards is a reasonable period for refitting these ships if this were to happen. If anything, they aren't bringing anything to the table really.

 

[A Tentative Fleet Plan]

I also suspect the USN would not accept the weak torpedo defense systems these battleships had and would want them bulged. The USN could accept a loss of a couple of knots given their old battleship line were 20 knot (at best) ships, while the Rodney and Nelson are 23 knot.

Nelson and Rodney had a modern liquid-backed underwater protection system, hardly weak be any means, and on par or superior to those on the Standard Battleships.

 

[Dilandu]

Actually, such a conversion could take as much as a year to complete. The secondary conversion requires not just modified barbettes, but new magazine arrangements, new fire controls, and all the cabling, etc., to operate it. Then, the ship would have to have new generators installed, more added, to provide the AC power-- the RN uses DC--for the mounts and fire controls.

Exactly. So essentially there is no reason to install more 5-inch DP guns - the amount of work would not be significantly greater, and it would clearly not lenghten the rebuild time at all.

 

[EwenS]

There were a variety of proposals made from July 1936 onwards to reconstruct Nelson & Rodney. See Friedman "British Battleships". Options included from 3 to 5 twin 5.25" mounts per side. The work was esimated to take 2 years depending on exactly what was done (new machinery to gain 2 knots was one option). The final proposals date to late 1943 to mid 1944 and involved the work being done in the USA. The latter are of most interest here.

Secondary armament - remove 6" & 4.7" guns and replace with 6x 5"/54 mounts (i.e. guns intended for the Montana class). When the Admiralty became aware that the latter did not exist it was changed to 8 twin 5"/38. A new superstucture aft of the funnel was planned to carry some of these in a layout reminiscent of the California reconstruction. Control by 4 Mark 37 directors with Type 275 radar laid out in a diamond pattern.

Light AA - 8 octuple pom pom (or quad Bofors) were to be fitted.

When Nelson went to the US in July 1944, the manager of the Philadelphia NY yard estimated that all the work required to her would take until the end of 1945 (about 18 months or so). By late July completion had slipped to mid-1946 (or nearly 2 years). That being after the NY had had a good look at her. It was at that point that Admiral King ensured that the project was killed off, and she underwent a much more austere refit instead that took 6 months followed by another 3 months at Portsmouth for works that couldn't be done in the USA.

So completing the works proposed by the OP in 12 months looks optimistic. And Rodney was in a worse state than Nelson, having missed out on work carried out on Nelson immediately pre-war. Even in 1939 her wiring was described as being "in a particularly bad state". The main problem facing the USN would have been that everything was non-standard. That started with things like screw threads. Brooklyn NY took 10 months to refit the cruiser Delhi and re-equip her with 5x5"/38, but that was largely in 1941 before the US entered WW2.

By way of comparison, California took 15 months to be reconstructed after being salavged and patched up at PH, something that took another 10 months. Tennessee, less heavily damaged at PH was reconstructed in about 9 months. West Virginia took about 2 years after being salvaged and repaired enough to leave PH. All these were carried out at Puget Sound NY. The much more modern Richelieu, which needed less work required 7 months.

The first quad 40mm wasn't produced until July 1942 and it was Sept/ Oct 1942 before they began to be generally fitted with Pacific Fleet carriers getting priority.

 

[T. A. Gardner]

Nelson and Rodney had a modern liquid-backed underwater protection system, hardly weak be any means, and on par or superior to those on the Standard Battleships.

Rodney and Nelson, like other British battleships of the era, had a very shallow torpedo defense system compared to US battleships. The two had an outboard dry compartment, then a 1 1/2" torpedo bulkhead, backed by a fuel oil tank. This system was not only shallow, but would actually increase torpedo damage as there was no liquid loading outboard of the torpedo bulkhead, and the bulkhead itself was a rigid structure that had no flexibility. That is the explosion of the torpedo was likely to deform the bulkhead with full force and in deforming it would allow flooding to enter the ship.

Against torpedoes in use in say, 1918, 1920-ish, this system was just adequate. By 1935, it was inadequate, and completely hopeless by 1942.

One of the major reasons British battleships ended up with such poor torpedo defenses was that available drydocks in England limited the beam of any ship and the RN didn't have or want to put the money into building larger ones. Another was that the system the RN chose, like on Rodney and Nelson was devised to protect against diving shell hits more than torpedoes. These were considered a more serious threat to a battleship than torpedoes.

The US system at the same time was vastly superior to the British one, and that was proven by actual combat results during WW 2. PoW off Singapore had a similar system to that on Rodney and Nelson. It was one of the things that allowed so much flooding so rapidly on that ship. Compare that to the US ships at Pearl Harbor. California took 3 torpedoes similar to those that hit PoW, but took nearly a day and half to settle to the bottom and then only because the ship wasn't in a combat ready state. Had California been it would have survived the damage.
W. Virginia took 7 or 8 torpedo hits, and not one defeated the torpedo defense system. She sank due simply to the damage being so massive it overwhelmed the system with flooding over the torpedo defense system.

In the US system there was a shallow outboard dry compartment followed inboard by three liquid loaded compartments, then another dry compartment before the torpedo bulkhead was reached. All of these compartments used relatively thin steel in their construction and were intentionally designed to allow for deformation of the bulkheads. The torpedo bulkhead was a bit thicker, but it too was designed to allow for some deformation.

This design was intended to absorb the detonation of the torpedo by spreading it out over a wider area while forcing the explosion to work against the mass of the system that could deform and remain intact, either partially or completely. By the time the torpedo holding bulkhead (with a thin bulkhead to contain any potential flooding from cracks just inboard of it) the explosion would be spent and the ship's vitals protected. Diving shells were not considered a particular danger. The system was also much deeper, as much as twice that on a British battleship.

 

[T. A. Gardner]

Exactly. So essentially there is no reason to install more 5-inch DP guns - the amount of work would not be significantly greater, and it would clearly not lenghten the rebuild time at all.

I doubt the US would have accepted just three 5"/38 twin turrets on a battleship however. I could see a mixed battery being used where the three turrets are put in place and then 5"/25 or 5"/38 single guns are added to replace the 4.7" HA guns to bring up the battery to 8 tubes per side the US preferred for battleships.

I can also see these battleships getting bulged. On top of that it is likely the US would install more mechanical ventilation within the ship and weld over every porthole in the hull. Portholes were seen as a weakness and potential route for flooding should the ship list or settle.

I could also see the large (original) torpedo rooms forward being converted into refrigerated stores spaces, again, as the US has different standards for crew accommodations than the British.

Another detail that is very likely to happen is the US welds up every fore to aft hatch in a bulkhead below the second or third deck and installs escape trunks in the machinery spaces. 'Up and over' was the USN norm, unlike the RN that continued to use watertight hatches lower in the ship for movement fore and aft between spaces.

 

[A Tentative Fleet Plan]

Rodney and Nelson, like other British battleships of the era, had a very shallow torpedo defense system compared to US battleships. The two had an outboard dry compartment, then a 1 1/2" torpedo bulkhead, backed by a fuel oil tank. This system was not only shallow, but would actually increase torpedo damage as there was no liquid loading outboard of the torpedo bulkhead, and the bulkhead itself was a rigid structure that had no flexibility. That is the explosion of the torpedo was likely to deform the bulkhead with full force and in deforming it would allow flooding to enter the ship.

Against torpedoes in use in say, 1918, 1920-ish, this system was just adequate. By 1935, it was inadequate, and completely hopeless by 1942.

One of the major reasons British battleships ended up with such poor torpedo defenses was that available drydocks in England limited the beam of any ship and the RN didn't have or want to put the money into building larger ones. Another was that the system the RN chose, like on Rodney and Nelson was devised to protect against diving shell hits more than torpedoes. These were considered a more serious threat to a battleship than torpedoes.

The Nelson-class had a greater beam than any of the Standard Battleships, and we're just over 2ft narrower than the North Carolina-class.

Protection against diving shells was not included in the design of the Nelson-class and was only considered for designs drawn up afterwards.

The US system at the same time was vastly superior to the British one, and that was proven by actual combat results during WW 2. PoW off Singapore had a similar system to that on Rodney and Nelson. It was one of the things that allowed so much flooding so rapidly on that ship. Compare that to the US ships at Pearl Harbor. California took 3 torpedoes similar to those that hit PoW, but took nearly a day and half to settle to the bottom and then only because the ship wasn't in a combat ready state. Had California been it would have survived the damage.
W. Virginia took 7 or 8 torpedo hits, and not one defeated the torpedo defense system. She sank due simply to the damage being so massive it overwhelmed the system with flooding over the torpedo defense system.

Prince of Wales' TDS was not defeated, the ship sank due to a bit outside the TDS on one of the propellor shafts. The TDS of the KGV-class was narrower because it was intended that gasses would be vented upwards into non-essential spaces above the TDS. Gasses venting upwards happened to North Carolina when she was torpedoed, with damage to the STS deck above.

 

[EwenS]

This forensic analysis of the damage to PoW will help you understand the reasons behind the loss of the PoW. The TDS was not to blame. The torpedo hit that crippled her was outwith the TDS. Combined with the restarting of a propellor shaft that wrecked all the bulkheads in the shaft alley back to the engine room, that was what allowed all the water into her.

https://pacificwrecks.com/ships/hms/prince-of-wales/death-of-a-battleship-2012-update.pdf

The Italian battleship Vittorio Veneto suffered from a similarly damaging torpedo hit in March 1941 during the Battle of Cape Matapan. She took on 4,000 tons of water but managed to get underway again and survive.

 

[T. A. Gardner]

This forensic analysis of the damage to PoW will help you understand the reasons behind the loss of the PoW. The TDS was not to blame. The torpedo hit that crippled her was outwith the TDS. Combined with the restarting of a propellor shaft that wrecked all the bulkheads in the shaft alley back to the engine room, that was what allowed all the water into her.

https://pacificwrecks.com/ships/hms/prince-of-wales/death-of-a-battleship-2012-update.pdf

The Italian battleship Vittorio Veneto suffered from a similarly damaging torpedo hit in March 1941 during the Battle of Cape Matapan. She took on 4,000 tons of water but managed to get underway again and survive.

Dunlin and Garzke have what is probably the best analysis of PoW's damage. The torpedo that hit on the starboard side even with B turret, resulted in significant flooding of the torpedo defense system fore and aft of the hit. The torpedo bulkhead also failed partially and flooding occurred in the starboard wing compartments of B turret's magazine.

It was that hit and two others during the second attack that really doomed the ship. All three were on the starboard side. In all three cases there was some flooding inboard of the torpedo bulkhead, particularly with the hit forward by B Turret and aft just outside the citadel of the ship.

Yes, it was the one hit aft on the port side that doomed the ship, but the other torpedo hits weren't insignificant either. The one aft of Y turret on the starboard side, for example, added significantly more flooding aft that exacerbated the port side flooding considerably as the ship settled by the stern.

One of the significant causes of inability to counter the flooding was the design of the ship's electrical system. This was all DC with 6 330 KW generators (steam) and just two 300 kw DC diesel back up / emergency generators. The loss of electrical power almost immediately to much of the aft portion of the ship left it unable to run pumps to counter the flooding. At the same time, loss of ventilation and lighting made it nearly impossible to continue operations below decks and in the main spaces.
The first attack took out 5 of 8 generators including both diesels (one due to flooding, the other due to lack of suction for cooling water).

 

[JoeCalPo]

Thank you for the additional details on my model. If I were to create another USN Nelson, I'd start with a time period - 1942 or 1945.
1942 would have minor updates, primarily painting in USN colors, 5"/25 replacing the 4.7" and 1.1" and .50cal AA in place of the pom-poms for compatibility, new radio antennae, the idea being to get them into service quickly until new ships are available. Condition is less important than having working battleships. Yes, there are tens of thousands of incompatible parts, fleet train issues and the ships need major work, all can be addressed after the North Carolinas and some South Dakotas are worked up and available.
A 1945 version would be a major rebuild similar to my model plus bulges, a raised bow, all 5" secondaries, modified and expanded superstructure, no boats, new masts, maybe even new main turrets with US 16"/45. Many changes would be internal or below the waterline - new wiring and generators, rearranged spaces, replaced engines, perhaps a bulbous bow a la the Iowas. This would not have happened, given the lack of need of them by that time, but it is interesting imagining.

 

[BlackBat242]

Here is one "forum alt-history" version of a US-modernized Nelson class - 9x2 5"/38 mounts, 6 octuple 2pdr pom-poms, 4x4 40mm Bofors, 16x1 20mm Oerlikon:

 

[Dilandu]

A 1945 version would be a major rebuild similar to my model plus bulges, a raised bow, all 5" secondaries, modified and expanded superstructure, no boats, new masts, maybe even new main turrets with US 16"/45. Many changes would be internal or below the waterline - new wiring and generators, rearranged spaces, replaced engines, perhaps a bulbous bow a la the Iowas. This would not have happened, given the lack of need of them by that time, but it is interesting imagining.

Royal Navy in late 1930s considered that a new 70.000 hp powerplant would allow to reach 25-26 knots without changing the hull forms.

 

[JoeCalPo]

I read of a concept where X turret is removed and the space and tonnage used for more engines. That part seems impractical, considering the relative locations, but it would allow for a considerable upgrade in AA, adding medium caliber guns. Just tossing another log on the discussion fire!

 

[Dilandu]

I read of a concept where X turret is removed and the space and tonnage used for more engines. That part seems impractical, considering the relative locations, but it would allow for a considerable upgrade in AA, adding medium caliber guns. Just tossing another log on the discussion fire!

Not make much sence. The existing machinery space is big enough; it's the boilers and turbines which are outdated early 1920s designs. Just replacing them with modern ones of the roughly same size would double the power on shafts.

 

[T. A. Gardner]

Here is one "forum alt-history" version of a US-modernized Nelson class - 9x2 5"/38 mounts, 6 octuple 2pdr pom-poms, 4x4 40mm Bofors, 16x1 20mm Oerlikon:


View attachment 713232

Some things I think the US would do differently:

The aft 5"/38 turret would not be placed. The 4 side 5"/38's would have the inner two elevated above the fore and aft ones and all would be on the main deck.

The crane on the port side would be gone.

If the ship were going to be used by the US, all of the 2 pdr pompoms would be replaced by quad 40mm Bofors mounts. The ship's boats and crane would be gone. Two additional quad 40mm Bofors would be installed in that space. Aft, a second 40mm Bofors would replace the aft 5" turret on an elevated platform.
All anchors and associated equipment with them except for two, one port and starboard, would be removed. Ventilation would be installed and all portholes would be welded over. Unseen, the ship's electrical system would be altered to 220/450 VAC, in part, with two additional diesel emergency generators installed. The torpedo room forward would have been subdivided for better watertightness.
More 20mm guns would be added.
All hatches below the 2nd deck would be welded up and modifications made for "up and over" movement in the ship. Escape trunks would be installed in the main spaces.

All radar and other electronics would be converted to US standards. Berthing and messing would be converted to US standards.

 

[Colonial-Marine]

I know there was a period of time after Pearl Harbor where the USN was quite desperate for any battleships they could get their hands on. Including trying to buy some of the old dreadnoughts from South American nations. Nelson and Rodney were in need of refit and upgrade work, especially the latter, but would the UK really be willing to trade/loan one of them even if Tirpitz was sunk at that early date? The UK was willing to loan HMS Royal Sovereign to the USSR, but that was an old ship that had received little modernization over the years. Her class of battleship was considered the most outdated in the Royal Navy.

Depending on how much of an upgrade is decided upon, it might not be until 1944 that the modernized battleship is ready for battle. I guess what events occur in this alternate war in Pacific will determine if she is seen as an unnecessary expense once ready, or an important asset to the fleet for the upcoming push towards Japan.

I believe the British drew up plans to add protection against diving shells to the belt armor scheme, so implementing that might be possible with all of the major work it would take to replace the ship's machinery and everything else. The 16" AP shells used by the Nelson class are commonly considered to have been too lightweight in hindsight. It's possible the USN's 16" Mark 5 AP shell could be adapted to those guns. The Mark 8 "super-heavy" AP shell isn't out of the question, but specifics of the shell handling system would determine that.

The British were informed the 5"/54 caliber gun wasn't really an option for them when they were looking for USN yards to modernize several aspects of the ship, but hypothetically it might not be entirely out of the question. Work on those guns and mountings was still being pursued and could have been made more urgent depending on how important the USN sees their need for battleships. Lighter AAA would be as many 40mm Bofors and 20mm Oerlikon as space permits, as was the trend with USN battleships. The internal torpedo tubes and torpedoes would probably be removed as those were seen as having very limited value. I'm sure those compartments in the ship could be used for something else. I wonder if it would be worth keeping a catapult on X turret for a OS2U Kingfisher or SC Seahawk.

As T.A. Gardner mentioned you'd need air conditioning for the climate, changes to berthing and mess halls to meet USN standards, upgrades to the electrical system. I think you're talking about a rebuild almost on-par with the work done on USS West Virginia. The end result would be pretty impressive however and a match for the USN (and RN) fast battleships in most areas other than speed.

In terms of utility, it might have been better if HMS Hood has somehow survived, with the (probably damaged) ship being loaned/traded to the US who would modernize and rebuild it for use in the Pacific. In such form she would be able to generally keep up with all of the USN's fast battleships and fleet carriers. Although I think the RN would have to be very lucky to take out both Bismarck and Tirpitz without at least one of their capital ships being sunk in return.

 

[T. A. Gardner]

I don't think the US was hurting that bad for battleships. By Midway--roughly 6 months after the start of the war--the US battleline in the Pacific had 7 operational battleships in the Pacific, a fairly sizable force.