Why would you think of replacing the 15"MKI its both illegal under the treaties and by far the best bit of the QE/R class if you can change it you should build new ships!!!!!!Royal Navy Plan 1930 With Lots of Money Available Because Handwavium. *Admiralty 3-drums produce enough steam each for 20k shp.
Centurion - scrapped. YES, but why the only one!
Iron Duke - Q turret removed, 4 Admiralty 3-drum boilers & geared turbines fitted, BL 14" Mark VIIs, QF 4" DP & light AA, bow extension a la RM superdreadnoughts.
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Queen Elizabeth - lose casemate guns & magazines, develop 15"/50cal main gun with high elevation, fit 6 Admiralty 3-drum boilers & geared turbines, QF 4" AA and light AA.
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Revenge - scrap all but turrets and nameplate, build proto-Vanguard with 15"/50s, 8 Admiralty 3-drum boilers, geared turbines and lots of AA.
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Nelson - Remove 6" guns, replace with more AA, 6 Admiralty 3-drum boilers & geared turbines for 120,000shp.
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Hood - Extend fo'c'sle to around B barbette, new superstructure, fit 15"/50s, QF 4" AA, light AA, 12 Admiralty 3-drum boilers & geared turbines for 240,000shp.
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Renown - New superstructure, fit 15"/50s, QF 4" AA, light AA, 10 Admiralty 3-drum boilers & geared turbines for 200,000shp.
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Tiger - Remove Q turret, fit 10 Admiralty 3-drum boilers & geared turbines for 200,000shp, remove casemate guns & magazines, replace with HA DP QF 4" and light AA.
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Leopard - build as per Tiger using spare 13.5"s from scrapped dreadnoughts and refits.
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Courageous - hurricane bow, 6 Admiralty 3-drum boilers & geared turbines for 120,000shp.
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Adventurous - build as per the above.
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You have 23 Rebuilds (@1/3 cost of new ship minimum) and 10 new ships.....
For this budget I should be able to buy 7 new Lion class and refit Hood and then build 10 new CVs for a RN, (note that your rebuild will be more than 1/3 more like 1/2 to 2/3 if you want new everything so this is a worse case below, 1/2 would get you 10 new Lions?)
7 Lions far more powerful than anything you have after a rebuild
Hood after full rebuild just about ok to second a Lion
R&R fast to hunt PBs and cruisers
N&R +5 QE slow escort and bombardment force with minimal refits, add any of the 5 Rs you still want as well
10 new CVs
3 C,G&F as training & transport ships with any of the others older ship you want to man.