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Well, if you take the best option off the table all you are left with is a bunch of minor tinkering of various cost for little overall result.And no you resident contrarians, scrapping and using the treaty tonnage to build a replacement carrier is not an option.
HMS Hermes (95) had IMO three flaws that I would like to address:
1) The huge destabilizing island and tripod mast
2) The inclusion of six 5.5" low angle guns (with FC directors on tripod mast)
3) The aft lift being exposed to the sea on three sides (was thus designed to enable aircraft to be moved from barge straight into hangar.
Here is Hermes at her launch.
You can see how high she was in the water before the island and other fittings were installeI suggest that reducing the island size, eliminating the tripod mast and anti-ship armament, along with enclosing the stern (if her keel and hull can take it) would make for a better ship. Hermes had wide elevators, and a good-sized rectangular hangar.
What other flaws would you like to address in the interwar period? And no you resident contrarians, scrapping and using the treaty tonnage to build a replacement carrier is not an option. Perhaps squaring off the bows, squaring the T-shape lifts, removing the aft rounddown, adding crash barriers and outriggers? We'll need to increase the avgas and magazine stores if we want a larger CAG.
Not bad ideas. The USN's 31 knot Independence class CVLs were about the same size of Hermes (11,000 tons standard displacement, approx 600 ft x 70ft), though at least three feet deeper in draught. At 25 knots Hermes is already faster than most of the RN battlefleet, though your engine improvement to over 30 knots does have merit for flight ops and running with KGV class battleships, other carriers, plus cruisers and fast escorts. A smaller engine does free up space and weight as well, as you suggest. I'd like to enclose the stern to allow for deeper draught. Let's cut the giant island down to size, keeping in mind that our plans for a larger CAG will require space for personnel. If we're keeping the big island, what about adding radar?The RN could have completely rebuilt Hermes if they so desired and if the treasury would have parted with the funding.
As with Renown and Warspite, Hermes' elderly machinery could have been replaced with modern machinery of less weight, but more power and efficiency. Use the space saved to add a larger ~30,000IG avgas stowage system and larger magazines.
Remove the obsolete HA guns, LA guns and FC systems and replace them with a new DP HA armament and modern FC (say 8 x 4in DP guns), more short range AA weapons. New lifts to take larger aircraft.
So we get a 27-28 knot carrier, with capacity for maybe 20 Albacore sized aircraft in her hangars, greater cruising range and better AA.
The RN could have completely rebuilt Hermes if they so desired and if the treasury would have parted with the funding.
Use the space saved to add a larger ~30,000IG avgas stowage system and larger magazines.
Agreed.Well, if you take the best option off the table all you are left with is a bunch of minor tinkering of various cost for little overall result.
The 5.5 in guns weigh around 14-15 tons each without shield, Shield weighs about 4.5 tons if 1 1/2 in thick. So pulling the six guns gets you just over 100 tons on a 10,000ton ship (13,000tns full load) Reduced load in the magazines and reduced crew may be just as important.
The ship already trimmed by the bow so adding flight deck there may not be a good option. Granted adding a crap load of weight aft may help things out.
Ship is on the slow side, I don't believe she ever got new boilers? so book speed might be subject to question? Or at least hard steaming for long periods of time should be avoided.
Basically you already have 1.5 liters in a 1 liter bottle and no matter what you do you aren't going to get much more in.
This could be a good project for the overseas yards. In 1938 the Singapore naval base opens with a complete dry dock facility. Earlier, in 1924 the Esquimalt Graving Dock opened. Both are capable of taking Hermes' 600 ft size. By the 1930s the Canadians are already building civilian and naval ships on both coasts, but I imagine BC could use the work. Taking an active carrier out of service in 1938 when all three future Axis nations are rattling their sabres is not wise, so unfortunately Singapore is out (though I'd still like Hermes to use the base post-1938), so it's either Canadian or Australian yards. As for finances, why not sell the ship to the RAN?Agreed.
One would have to balance the expected results with the costs, in both £ and shipyard time.
Also depends when you're contemplating this.
During the 1920s the Royal naval shipyards are busy, building HMS Eagle, Furious, Courageous and Glorious.
It took some digging through this excellent collection of ship plans, but here's HMS Hermes 95 blueprints. The boilers are positioned two bulkheads inward, but being directly below the hangar deck should make for "easy" access from above. The turbines may be deeper in the guts of the ship.In reverse, the boilers are usually below the water line, at least the parts under pressure, Ducting for the hot gases obviously go much higher. Some large ships have 3 or more decks above the boiler rooms, Large American carriers may have 5 or more counting the hanger and the flight deck. The boiler rooms on ships bigger than destroyers don't reach the side the side of the ship. at least one bulk head/compartment separates the boiler room from the hull side, sometimes several depending on torpedo protection scheme.
Yep, if you stripped her right down to the keel and started over you might get a carrier that could support 30 aircraft for about a day and half.
Bit of an exaggeration but the Hermes used 6 boilers and 2 shafts to get 40,000hp. The Indiependence used 4 boilers and 4 shafts to get 110,000hp. Changes in boilers from 1917-18 to even the late 30s was huge but you are not going to turn the Hermes into a 30 knot ship with anything less than nuclear propulsion and/or a total rebuild of the boiler, turbines and shafts.
BTW the 1942 plans for the Independence class were for 12 fighters, 9 dive bombers and 9 torpedo bombers with a fuel storage of 120,000 US gallons.
You can't change the boilers without either ripping off the flight deck or cutting large holes in it. Trying to change the Turbines is just as bad, just in a different area.
The cost/effort is not worth the result. The Battleship rebuilds were justified in that the naval treaties allowed reconstruction but not replacement. The Hermes was exempt from that. The early carriers were allowed to be replaced at any time.
There was a plan to take out the 5.5 in guns and the 4in AA guns and replace them with four twin 4 in mounts and a few 2pdr pom poms but it was never implemented. During the late 30s the British had a shortage of the twin 4 in mount and a shortage of the 2pdr pom pom guns. They wanted to fit more of them than they did but production didn't allow it.
The picture just posted by Admiral Beez shows part of the problem with the Hermes, She had a very fine bow, which limited space.
On the Independence class carriers the forward lift was where it was due the hanger and the hull shape. The flight deck ended short of the bow because they figured the hull would not support a flight deck out to or overhanging the bow. The upper deck of the cruiser hull also curved up at bow which meant without redesign/rebuild=delay they couldn't use the added under flight deck space for hanger space anyway. The Independence class was about 10% heavier than the Hermes and 10% buys a lot of improvements when you figure in some of the differences in construction like welding over riveting.
I like the speed, but I don't know if ~20 aircraft are possible. I've created some to scale pics below, before I saw the model pic with the forward hangar width reduction.I stated 27-28 knots in my OP which could be achieved on about 50k SHP; Hermes made 26.2 knots on trials with 42.9K shp. 30kIG of Avgas would support about 200 sorties, which with a ~20 aircraft complement seems sufficient. USS Enterprise flew less than 400 sorties at Midway.
We may need to square off the lifts like I've done above for the Fulmars (Length: 40 ft 2 in), otherwise the Skuas may be too long to fit on Hermes' two 36 by 36.6 feet lifts.I was thinking of something like 8 Albacores and 12 Skuas. It might be possible to move, one or both, lifts to forward/aft of the hangar space, to increase the hangar stowage.
Start with the cheap and fast mods. Add crash barrier, outriggers, flush stem to stern flight deck, replace anti ship guns with AA, add radar when available. Hermes greatest improvement can be in the aircraft she is given, if Hermes lasts long enough, folding Martlets.There is no doubt that the Hermes could have been "improved". What is in doubt is how much and more importantly, at what cost.
IDK, but by the end of 1941 Courageous, Glorious and Ark Royal have been sunk and the new Illustrious and Formidable crippled and undergoing repairs in the USA. Until these latter two AFD carriers re-enter service in Feb 1942 HMS Hermes is one of only five RN fleet carriers (Indomitable, Victorious and Furious and Eagle). I think an updated Hermes could serve in front line roles into 1944.Would the Hermes have lived out her last years as an aircraft ferry and training carrier if the the British had not lost the Courageous and Glorious so quickly and to so little purpose?
At that point we might as well do a Langley and convert Hermes to a seaplane tender. Something like HMAS Albatross that entered service in 1929.shave 851 tons off its displacement below 10,000 tons and thus not an aircraft carrier under the treaty system