Treaty Cruiser Design Challenge

Looks like I beat Shiggy to the punch

de Villers-class, Marine Nationale
During our own time line, France had embraced the Treaty Cruiser as a way to gain parity with the other major naval powers despite her lower allocated ratio for capital ships, but had desisted from designing purpose built commerce raiders under the Washington Naval Treaty provisions chiefly to not upset Great Britain, which at this time considered strategic bombing to be the greatest threat to a civilized nation, and ranked the large and modern French bomber force as its most severe danger. At this time, a war between Great Britain and the United States, or between Great Britain and France was not out of the question. Thus France adhered strictly to the treaty provisions and built fast and well armed 8” gun cruisers to the best of its abilities. As soon as the design for the Duquesne-class was finalized, however, it became apparent that other countries had not adhered as strictly to the treaty provisions, specially Italy which had apparently achieved excellent speed and protection on its Trento-class cruisers, which of course, were later found to breach the treaty limits.
For this scenario, I’ve chosen to design and draw a dedicated raider in place of the Suffren-class cruisers, which would take advantage not only of liberal interpretation of the treaty provisions, but also of an uncommon arrangement to configure a small but well protected citadel in order to save weight, all the while still adhering to the 10,160 metric ton limit.

Springsharp report here: https://pastebin.com/5D0ckMSu
Note that the numbers will not necessarily coincide due to both adjustments made according to treaty provisions and due to number fudging according to my experience with springsharp, which is rather conservative in its speed and space powerplant space calculations for fast ships.

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The STCN has submitted a design that takes advantage of fuel not being counted into the treaty limit, thus presenting a short range on paper that can be doubled in overload condition while sortieing. Stores, drinking and boiler feed water are understated to a great degree. Ammunition for all guns is underrepresented from the desired number, but space is allocated for 50% more than the stated amount.

This ship is configured as a raider, with enough speed to outrun ships larger than her (HMS Hood, 32 knots) and enough firepower to overpower likely escorts like Light Cruisers and Armed Merchant Cruisers, for which she carries a typical cruiser battery of eight 203mm Model 1924 guns, but in two turrets only to economize on space. These turrets are divided in half by a 20mm bulkhead and have pairs of guns sleeved together like in other later French warships. The battery and main director all face aft in order to maximize firepower against pursuers. There is an auxiliary main battery director facing forward over the secondary battery director, atop the fore tower. The secondary battery consists of twelve 138.6 mm Model 1927 guns (40kg shell, slightly heavier than British and Japanese 5.5” guns) in five turrets, concentrating firepower forward and broadside, which I consider enough to overcome contemporary Light Cruisers. All the turrets are armoured and are placed on barbettes, and the fore turret is divided like on the main battery turrets. Anti Aircraft armament consists of six director-controlled single 100mm Model 1927 guns on shields and six 37mm Model 1925 semi-automatic guns. The ship also carries six 550mm 23DT torpedoes in two triple mounts disposed far back on the stern with no reloads, to be used as a defensive measure against pursuers or to sink particularly tough prey.

The ship has been configured with extensive aviation facilities on the bow, with a catapult, collapsible crane and space for three aircraft in an enclosed hangar below decks. When commissioned, de Villers carried three CAMS 37/2 flying boats which were intended to expand the cruiser’s reconnaissance radius.

The powerplant consists of nine Guyot boilers disposed in three adjacent boiler rooms feeding four Rateau-Bretagne SR geared turbines for an output of 100,000 hp on four shafts, giving about 34.5 knots on trials. Unitized machinery has not been adopted in order to save space.

Economies found in the battery arrangement and liberal interpretation of treaty disposition has enabled the provision of an extensive protection scheme for the ship’s vitals. The main belt protecting the vitals consists of 65mm armour at its thickest point, tapering down to 50mm below the waterline, and inclined 12° to the exterior. It is 2m tall over magazines and 3.5m tall over machinery spaces. Armour is extended to the bow by a 40mm belt 2m tall which has the purpose of preventing mission-impairing damage by destroyer shell. Horizontal protection is prioritized for long range engagements, and a 50mm deck tops off the citadel, above the magazines and the machinery spaces. The gaps are covered by 50mm bulkheads. Rudder machinery is covered by a box 40mm thick. The conning tower forward is protected by 70mm front armour, 60mm sides, 50mm rear and a 50 mm roof. The main battery turrets have 65mm faces, 50mm sides, 40mm roof and rear and sit on 65mm barbettes. The secondary turrets have 45mm faces and barbettes and 20mm splinter protection on sides, roof and rear. The 100mm guns are protected by 20mm shields.

First of class Berthe de Villers was laid down at the Arsenal de Brest in October of 1927, launched in June 1928 and commissioned in January 1931. After shakedown period she was assigned to Cochinchina, based on the port of Saigon.
The second ship in the class, Benjamin Jaurès, was laid down at the Arsenal de Lorient in January of 1928, launched in August 1928 and commissioned in January 1931. She was based at Tamatave for most of her career.

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Benjamin Jaurès went back to France for refit in 1937, replacing her six 37mm Model 1925 singles for six twin CAIL Model 1933, supported by rangefinders, and also added six triple and four twin 13.2mm Model 1929 machine guns. The 100mm Model 1927 single mounts were replaced by 100mm Model 1930 twin mounts for a total of 12 guns. Her aircraft were replaced by two Loire 130 reconnaissance and two Bernard H 110 fighters. The start of the war found her in Algeria, where she immediately sortied to hunt for German raiders. After the armistice she stayed at Toulon and was scuttled with the rest of the fleet in 1942.
Berthe de Villers received no significant upgrades save for rangefinders for the 37mm battery and replacing her aircraft for Loire 130. The war found her on drydock in Saigon and she was unable to reach Europe before the armistice. She briefly fought Japanese forces during their invasion of Indochina, and during the second invasion on July 1941, the cruiser’s crew mutinied and took her to internment in the Philippines, refusing to surrender to the Japanese.
Then once war erupted in the Pacific, she joined the allied naval command and engaged in the fighting in the Java sea. As reinforcements took over, she sailed to San Francisco where she was refitted at the Mare Island Navy Yard in late 1942. She received SG and SK search radar, four 1.1” Mark 1 quad mounts in place of all the 37mm guns and added eight 20mm Mark 2 guns on deck. She exchanged her aircraft, now impossible to maintain, for three SOC Seagulls and returned to service escorting Australia-bound convoys. She then escorted convoys during the Solomon Islands campaign and saw action at the Battle of the Santa Cruz islands receiving only near-misses by aerial bombs. She finally saw action at the Battle of Kolombangara, where she was missed by torpedoes and pursued the Japanese destroyers but was ordered to retreat and escort the damaged ST. LOUIS and HONOLULU.
Now worn out and barely able to do 30 knots, de Villers was deemed useful enough to herd Task Group 77.4 during the Philippines campaign. As Kurita’s center force found Taffy 3 and engaged, de Villers, currently with Taffy 1 and poised for shore bombardment, quickly set course NNW and loaded APC shell. As she appeared from within JOHNSTON’s smokescreen, the cruiser positioned herself to launch torpedoes at maximum range and then reversed south to bring her main guns to bear on the leading cruiser squadron flagship, Kumano. The attention of the IJN force quickly changed from the retreating Jeep Carriers to the defiant cruiser. de Villers quickly found the range but was soon bracketed by multi-coloured splashes from Japanese shells, her secondary batteries coming to bear on targets along their firing arcs. This distraction was used by HOEL, HEERMANN and SAMUEL B. ROBERTS to line up for successful torpedo runs on the IJN line. The cruiser’s foremost 203mm gun turret received a direct hit and half of its guns were disabled, the gunhouse division working as intended, regardless of the horrible casualties inflicted. Soon the Escort Carriers opened up with their own single 5”/38s and started scoring hits too, as scrambled aircraft attacked with whatever munitions they had (or didn’t have) available.

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The ferocity of the USN escort attack threw the Japanese forces into disarray, and numerous torpedo hits were scored, nevertheless de Villers had received numerous hits and was losing power. Emerging out of a rain squall at 0920, the cruiser was found by heavy calibre fire which detonated her aftmost magazine, tearing the stern off. The ship continued to float, occasionally firing from the remaining main turret and the secondaries for 20 minutes before the order to abandon ship was given. She sank 40 minutes later with 418 survivors.

Of course, your feedback and comments are very welcome!

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