Hello again - now the last part
@Krakatoa: Passive Sonar/Hydrophones (standard from ~ 1936)
3.3.1. Batch 1
The Dutch built Leipreachan-class perfectly satisfied every Thiarian requirement for a medium seagoing submarine, and was chosen as a template for series production while the prototype was still undergoing trials. Like the minelayers and cruiser subs, the Dutch basic design was modified in several ways to cater to specific Thiarian needs. They were lengthened, had slightly larger diameter pressure hulls and received flared clipper bows with some sheer forward and had the deadwood aft cut away to improve seakeeping and maneuverability. The hulls were fully welded, except over the main engine compartment where riveting was used for easier access. Displacement increased to 1.300/1.650 ts. The forward rudders were standardized with other Thiarian subs, as was the streamlined CT. ASDIC was part of the series package from the start. The number of torpedo tubes remained the same (four forward, two aft; 18 fish were carried), but a second 100mm gun was added. Initially only two 13mm MGs were provided for air defence. Engine power was increased to meet the ambitious requirement for 20 kts on the surface and 10 kts submerged; battery capacity was nearly doubled compared with the Leipreachans. Surface range remained 10.000 nm at 12 knots; these boats were not supposed to venture farther than the Capes or the equator (although some of them did during the war). Crash dive time officially was announced as 35 seconds, which sounds fair for their size, but was only achieved with full bunkers and increased as mission time progressed; the Thiarian navy never flooded empty bunkers with seawater because that did more damage than good. Maximum diving depth was an excellent 150 meters. The 1938 estimates contained the first four submarines, who received the names of marine mammals: LT Caisealoid (Cachalot), Mar Ron (Sealion), Deilf (Dolphin) and Piolotach (Pilot Whale). All were contracted to the CSCA yard, which had a long-established reputation of delivering quality in a short time, and lived up to it by building all four in under two years.
The 1939 estimates contained four more (LT Toithin (Porpoise), Miol Mhor (Blue Whale), Liopardron (Sea Leopard) and Mucmhara (Mereswine)), also all from CSCA and identical to the first four. The war programme stepped up production significantly; in 1940 and 1941, a total of 16 units were laid down, six in 1940 at CSCA (LT Beagron (Seal), Rorcual (Rorqual), Graonlannach (Harp Seal), Eilifint Mara (Elephant Seal), Droimeiteach (Razorback) and Dronnach (Humpback Whale)) and ten in 1941, four of them (LT Deilfliath (Grampus), Dugang (Dugong), Craindubh (Orca) and Narbhal (Narwhal) at the Boldisaire yard at Carriolar – which usually specialized in yachts and small craft – and the rest again at CSCA (LT Rosualt (Walrus), Bomhara (Manatee), Morshronnach (Bottlenose Whale), Sireinach (Sea Cow), Eite Chosach (Spotted Seal) and Banmhiol Mor (Beluga)). As these boats became available – CSCA achieved building times of 18 – 20 months during the war, Boldisaire needed half again that time – all the latest improvements were implemented. The 1939 boats already had ECM, IFF and passive radar when completed; they also received the newest wireless equipment.
The 1940 and 1941 boats had their 13mm machineguns replaced with a single 20mm gun upon completion; most of the others were retrofitted accordingly, although in some cases this took till mid-1944.
The class boat LT Caisealoid was employed as a testbed for a fully enclosed and watertight mount for a single 37mm cannon in late 1941 and early 1942; she had to land her forward 100mm gun to allow for the installation of the AA mount. Tests were eventually successful, and these mounts became standard for the second batch of the class in 1942. Caisealoid herself retained the 37mm mount for the rest of her career.
The 1941 boats were all completed with radars; the others enjoyed top priority for retrofits, and by early 1944, the whole class had radar. The 1941 boats also were the first ones who carried oxygene-powered torpedoes from the start; these were introduced in mid-1942 for the cruiser subs, and by late 1943 all Thiarian submarines except the minelayers had received them.
LT Toithin was fitted with a retractable 20mm twin instead of the fore 100mm twin after battle damage in late 1943; it was however decided not to refit any other Units of the class in this way.
The last boats of the class to be commissioned were the Boldisaire-built units of 1941; all four needed till early 1944 to become operational. Unlike their sisters, all of them were fitted with a twin 20mm mount aft of the CT in lieu of the single.
Four units – Liopardron, Rosualt, Morshronnach, and Banmhiol Mor – landed their aft 100mm gun in 1944 and replaced it with a second 20mm twin mount. This conversion was planned for the rest of the class as well, but in most cases could not be carried out for various reasons.
The 24 boats of the first batch of the Caisealoid-class bore the brunt of Thiarian submarine warfare in the Atlantic, which was quite a feat, because there were never more than ten of them operational at the same time. They were not enough to form as much as a single wolf pack, so their successes always were limited compared with what the Germans achieved, and no less than seven Caisealoid-class boats never scored a single kill at all. But by again and again hitting allied shipping in remote, unlikely spots, they contributed to the Thiarian strategy of pinning as many enemy escort forces to areas where they had little to do, thus reducing allied forces available to actively engage the Thiarians to a manageable size. In the end, allied production capacity prevailed, but postwar assessments came to the conclusion that the huge escort forces pinned to remote areas by a handful of Thiarian subs might have helped elsewhere to conclude the war several months earlier. Thirteen Batch 1 Caisealoids were lost during the war, including one that was set afire and burned out during the civil war. The survivors – LT Caisealoid, Toithin, Liopardron, Rorcual, Deilfliath, Craindubh and Rosualt – became allied prizes and were allocated to France and the Soviet Union. The French quickly scrapped their loot, but the Soviets used them operationally for several years, then for trials and training, and one actually escaped scrapping and was returned to Thiaria in 1970, along with the battlecruiser LT Caithreim, for refurbishment and exhibition. That boat, LT Toithin, incidentally was Thiaria’s most successful submarine of the Second World War with a net tally of 167.000 GRT. She remains permanently docked at the Thiarian submarine museum at An Trionaid and is the most popular exhibit there.
3.3.2. Batch 2
During 1940 and 1941, further orders for Caisealoid-class boats were placed; in their original shape, the subs looked pretty much identical to the first batch. They had the same size, displacement and performance. Internally, they were different however. A new type of more compact diesels with the same power allowed for the installation of larger batteries, increasing submerged range of 200 nm at 4 knots, which was an excellent figure for a traditional submersible. Improved flooding arrangements cut 5 seconds from their crash dive time regardless of how much fuel and stores they carried; in service, they only were good for the same 35 seconds as their predecessors, although they were indeed less affected by empty bunkers. Diving depth remained at 150 meters. All of the 12 units laid down in 1942 – six each at CSCA (LT Barracuda (Barracuda), Miolsiorc (White Shark), Colgan (Swordfish), Dorad (Dorado), Bradan (Sturgeon) and Rotha (Stingray)) and Boldisaire (LT Piorana (Piranha), Brathaire (Sea Devil), Casuir Siorc (Hammerhead), Maco (Mako Shark), Cearban (Blue Shark) and Liamhan (Basking Shark), respectively) – were delivered till September 1944, with building times varying from 15 months (Barracuda was commissioned in October 1943) to 22 months for Cearban. They might have been built even faster if not for the decision to fit them with two fully enclosed 37mm AA guns in lieu of their entire gun armament, which was made in November 1942 when they were still under construction; war experience at that point showed that the air threat had been badly underestimated prewar, while opportunities to use 100mm guns in a surface engagement had become scarce during 1942. The first three CSCA boats (Barracuda, Miolsiorc and Colgan) had both 37mm cannon on deck level.
All others had the forward one integrated into the CT in a hydrodynamically more advantageous way.
The 37mm mounts were quite complicated and had some teething problems, but CSCA solved them by late 1943, and from then on, they worked reliably. Since these boats also were all commissioned with a factory loadout of oxygene powered 559mm torpedoes, they managed to score some successes despite having to operate under constant pressure from the ever-increasing allied escort force. During 1943, twelve additional units were laid down, eight at CSCA (LT Reamora (Remora), Sciota (Skate), Laimhineach (Anglerfish), Tuinnin (Tuna), Cat Mara (Catfish), Eascann (Moray), Anglait (Monkfish) and Breac (Trout)) and four at Boldisaire (LT Curaman (Tench), Fiogach (Dogfish), Leathog (Plaice) and Alabard (Halibut)), to identical plans. Of these, only Reamora and Eascann were completed before the armistice. Tuininn, Cat Mara, Fiogach and Leathog were delivered afterwards, but not commissioned. LT Sabh Mara (Sawfish), Cnudan (Gurnard), Doingean (Bass), Greine Mara (Sunfish), Cimeara (Ghost Shark), Bumalo (Lizardfish) and six unnamed units were laid down in 1944, the first six at CSCA, the unnamed units at Boldisaire. Only the first two were launched, both after the war. The others were still in early stages of construction when the war ended; all were demolished on stocks to provide material for the completion of some of the 1943 units after the war. Of the eighteen completed units, only ten (all 1942 boats except Maco and Liamhan) saw operational service. Of these ten, only five managed to hit allied shipping; Piorana however racked up a tally of 70.000 GRT on a single mission in late 1943. Miolsiorc, Bradan, Brathaire, Dorad and Casuir Siorc were lost, the last three of them without having achieved anything. Rotha and Eascann were scuttled during the civil war, and Fiogach was set afire and burned out in dock. When the armistice was signed, Barracuda, Colgan, Piorana, Maco, Cearban, Liamhan, Reamora, Tuininn, Cat Mhara and Leathog were left. The first six were earmarked for service with the Thiarian co-belligerent forces against Japan, but only Barracuda and Maco saw actual service in the Pacific. Both were requisitioned and handed over to the USN as prizes when the war was over. The other eight remained in Thiaria and became part of the Nation’s much reduced postwar naval defense force. They were stripped of all gunnery between 1946 and 1948 and rerated as training vessels.
They spent most of their service providing sparring partners for Thiaria’s ASW forces in the following years. Cat Mhara was lost in an accident in 1950, but replaced by Cnudan, whose hull had not yet been broken up and was completed by 1954. By that time, Thiaria already had access to modern US sonar and electronics gear, and Cnudan became a prototype for the reconstruction of the whole fleet. They received modern active and passive sonars of domestic design (although with US help), a completely reworked periscope array and communications equipment, a US-sourced fire-control computer and radar, a snorkel, completely new batteries and electric motors and a redesigned bow; the latter modifications boasted their submerged speed by 50% to 15 kts. Surface speed fell to the same figure due to the installation of smaller, more economic diesels; surface range dropped to 8.000 nm because the size of bunkers was reduced. The rebuilds lasted from 1956 (Colgan) to 1959 (Tuirinn).
Although these boats would have reached the limit of their service life in about 1970, a replacement programme launched in 1966 came to naught after Thiaria’s swing to the left and her flirt with the Soviets; a Soviet offer to deliver new Foxtrot-class subs to replace them was rejected because these would not have been a real improvement. These developments ensured an exceptionally long service life for these subs; they were retired between 1982 (Barracuda) and 1989 (Tuirinn) without having been significantly refitted again.
3.4.1. Batch 1
Owing to an operational emphasis on mine warfare and a lack of torpedo-tube deployable mines, the Thiarians built more dedicated minelayer submarines before and during the Second World War than any other power. As the Meadail-Class was a very satisfying design, all further developments were based on it. The 1938 and 1939 estimates called for another four units per year, which differed from the original by having a fully welded hull with new, standardized forward diving planes and stronger internal structure for a diving depth of 100m. Speed and surface range were unchanged, but more efficient batteries increased underwater range to 100nm at 4 knots. Under the war programme, another eight boats were laid down in 1940 and 1941 (four per year represented the capacity limit of the CTS yard’s submarine facility). The changeover from riveted to welded hulls was deemed significantly enough for a new naming convention; like the French boats that had inspired them, the improved Meadails were named for gemstones. Their names were LT Pearla (Pearl), Criostal (Crystal), Corail (Coral) and Ghrianchloch (Quartz) in 1938, LT Smaragaid (Emerald), Agait (Agate), Aimitis (Amethyst) and Diamant (Diamond) in 1939; LT Saifir (Sapphire), Turcaid (Tourquoise), Ruibin (Ruby) and Omra (Amber) in 1940 and LT Topas (Topaze), Citrin (Citrine), Obsaidian (Obsidian) and Gairnead (Garnet) in 1941. As usual for the CTS yard, building times were relatively long, but improved as the war progressed; the first four needed an average of 30 months, which dropped to 26 for the 1939 and 1940 boats and 22 months for the 1941 group. When delivered, all had active and passive ASDIC.
All 1939 and later boats were already delivered with IFF, ECM and passive radar. Retrofit to the older boats was complete in early 1943.
The first unit of the class to receive radar was Turcaid, which was commissioned last of the 1940 group in May 1943. She also had a 20mm gun in lieu of the usual 13mm twin, and was field-converted to carry another 20mm on the upper deck late in 1943.
The 1941 group was mostly identical to Turcaid; by December 1943, all were in service. Refit of the earlier boats with radar and 20mm guns was underway pretty much throughout the war as they became available for R&R; at the time of the armistice, all were completed, Corail being the last one in July 1944. They operated successfully all around the South Atlantic Ocean; one of Criostal’s mines very nearly sunk the battleship HMS Resolution off Dakar in 1942, and their efforts made the ports of Sao Paulo and Rio de Janeiro virtually unaccessible during most of 1942 and 1943. As could be expected, losses were high; at the time of the armistice, only Corail, Aimitis, Saifir, Turcaid, Omra and Gairnead were left. The allies were not interested in them as prizes, and they remained in Thiarian hands, but by the time the Thiarian Navy was again allowed to operate submarines in 1948, torpedo-tube launched mines were available, and these boats were never re-commissioned. They were used for a long time as mooring pontoons or floating oil tanks. Four were scrapped during the 1960s, and the last two were scuttled in 1979 and 1983, respectively, as artificial reefs at the coast of the Eilean Deilf near Ogleidhras; they are popular diving sites to this day (if you can stand the temperature of the water).
3.4.2. Batch 2
Answering the navy’s call for much increased underwater endurance – which was particularly important for the minelayer fleet which was more affected by the ever increasing allied air threat than the subs operating in the open ocean – CSCA presented a linear upscale of the Pearla-class with a lengthened and widened pressure hull and nearly doubled battery capacity; the larger size also allowed for the addition of two mine tubes on either side, increasing mine loadout to 40. Surface speed dropped slightly to 15 knots, submerged speed remained at 9 knots, and surface range increased to 10.000 nm. A 20mm twin mount substituted the single mount of the first batch. CSCA kept up its building rhythm of four boats per year; LT Oinisc (Onyx), Resheoid (Moonstone), Turmailin (Tourmaline) and Opal (Opal) were laid down in 1942, LT Sead (Jade), Beiril (Beryl), Camail (Camelian) and Gaing (Jet) in 1943. When the Thiarian civil war commenced, only Oinisc and Turmailin were complete. Neither performed a minelaying mission before the armistice; during late 1944 and early 1945, CSCA also delivered LT Resheoid and Opal.
The other four units were cancelled shortly before the armistice so CTS could mass-produce the small Tuireann-Class coastal defence submarine, and broken up before launch. The four completed units remained in Thiarian hands after the war; between 1947 and 1950, their mine tubes and gun armament were removed and they were turned into conventional fleet submarines.
Opal and Resheoid were converted to testbeds for sonar and electronics development in 1953/4, but used only briefly in this role before they were retired in 1958 and partly broken up to be used as lifting cylinders for underwater salvage operations. Oinisc and Turmailin remained in use as training boats till 1957 and 1962, respectively. The former was converted to an underwater target in 1957 and used up in a live-fire exercise in 1964. Turmailin was hulked in 1963 and used as a stationary training unit at the Submarine school, where she remained in use till 1993. She was then handed over to the scientific museum at Clianmehail, where she was transferred via the Liathui river; she was carefully reconverted to her original minelayer configuration and remains on display to this day.
By mid-1943, the Thiarian submarine arm was operating virtually worldwide and possessed a suitable type mix for a coherent overseas strategy. The Thiarian surface fleet had so far performed well against anything the Allies threw at it, and Thiaria proper was still safe from enemy strategic bombing. But elsewhere in the world, the tide of war turned; Thiarias allies suffered crushing defeats at Stalingrad, Kursk and Rotuma during the first half of 1943, and the spirited attempt of the Axis to retake French North Africa faltered in the Battle of Bizerte, resulting in an allied counteroffensive that finally took Tunis in October 1943. The decimation of Japanese/Kokoan naval power and the loss of North Africa threatened to free allied naval assets which previously were earmarked for the Pacific and the Mediterranean. Allied – especially US – naval construction assumed ever more monstrous dimensions, and the Thiarian Navy acknowledged the possibility that they might have to defend the home islands much closer to their shores than expected at some point in the future – to which kind of warfare the current submarine fleet could contribute very little. To provide the ability to do so, the small coastal submarine, which had ungloriously been dumped from Thiarian naval planning in the mid-thirties, was unearthed again. The Naval Submarine Yard drew up a design for a 400-ton boat of compact dimensions with enhanced survivability against all kinds of ASW measures, which could operate in areas where the enemy enjoyed air and surface superiority. Like all Thiarian subs, it was double-hulled and of very sturdy construction, requiring a construction time of about 12 months. This was fast by Thiarian standards, but laughably slow by anyone else’s. The newest high-capacity batteries were installed to provide high underwater speed and endurance; 15 kts burst speed and 250 nm range at 5 knots were achieved. Above water propulsion and range was not neglected (as in the smaller German and Japanese boats with high underwater speed); the boats could reach 16 knots and had a range of 5.000 nm at 10 knots. Armament consisted of four bow torpedo tubes without reloads and a 37mm cannon in an enclosed turret, the same type that was installed on most Thiarian fleet submarines at that time. Crash dive time had been cut to 20 seconds. As might be expected, 500 tons was not quite enough for the total package; the final design displaced 550 tons on the surface and 650 tons submerged. Seakeeping in rough weather was no decisive factor in the design of these submarines; neither was habitability. In October 1943, the Thiarian Navy decided to quit construction of cruiser and minelayer submarines, devoting the Naval Submarine Yard and CTS to the construction of large numbers of the new coastal boats. Eight units at each yard were ordered that month, and work started immediately. They received the names of celtic deities and other mythical creatures: LT Tuireann, Cliona, Nuada, Eladha, Oghma, Brighid, Morrighan and Neimheadh (Naval Submarine Yard) and LT Rhiannon, Eithne, Niamh, Cian, Creidhne, Cethlenn, Manannon and Aine (CTS). By year’s end, all were laid down; the Naval submarine yard delivered the first unit (Cliona) in early August 1944, after ten months, which was the shortest building time for any Thiarian submarine during the war. Prior to the armistice, seven more were delivered (Tuireann, Nuada, Oghma, Morrighan, Rhiannon, Eithne and Cethlenn); the Naval Submarine Yard delivered the balance of the initial order (Eladha, Brighid and Neimheadh) after the armistice, while work on the CTS boats ceased during the war because the shipyard became a battlefield between rebellious naval personnel (supported by union workers) and fascist militiamen.
None of the boats completed the initial training cycle, and there were no operational sorties. As high-speed subs were of more interest to the allies than traditional fleet subs, all Tuireann-class boats had to be surrendered, while many much larger subs remained in Thiarian possession. Three each went to the USA and Great Britain, two to the Soviet Union, one to France and one to Brazil. Since contemporary German submarine technology was also in allied hands and far superior to Thiaria’s, these subs, though exhaustively tested, had no influence on postwar submarine development; all except one were scrapped in the 1950s. LT Nuada however was still afloat in 1990, when she was discovered in a wooden boat house in a small river estate in Latvia, where she lay since the late 1950s, rusty and forgotten; she was purchased by a private Thiarian company for a handful of dollars, refurbished and put on display at Sea World in An Thuaid, where she remains to this day. Of the 24 boats laid down in 1944 (Lugh, Tailtiu, Fodhla, Neith, Ciocal, Cenncroithi, Luchtaine, Tuan, Aengus, Nechtan, Airmidh, Banbha, Daghdla, Badhbh, Nemhain,Ecne, Danan, Emer, Deirdre, Eriu, Boann, Etain, Bebhinn and Mocha), none was completed. Sixteen more, for which no names were assigned, were scheduled to be laid down during 1944 as well, but were never begun.
All things considered, Thiaria’s submarine campaign made the best out of rather limited resources. Thiaria started the war with 25 submarines, eight of which were earmarked for training duty. Numbers were then built up quickly; including the pre-war boats, the Thiarian navy commissioned a total of 116 submarines between 1932 and 1944. Another sixty were begun, but never delivered. Although these numbers are dwarfed by Germany’s production and are not too far removed from Italy’s (the Italians ordered sixty subs in 1935 – 1939 and another 72 from 1940 to 1943), it has to be noted that Thiarian subs on the average were much larger than German or Italian ones; tonnage-wise, the Thiarians out-produced Italy nearly 3:1. Sixty Thiarian submarines were lost during the war, half of them to air attacks. With a tally of 237 enemy ships of all types totalling 1.280.000 GRT, they scored less than 10% of the German submarine arm, but on the other hand had to make do with only about 10% of Germany’s submarine fleet. Their main effect was the diversion of very substantial allied escort forces to backwater areas, particularly the Indian and eastern Pacific Oceans, which prevented the Allies from concentrating their overwhelming numerical superiority where it was needed during most of the war.