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The KM changes their U-boat construction

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  • The Exorcist
    Going with mainly smaller boats served the KM in two ways -
    Those cheap little VIIs could be built in larger numbers and more cheaply.
    Smaller boats that can maneuver and dive quickly suited Doentz's tactics far better. He was enamored of daytime stalking and Nighttime attacks, on the surface. Big boats like the Japanese had were slow to dive and didn't score very well.

    I think the Germans had "cruiser" subs in WW1, and were disappointed by their performance... if I recall correctly.

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  • Mostlyharmless
    I suspect this idea fails due to geography. For example, the distance from Bremen to Singapore is 11995 nautical miles via the Cape (and almost certainly the English Channel). The USN fleet boats had approximately the same range as the Type IXC submarines, given by Wikipedia as 13,850 nm at 10 knots. A Gato could carry up to about 450 tons of fuel compared to around 250 tons for a Type IXC but they were bigger with length 95.0 m and beam 8.3 m compared to 76.76 m and 6.76 m. Thus the ranges were similar. Of course, life for a fleet boat's crew was notably more comfortable than for a Type IX's crew. The longest ranged I boats could possibly have just made the voyage as a range of 22,000 nm is given but these are big and rather vulnerable. The displacement of 2,920 tons surfaced and 4,150 tons submerged is almost twice that of a Gato and she still only has 18 torpedoes on board.

    However, what does become obvious from this idea is the advantages that the Axis powers would have gained if Egypt had fallen in 1940 because a Type IX operating from Italian East Africa can easily operate off Australia and all of Britain's eastern possessions.

    ps. However, there may be an argument for an earlier long range Type IXC. The Type IXA only carried 154 tons of fuel and could not even operate off the Cape of Good Hope. The Type IXB was the type being built in 1939 and carried around 200 tons.
    Last edited by Mostlyharmless; 08 Sep 16, 08:04.

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  • T. A. Gardner
    started a topic The KM changes their U-boat construction

    The KM changes their U-boat construction

    This “what-if” proposes that the KM recognizes that in a war, their commerce raiding strategy for U-boats needs to take a much wider area of operations right from the start. Historically, the KM built boats with the intent of commerce raiding in waters near Britain, their most likely opponent. These boats were the Type II to VII. Construction of larger, Atlantic capable boats didn’t start until very close to the war’s beginning leaving the Germans with limited ability to hunt outside the North Atlantic, North Sea, and Channel.
    Here, the Germans go for construction of three types of boats early:

    A Type VII for use as they historically did.
    A Type IX for use as they historically did.
    A Type “USN/IJN” boat. This is a much larger boat than the other two. It has a cruising range on the order of 15,000 + miles. These boats include air conditioning and have room for provisions to stay at sea much longer times and far further from Germany.
    To support them the KM prepositions a number of merchants in places where they can do so. Several of these merchants are in Japan when the war breaks out and proceed to remote Japanese islands, or elsewhere to resupply the U-boats. Surface raiders are trained to work with these boats in assisting them in finding targets and in keeping them resupplied.
    To further this, the KM enthusiastically adopts electronic sensor technology rather than a serious command structure with rigid control. Boats get seetakt radar early on. They have RDF on board on a folding or retractable mast. Improvements to ESM and radar are pursued aggressively. Countermeasures to enemy radar are sought as well.
    The result is, as the war widens the Germans are hunting merchant ships worldwide. The Allies have to escort everything and have ASW assets everywhere.

    So, when the war starts, the British / Commonwealth now have a few U-boats off India, Singapore, Australia, Canada, and elsewhere sniping at shipping. The RN has nowhere near the ASW assets to deal with such a far flung guerre de course of merchant raiding. Losses in places like the Indian Ocean rise precipitously as there are few, if any, escorts to be had. The two or three merchants with fuel and supplies sitting in Italian East Africa keep the boats operating.
    Areas like Singapore and French Indochina have their merchant shipping hit hard. The French and British having little or no ASW assets there to stop that. Even the Australians would be forced to begin building some ASW ships to protect their merchant traffic.
    This in turn would have forced Britain to put more resources into ASW than they did. That would detract from either the buildup of the RAF or army in turn.
    With a much wider plan of merchant raiding the U-boat force might well have made it too expensive for Britain to continue in the war. It certainly would have complicated things for them greatly.

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