Here's a missing baby for the North Sea, Norway, the Baltic and the Med -The Raumboot (R-boot)
The German R-boats were pressed in to service as minelayers and convoy escorts. Although they received increasingly powerful diesels they could rarely manage much more than half the maximum speed of an S-boat. An R-boat is shown off the Norwegian coast, where the Germans ran so many convoys that they constructed a purpose-built convoy escort based on the R-boat design. By 1944 R-boats bristled with guns, carrying a 37-mm (1.45-in) cannon and up to six 20-mm mounts. Many were fitted with Voith Schneider propellers, which increased manoeuvrability at the expense of some speed. The R-boats were originally 60-ton craft armed with a couple of 20-mm cannon plus depth charges or mines, as appropriate. From R17 on they grew to S-boat size, and mounted an increased armament- necessary on the vital Norwegian iron ore route.
Raumen is the German verb 'to clear or 'to remove', hence the Raumboot or R-boat type of coastal minesweeper. These craft were of such a useful size, however, that they also did duty as minelayers and, suitably rearmed, as escorts to convoys, in which guise they were involved in frequent brushes with British craft.
The original group, R1-16, was constructed in the early 1930s. Like the S-boats, they were built of wood on metal framing with round bilges. They were, however, of only 60-ton displacement and 26-m (85.3-ft) length. Propulsion was by twin-screw diesels for a modest 17 kts although one unit, R8, was fitted with Voith-Schnider cycloidal propellers, which made for great manoeuvrability at the cost of some speed. This experiment was deemed successful, and over 100 R-boats were eventually so fitted.
From R17 onwards dimensions were very similar to those of the S-boats, though with extra beam, and increased draught by virtue of their greater displacement. Even with progressively improved diesels, the average R-boat never much exceeded 20 kts and, when not actually involved in the minesweeping for which the type had been designed, was employed defensively. The exceptions were the dozen so-called GR-Boote (G for Geleit, or escort), R301-312, built to a stretched 41-m (134.5-ft) design displacing 175 tons. They had triplescrew propulsion for 24 kts and were fitted with a pair of torpedoes. Though used in something like the role for which the British employed MGBs, their firepower was little enhanced, and 88 more projected craft were cancelled.
Their construction did suggest the need for a true multi-purpose escort for the many coastal convoys that the Germans ran around North European waters, The result was the hybrid, steel-built MZ-Boot design (Mz for Mehrzweck, or multi-purpose) which, while having a heavy surface armament including two 88-mm (3.46-in) guns and two torpedo tubes, were of only single-shaft propulsion. Only Mzl was ever completed, not proving sufficiently satisfactory to warrant further priority being given for completion of the remaining 11.
Raumboots constructed were listed up to R-448 (or 448 built - though not all were launched).
R-266 (With R 407 in the BG)
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Topic: Raumboots, NOT S-Boots on Friday (Read 18086 times)
