Type X (XB) U-boats
were a special type of German submarine
). Although intended as long-range mine-layers, they were later used as long-range cargo transports, a task they shared with the Type IXD
and Italian Romolo-class submarines
The Type X was originally designed specifically to accommodate the newly developed Schachtmine A (SMA) moored naval mine
. The initial design provided dry storage for the mines, which needed their detonators to be individually adjusted before launch; this submarine was projected to have displaced up to 2,500 tons. A further variant, the Type XA was projected, which would have supplemented the main mine chamber with extra mine shafts in the saddle tanks. Neither type entered production.
A total of eight Type XB boats were produced, which replaced the mine chamber of the projected Type XA with six vertical wet storage shafts in the forward section of the hull. Up to 18 mines could be carried in these shafts, with an additional 48 mines in a series of 12 shafts set into the saddle tanks on each side. They only had two torpedo tubes, both at the stern. When used as cargo-carrying submarines they carried freight containers in the mine shafts (or had the freight containers welded on top of the lateral shafts, preventing their use for mines).
The first Type XB was launched in May 1941. At 2,710 tons submerged and fully loaded, they were the largest German U-boats ever built, and they had to... Read More