Carrying its own torpedo-loading derrick made the boat less dependent on a fully equipped tender or an ideal berth. The drawing also shows how the galley, stores, machinery, weapons, and accommodation were crowded into a very restricted internal space. A later non-reloadable aft tube offered a slim parting shot against a pursuer, although a single torpedo gave poor odds of hitting. A single pressure hull with external saddle tanks was comparatively quick and cheap to build and easier to inspect than a more complex double-hull arrangement. The tanks also broadened the working platform and improved stability for guns and other deck equipment.
Chapter · 29:30-33:03
Torpedo handling, cramped accommodation, and saddle tanks
The 1929 design drawing reveals a practical torpedo derrick, a tightly packed internal layout, and the construction logic of external saddle tanks.