War has always been a terrible business and the First World War brought its own terror with the mechanisation and industrialisation of warfare. War is also a catalyst of innovation; in the supercharged atmosphere of impending doom, the pace of innovation is accelerated as the pressure to find a competitive edge increases exponentially.
The First World War was dubbed “The War to end all Wars” and the Treaty of Versailles was an attempt to ensure nothing like this war would happen again. But all it did was to provide a catalyst for innovation in weapons and warfare.
Up to WW1 Great Britain had the largest navy, the Kaiser wanted to match and beat the Royal Navy. This led to a pre-war arms race, mostly consisting of supersizing boats with the gargantuan resource-intensive “Super Dreadnaught” class being the pinnacle of this design.
“German naval forces will be limited to 15,000 men, 6 battleships, (no more than 10,000 tons displacement each), 6 cruisers (no more than 6,000 tons displacement each), 12 destroyers (no more than 800 tons displacement each) and 12 torpedo boats (no more than 200 tons displacement each). No submarines are to be included.”
The Treaty of Versailles as it pertained to naval restrictions.
The Treaty of Versailles assumed Naval developments would be more of the same and therefore expressly limited the size of ships that the German navy could develop. Innovation requires focus and the conditions of the Treaty formed one component of a triangle of constraining forces that led to an astonishing new Naval class: in this case it was weight.
The Germans invaded Poland with the now famous and then highly innovative Blitzkrieg style of offensive, comprising of fast moving troops backed up by fast moving artillery, tanks and with superior air power. The innovative Blitzkrieg warfare extended to sea power as well and led to a demand for fast moving Naval attack craft. The second component was therefore the need for speed.
The final and third component was the geography and weather of the North Sea. Just as Germans’ land-based machines were designed to operate in the terrain of Northern Europe, this new craft had to operate effectively in the tough conditions of the North Sea, English Channel and Western Approaches.
Speedboats of the era could achieve significant speeds, but their short planing hulls which skimmed over the surface lost their advantage in all but the calmest of waters. Although they were light, they were relatively small and the weight of effective armaments tended to neutralise their speed advantage. In addition to this, they threw out an iridescent “rooster tail” from their stern at high speeds which at night was a dead giveaway of their position.
Conventional “displacement” craft could deal with the seaways and could carry sufficient armaments to be a menace, but could not provide enough speed for the requirements of Bliztkrieg, a feature of displacement vessels is that they are relatively slow.
Nonetheless, in 1928 the German navel command was drawn to Oheka II, a highly innovative luxury motor yacht featuring a round-bottomed, displacement hull built in 1927 by the German boatyard Lürssen for Otto Herman Kahn. Her hull was 22.5m long, and she displaced only 22.5 tons, significantly below the 200 ton torpedo boat limit of the Treaty of Versailles. She was the world’s fastest boat in her class, reaching a top speed of 34 knots.
There were three key design features that Lürssen’s deployed in Oheka II which helped this displacement vessel achieve these impressive speed and which would form the basis of a fast attack craft that subverted the “Maginot Line mentality” of the Treaty of Versailles:
- She was powered by three engines, each delivering 550hp to its own propellor and this power helped her deal with the tough seas in which she operated.
- Her hull was light for its length, being constructed of wood planks over an alloy frame.
- Finally, hydrodynamic lift was added at the stern by flattening the hull towards the stern, thus overcoming the tendency of the rear end of round-bottomed hulls to inefficiently “squat” in the water at speed.
Initial prototypes of an armed version of Oheka II formed the basis of the Kriegsmarine’s Schnelleboot. Initially two torpedo tubes were added to the topsides of the bow and improved frontal bouyancy was achieved by way of a pronounced knuckle in the bows.
But this wasn’t all. By extensive study of hydrodynamics, the engineers introduced another feature which would help deliver even more speed while reducing the giveaway rooster tail: the “Lürssen Effekt” rudders.
These skeg-like small rudders were mounted port and starboard of the main rudder and could be angled outboard to 30 degrees. At high speed, these rudders generated what became known as the “Lürssen Effekt," where the angled “rudders” drew a ventilation air pocket slightly behind the three 4ft propellors, increasing their efficiency, reducing the stern rooster tail and keeping the boat at a nearly horizontal attitude.
During the war the Schnelleboot (or E-boat as the Allies called them) underwent the kind of incremental improvements one would expect. Engines were increased in power to 3000hp each, both armoury and armour was improved, the latter most noticeably with the introduction of an armoured wheelhouse known as the Panzer Kalotte.
Ultimately though this marvel of naval technical mastery was doomed. Over-engineered, the exotic materials in the alloy frames and the engines became impossible to obtain towards the end of the war. The Schnelleboot, the fastest vessel afloat during the war, was superceded by missiles. Although capable of speeds of over 40knots, impressive even by today’s standards, the Schnelleboot was never as effective in operation as its fearsome reputation suggests*.
By D-Day it was all over for the Schnelleboot and impressive as these innovations were, the form factor itself was a blind alley. But the Schnelleboot showed that it’s not possible to legislate against innovation. The need to create, to produce a tool for a given job or task runs deep in the human psyche and we’ll always find loopholes through laws that attempt to stifle. Indeed it’s the creation of restrictive laws that can be a fuel for innovation.
*the most well known Schnelleboot action was recorded at Slapton Sands during a D-day landing rehearsal. S130 was involved in that action. Post-war she served in the Navy’s “Baltic Fisheries Protection Fleet” skippered by Sir John Harvey Jones. She was handed back to the Bundesmarine in the 50’s and was in continuous service in various guises until 1990. She is now being restored by the Wheatcroft collection www.s130.co.uk