Project Taniwha was set up with the intention of advancing the underwater capabilities of humans. With such a goal in mind we set forth in early 2013 to develop our own human powered submarine. We started our design discussions in March 2013 with a fiberboard and aluminium mock-up of a hull. This evolved from the geometry of a 3 m long streamlined model, a solid of revolution tested in the David Taylor Model Basin (Model 4154) at Carderock Maryland; one of 24 models that provided experimental hydrodynamic data for post- WWII attack submarine design. This model was not optimum from a drag perspective. The 4154 low length to diameter ratio of 4 appealed to transport space constraints. A short hull would benefit maneuverability.
Work began in September 2013 with the construction of the hull. Our hull was cast in two halves. We have not permanently joined them together with resin. Instead we have used aluminium tabs and stainless steel screws to hold both halves in correct position. All systems within the hull are supported on a chassis. Such a modular design has enabled us easy access to internal systems for development, replacement and repair.
Propeller driven subs can be fast and reliable. However, there are drawbacks to propeller drive. There must be a gearbox between diver and propeller and this must incur a loss of sensitivity: the ability to detect contact between the propulsor and rigid objects (rocks) or to feel water currents. Swimmers and divers that wear fins can feel the water with each kick and also respond to it. Fins can produce bursts of speed, and can be used for steering. There is much to explore with finned propulsion and what better way to do this than to experience the finning as a man-fish within a finned sub.
We chose the commercially available Hobie Mirage Drive that is used for sit-on kayaks: a pair of reciprocating short fins directly driven by the feet. Drives were placed on the same aft longitudinal position, mimicking the New Zealand Leatherjacket (Parikascaber), that swims using undulatory motion of its dorsal and anal fins, while it steers with its tailfin.
The Taniwha was raced in Gosport, UK in the 2014 EISR. Details can be found in the “Races” section of the website.
In 2015, the Taniwha participated at the ISR event in Carderock Maryland, USA where they performed well above expectations. The team finished first in its class (non-propeller single pilot) reaching 3.56knots over a 100m long dragstrip narrowly missing a new record for a sub on this kind. The human powered 3m-long submarine is made of fiberglass and weighs 60kg. This historic win gave the propeller teams a real run for their money, proving that fin propulsion underwater is both reliable and fast – just as it is for fish.
Now in 2016 the new and improved Taniwha II is returning to Gosport for the 2016 EISR 6-16 July in an attempt to not just defend their title but also maybe even set a new world speed record for its class.