The Platypus

New Zealand’s Pioneer Submarine Boat

By Keith Gordon

New Zealand was gripped by gold fever after its discovery in Otago and West Coast rivers. Once the easily accessed gold was exhausted attention turned to dredging deeper rivers. On 14 December 1873 a crowd gathered on the jetty of New Zealands southern port of Dunedin to witness the Platypus committed to the deep.

Some had read of the Confederate submarine Hunley and her ill-fated attack on the Union warship but until now had little knowledge of such machines.

Designed to work in Otago goldfield rivers, the Platypus was an iron cylinder constructed of 3/8-inch plates (total length 35 ft/10.6m, diameter 7ft 2ins/2.2m.) A paddle or wheel box was fitted on each side and between an iron hatch covering allowing entrance into the hull.

An opening on the hull’s bottom was fitted with a water/airtight door to be opened when the vessel was on the bottom, providing access to the riverbed. Inside at the stern was an air reservoir to hold pressures of six atmospheres (90 psi). A tube passed through the reservoir which provided communication to both ends. The reservoir was connected to four air pumps fitted across midships and driven by motive power supplied by water wheels. The two wheels, driven by river current force, were connected to a main shaft.

A belt drove a countershaft attached to the air pumps which supplied fresh air through a tube connected to the surface. A rudder operated when submerged by two tiller ropes, or at surface by a deck handle. When submerged the wheel boxes would fill with water. The lower wheel parts were neutralised by water in the upper part of the boxes and to overcome this a pipe connected to the interior of the vessel supplied compressed air to expel water to within six inches of the box bottom. This allowed the wheels to operate easily.

Once on the river bed the bottom door could open and enable gold bearing riverbed to be scooped into sluicing apparatus fitted inside the hull. When submerged the sub was moved by a crab-winch. The sub would be floated clear of the bottom and winched ahead to a new position and then lowered with a brake.

The Platypus had its origins in 1872 when a Mr Nuttall arrived from Melbourne bringing plans and specifications for a ‘submarine boat apparatus’ designed by a Monsieur Villaine for, ‘digging and sluicing underwater’.

Reports of the invention created local interest and a prospectus for a New Zealand Rivers Gold Mining Company was issued, to use the patents taken out by Messer’s Villaine and Groundwater for the submarine boat.

However Nuttall failed to get the capital and the project was taken over by the New Zealand Submarine Gold Mining Co. The contract for construction went to the Dunedin Iron Works and the Platypus was delivered in August. Delays with final fittings postponed until 14 December the launch of the first submarine constructed in the Colony.

Floating buoyantly the little submarine was towed to a nearby jetty and readied for her first submerged trial but was prevented by difficulties. By 30 January 1874, the problems were resolved and Villaine and his son, Mr Douglas the engineer in charge of the construction, Mr Harvey a director, and four men to work the pumps entered the submarine through the entrance dome; this was then screwed in place sealing the eight men inside. The crew commenced pumping air to sustain life and emit water into both ends to submerge the sub. It took 1hr 50mins to reach the bottom however, as it was a shallow depth for the first test, part of the upper structure remained above water.

On bottoming, the lower door was to be opened and floats with flags sent to the surface. After two hours no signals had appeared and it was decided to signal them to surface. They had been submerged long enough to convince the most sceptical. For the first half hour the sub rose slowly until the tops of the paddle boxes were above water. A strong squall came up and in the rough water the sub became jammed under the counter of the lighter. Concern for the eight men heightened as at least two must keep pumping until the entrance hatch was above the surface; it was decided to tow the sub to shallower water so the hatch was above water. It was with some relief that the hatch fastenings were seen to move and the engineer emerged with his fellow divers.

The four pump crew looked exhausted as it was some 4hrs 20 mins since the crew first entered the Platypus. Mr Douglas reported the sub had been impeded in surfacing through leakage in the valves of the air pump and enough pressure could not be generated to expel the water. He had not opened the bottom hatch as he was concerned there would not be enough pressure to keep the water out. Although the trial was not termed a decided success, it was a long way from failure.

A further trial was carried out on 4 February and declared an unqualified success. The Platypus submerged and took 45 minutes to reach bottom; after a few minutes the bottom hatch was opened and there was no difficulty with keeping water out. Shells were collected off the bottom, also a fishing line and seabed mud. The bottom hatch was closed and there was no problem with expelling water to raise the sub from the bottom. The ascent took 14 minutes. The jubilant crew emerged hailing the dive a success. Mr Douglas, who remained on the surface for this dive, reported that provision had been made in case of foul air below to purify it by use of a quantity of limewater.

The New Zealand Submarine Gold Co. failed and the Platypus and its patent rights were put up for auction. They were purchased for $800 and the sub stripped of its fittings. The shell lay for many years by a Dunedin wharf until 1924 when, following a lecture on submarines at the Dunedin Officers Club, which recalled the building of the Platypus, a member bought the rusted remains. After cutting the hull into three sections he sent them off to central Otago. Today a section of the submarine is on display at the Middlemarch Museum.

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