Underwater 4WD chases world records

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

Words and pictures David Hancock

One of Australia’s most beloved vehicles is hoping to break a number of world records tomorrow when a group of divers and engineers drive a 40 series SWB Landcruiser nick-named “Mudcrab” across Darwin Harbour underwater.

Darwin harbour is home to saltwater crocodiles.

The cruiser was built in 1978 but has undergone an electric conversion. A crossing was attempted in 1983 when a similar vehicle got halfway across. After a trial run at Casuarina Beach this week and a solid dunking in a tank of water in Darwin, the team which converted the “Forty Shorty” is confident of completing the 7-kilometre trip, plunging to depths of 30 metres, in under 5 hours.

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Work on converting and waterproofing the vehicle took more than 6 months; scores of volunteers contributed hundreds of hours of their time, along with electrical conversion equipment.

The project is the brainchild of two engineers who grew up in Darwin: Finn Davy and Glen Summers. According to Glen, the failed 1983 attempt was folk law when he was at school and the duo was inspired by the audacity of the project. Back in 1983, the crew modified a normal Toyota diesel engine but the starter motor became waterlogged and failed.

The route, from Mandorah on the western side of Darwin Harbour, to Mindil Beach, is not without it’s hazards, the main one being two large gas pipelines that run from Timor Sea gas fields to plants deep into the harbour. Due to Federal legislation, the “Mudcrab” will have to be lifted over the pipelines which are in the deepest part of the route.

Men with dog
L to R: Taylor Smith, Finn Davy, Tommy Lawrence, Glen Summers, Luke Purdy (holding dog Aria), Mathew Mitchel – in the tank: Travis Lia.

According to Mathew Mitchel of Oceantec, a commercial diving business based in Darwin, who is in charge of the operation, the divers are not so concerned about marine predators such as crocodiles, but getting stuck on the seabed or trapped on a reef or rocky outcrops.

“The first task was to map out the route,” he said. “So we basically have a 3-D map of the harbour. It wasn’t that hard to map a route but we also had to do some confirmation dives and seabed surveys in a few areas, like where the gas pipes were buried.”

There will be two surface vessels, one carrying divers who will stay underwater for between 15 and 30 minutes depending on the depth, and another operating an ROV that films and monitors the vehicle. The car will be driven by a diver with guidance by the support vessel.

Darwinites are expecting a successful crossing and many are expected to be on Mindil Beach when the “Mudcrab” arrives early afternoon.

Spoiler Alert: Mission accomplished! Read how they did it, breaking 2 world records (and catching a couple of barramundi along the way).

The Ultramarine project – focussing on research and innovation in our marine environments – is supported by Minderoo Foundation.

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