Marine

Octopus inspires silent propulsion system for boats and subs

Octopus inspires silent propul...
Fraunhofer's prototype propulsion system
Fraunhofer's prototype propulsion system
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Fraunhofer's prototype propulsion system
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Fraunhofer's prototype propulsion system
The miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside
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The miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside

Along with their writhing tentacles, octopi and squid sport another interesting feature – they swim not by swishing a tail, but by expelling a jet of water. This allows them to move very quickly and quietly. Scientists from Germany’s Fraunhofer Institute for Manufacturing Engineering and Automation have now copied this system, in a propulsion system that could ultimately find use in boats, recreational watercraft, or submarines.

Known as the Octopus Siphon Actuator, the miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside. Initially, water is sucked in through an opening in each ball – just as a squid or octopus draws water into its mantle. Cables integrated into the balls then cause them to contract, rapidly expelling the water.

In the same way that the animals steer themselves by moving the funnel that the water comes out of, the Fraunhofer system can also be steered, using a motor to selectively point the balls in the desired direction(s).

The miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside
The miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside

The whole apparatus can be fabricated in one step, using a 3D printer. Production could reportedly be scaled up to the point of producing balls measuring two meters (6.6 ft) across. According to Fraunhofer, not only would a commercial version of the technology allow for fast and near-silent travel, but there would also be no danger of sea creatures being cut by propellers.

Interestingly enough, the German researchers aren’t the only people currently developing such systems. As part of the recent Google Science Fair, Texas teen Alex Spiride recently showed off his own bio-inspired Squid-Jet underwater vehicle.

Sources: Fraunhofer, Hack a Day

12 comments
Ricky Hall
Squid (squirt) power
Dekarate
this was part of the early thought process behind the development of the water jet engine, (jet skis, etc.) if I recall. Unfortunately, this will not develop sufficient power for planing boats. But if you want silent, slow cruising in sufficiently deep water - not the normal 3 attributes for recreational boating, have at it
Nelson
And what exactly is the advantage of a silent propulsion, other than allowing ballistic submarines not to be detected, and thus being able to start World War 3? Also, those marine life that have been able to survive because they could hear us coming now will be able to be killed.
Slowburn
re; Nelson Boomers are a retaliation platform. An ICBM first strike will be carried out by ground based missiles. Keeping the boomers hidden helps keep the peace. Years ago a whale was hit by a hydrofoil one of the noisiest boats imaginable. The postmortem on the whale showed that it was stone deaf on the critical frequencies from too much exposure to load noises. Also when you are surrounded by load noise makers all making similar noises Identifying the one that is closing in on you is difficult. In the long run quieter boats would be easier to hear.
Volodya Kotsev
Efficiency is much greater.
Don Duncan
Imagine a sub built non-metalic using this silent running. It could smuggle merchandise undetected.
Ian McIntosh
Whales and dolphins have been shown to suffer greatly from the noise of traditional prop systems. Silent or near silent ships will at least reduce this. Mind you I don't believe it is likely to be adopted commercially unless it can be demonstrated to be efficient as well.
Denis Klanac
Don Duncan, Shhhh!
Stephen N Russell
hows this compare to estd waterjet propulsion now used?? See no difference save the Navy funding for Sub & ship use alone
Gadgeteer
For biomimetic propulsion, I would prefer fishtail technology. Just as quiet, just as safe for wildlife and theoretically can scale up to much faster speeds. After all, the sailfish can exceed 60 mph and a slew of other species would leave the fastest submarines in the dust.