Student Drone Flies, Submerges

August 5, 2025 by Al Williams 8 Comments

Admit it. You’d get through boring classes in school by daydreaming of cool things you’d like to build. If you were like us, some of them were practical, but some of them were flights of fancy. Did you ever think of an airplane that could dive under the water? We did. So did some students at Aalborg University. The difference is they built theirs. Watch it do its thing in the video below.

As far as we can tell, the drone utilizes variable-pitch props to generate lift in the air and downward thrust in water. In addition to the direction of the thrust, water operations require a lower pitch to minimize drag. We’d be interested in seeing how it is all waterproofed, and we’re unsure how deep the device can go. No word on battery life either. From the video, we aren’t sure how maneuverable it is while submerged, but it does seem to have some control. It wouldn’t be hard to add a lateral thruster to improve underwater operations.

This isn’t the first vehicle of its kind (discounting fictional versions). Researchers at Rutgers created something similar in 2015, and we’ve seen other demonstrations, but this is still very well done, especially for a student project.

We did see a submersible drone built using parts from a flying drone. Cool, but not quite the same.

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Forget Propellers, Embrace Tentacle-based Locomotion

April 9, 2025 by Donald Papp 25 Comments

Underwater robots face many challenges, not least of which is how to move around. ZodiAq is a prototype underwater soft robot (link is to research paper) that takes an unusual approach to this problem: multiple flexible appendages. The result is a pretty unconventional-looking device that can not only get around effectively, but can do so without disturbing marine life.

ZodiAq sports a soft flexible appendage from each of its twelve faces, but they aren’t articulated like you might think. Despite this, the device can crawl and swim.

With movement inspired by bacterial flagella, ZodiAq moves in an unusual but highly controllable way.

Each soft appendage is connected to a motor, which rotates the attached appendage. This low-frequency but high-torque rotation, combined with the fact that each appendage has a 45° bend to it, has each acting as a rotor. Rotation of the appendages acts on the surrounding fluid, generating thrust. When used together in the right way, these appendages allow the unit to move in a perfectly controllable manner.

This locomotion method is directly inspired by the swimming gait of bacterial flagella, which the paper mentions are regarded as the only example of a biological “wheel”.

How fast can it go? The prototype covers a distance of two body lengths every fifteen seconds. True, it’s no speed demon compared to a propeller, but it doesn’t disturb marine life or environments as it moves around. This method of movement has a lot going for it. It’s adaptable and doesn’t use all twelve appendages at once; so there’s redundancy built in. If some get damaged or go missing, it can still move, just slower.

ZodiAq‘s design strikes us as a very accessible concept, should any aspiring marine robot hackers wish to give it a shot. We’ve seen other highly innovative and beautiful underwater designs as well, like body-length undulating fins and articulated soft arms.

We do notice that since it lacks a “front” — it might be a challenge to decide how to mount something like a camera. If you have any ideas, share them in the comments.

Undersea Cable Repair

July 30, 2024 by Dan Maloney 6 Comments

The bottom of the sea is a mysterious and inaccessible place, and anything unfortunate enough to slip beneath the waves and into the briny depths might as well be on the Moon. But the bottom of the sea really isn’t all that far away. The average depth of the ocean is only about 3,600 meters, and even at its deepest, the bottom is only about 10 kilometers away, a distance almost anyone could walk in a couple of hours.

Of course, the problem is that the walk would be straight down into one of the most inhospitable environments our planet has to offer. Despite its harshness, that environment is home to hundreds of undersea cables, all of which are subject to wear and tear through accidents and natural causes. Fixing broken undersea cables quickly and efficiently is a highly specialized field, one that takes a lot of interesting engineering and some clever hacks to pull off.

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Solving Cold Cases With Hacked Together Gear

June 28, 2024 by Tom Nardi 12 Comments

People go missing without a trace far more commonly than any of us would like to think about. Of course the authorities will conduct a search, but even assuming they have the equipment and personnel necessary, the odds are often stacked against them. A few weeks go by, then months, and eventually there’s yet another “cold case” on the books and a family is left desperate for closure.

But occasionally a small team or an individual, if determined enough, can solve such a case even when the authorities have failed. Some of these people, such as [Antti Suanto] and his brother, have even managed to close the books on multiple missing person cases. In an incredibly engrossing series of blog posts, [Antti] describes how he hacked together a pair of remotely operated vehicles to help search for and ultimately identify sunken cars.

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A Survey Of Long-Term Waterproofing Options

March 27, 2023 by Matthew Carlson 27 Comments

When it comes to placing a project underwater, the easy way out is to just stick it in some sort of waterproof container, cover it with hot glue, and call it a day. But when you need to keep water out for several years, things get significantly harder. Luckily, [Patricia Beddows] and [Edward Mallon] from the Cave Pearl Project have written up their years of experience waterproofing data loggers for long-term deployment, making the process easier for the rest of us.

It starts with the actual board itself. Many SMD boards have at least some flux left over from the assembly process, which the duo notes has a tendency to pull water in under components. So the first step is to clean them thoroughly with an ultrasonic cleaner or toothbrush, though some parts such as RTCs, MEMs, or pressure sensors need to be handled with significant care.

Actual waterproofing starts with a coating like 422-B or nail polish which each have pros and cons. [Patricia] and [Edward] often apply coatings to PCBs even if they plan to otherwise seal it as it offers a final line of defense. The cut edges of PCBs need to be protected so that water can’t seep between layers, though care needs to be made for connectors like SD cards.

Encapsulation with a variety of materials such as hot glue, heat shrink tubing, superglue and baking soda, silicone rubber, liquid epoxy, paste epoxy (like J-B Weld), or even wax are all commented on. The biggest problem is that a material can be waterproof but not water vapor proof. This means that condensation can build up inside a housing. Temperature swings also can play havoc with sealings, causing gaps to appear as it expands or contracts.

Overall, it’s an incredible guide with helpful tips and tricks for anyone logging data underwater for science or even just trying to waterproof their favorite watch.

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Gaze Upon The Swimming Mechanical Stingray, Made With LEGO

December 10, 2022 by Donald Papp 5 Comments

Stingrays have an elegant, undulating swimming motion that can be hypnotic. [Vimal Patel] re-created this harmony with his fantastic mechanical mechanical stingray using LEGO pieces and a LEGO Technics Power Functions motor. The motor is set in a clever arrangement that drives the motion remotely, so that it and electrical elements can stay dry.

The mechanical stingray sits at the end of a sort of rigid umbilical shaft. This shaft connects the moving parts to the electrical elements, which float safely on the surface. This leaves only the stingray itself with its complex linkages free to move in the water, while everything else stays above the waterline.

We’ve seen some impressive LEGO creations before, like this race car simulator and pneumatic engine, and the mechanical action in this stingray is no exception. Interested in making your own? The part list and build directions are available online, and you can see it in action in the video embedded below.

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Love Is A Burning Flame, And So Is This Underwater Burning Ring Of Fire

July 29, 2022 by Ryan Flowers 22 Comments

When Johnny Cash wrote “Ring of Fire”, he was talking about love. But when an unnamed follower of [TheBackyardScientist] took it literally and suggested making actual rings of fire — underwater — they rose to the challenge as you can see in the video below the break.

Of course there are several ingredients to underwater fire rings. First you need water, and a pool clearly does the job in this video. Second, you need flammable rings of gas. [TheBackyardScientist] decided to build a machine to create the gas rings, and it’s quite interesting to see them go through several iterations before settling on a voice coil based poppet valve design. We must say that it works absolutely swimmingly.

Lastly there needs to be fire. And for fire, you need something flammable, and something shocking. Forty thousands volts light up a spark plug, even underwater. The fuel is provided by what appears to be compressed air and acetylene but we’re not 100% sure. We are sure that it goes bang! quite sufficiently, as demonstrated by its aptitude for blowing things up.

We appreciated the engineering that went into the project but also the rapid iterations of ideas, the overcoming of serious obstacles and the actual science that went into the project. Even if it is just randomly making literal burning rings of fire.

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