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.
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.
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.
Cleaning cheap eBay boards in alcohol.
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.
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.
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.
At over 1230 km (764 mi) in length, $10 billion in cost, and over a decade in the making, the Nord Stream 2 pipeline was slated to connect the gas fields of Russia to Western Europe through Germany. But with the sanctions against Russia and the politics of the pipeline suffering a major meltdown, this incredible feat of engineering currently sits unused. What does it take to lay so much underwater pipe, and what challenges are faced? [Grady] over at Practical Engineering lays out out nicely for us in the video below the break.
A Bubble Curtain containing the disposal of WW2 ordinance
As with any undersea pipeline or cable, a survey had to be done. Instead of just avoiding great chasms, underwater volcanos, or herds of sharks with lasers, planners had to contend with culturally important shipwrecks, territorial waters, and unexploded ordnance dating from the second world war. Disposing of this ordinance in a responsible way meant employing curtains of bubbles around the explosion to limit the propagation of the explosion through the water- definitely a neat hack!
Speeding up the job meant laying several sections of pipe at once, and then tying them together after they were laid. The sheer amount of engineering, manpower and money involved are nothing short of staggering. Of course [Grady] makes it sound simple, and even shares his take on some of the geopolitical issues involved, such as Germany refusing to certify the line for use after the Russian invasion of Ukraine. So far, the $10 billion pipeline is unused, and even Shell has walked away from its $5 billion investment.
Be sure to watch the whole video for even more fascinating details about the Nord Stream 2’s amazing engineering and construction. Check out a Robot Eel concept for the maintenance of underwater pipelines too.
When you think of a robot, you probably don’t think of a ball of underwater algae. But a team of university researchers used a 3D-printed exoskeleton and a ball of marimo algae to produce a moving underwater sensor platform. It is really at a proof-of-concept stage, but it seems as though it would be possible to make practical use of the technology.
Marimo are relatively rare balls of algae that occur in some parts of the world. A robot powered by algae runs on sunlight and could be electromagnetically quiet.
