Are there any electronic devices that can be used to electrocute people in water, like, say, beach goers in the ocean? The weapon would need to be installed under the water in advance and then be selectively activated on/off by a controller. Apparently there are already underwater electrocution devices to use for killing sharks, but I haven’t found much information on how they work exactly. I’m writing a character whose M.O. is electrocuting people while they’re in water, and am wondering if there’s a way for them to do this from a distance (rather than dropping an electronic device into the water right in front of people). I’m thinking maybe there’s a power line that goes from under the sand to a hidden location, where the activation switch is, and then that’ll send a current through the line, zapping everyone within a certain radius. But I don’t know if there’s a better way for this to work…
You have a battery or capacitor that pumps current around a circuit, of which the water is a part. The current leaves through the cathode (the metal hull of the ship), goes through the water, then returns through the anode, which is set a distance away from the cathode.
Bio-Robotic Electric Eels
A particularly sinister approach to this brand of cruelty is to use electric eels. Normally electric eels prefer not to attack humans, but when they do it is often fatal. The trick is to be able to control them into actively hunting and killing humans and that is where bio-robotics comes in. In the past few decades, scientists have been learning to remotely control a number of organisms using brain implants including mice and pigeons which have brain complexity least as high as that of an eel.
The hard part would seem to be insulating the implant against the eel's own electric discharge, but since the eel is able to not electrocute itself, it is likely that any subdermal implant would be fine.
As for range, a 2002 experiment allowed researches to remote control rats from a distance of 1/2 a kilometer. That said, the recent drone crazy has incentivized much longer range more efficient remote control interfaces than we had 20 years ago, so ranges of 2-8km would not be all that incredible considering modern technology.
The best thing about this option is that you don't need to do any complex installation of powerlines in advance. You can just sail near the beach you want to attack, release a swarm of eels, and once the attack is done, your weapons could literally just swim right back to your boat to be brought back to your base of operations leaving no evidence behind for investigators. If you are particularly cleaver about it, you can stow the eels in an underwater compartment on your ship so that if the Coast Guard tries to search your ship, the most they would find is the laptop and radio equipment you used to control the eels... and a ship without a laptop and radio equipment is more suspicious now a days than a boat with one.
As a side note, this method is best deployed in fresh water since electric eels are fresh water fish. If you plan to attack someone is a salt water environment, you will want to use electric rays instead. While not as electrogenic as their freshwater counterparts as to be able to instantly kill a healthy adult human through electrocution directly, stunning a human in the ocean is still likely to lead to death by drowning.
This one is a bit out there.
An electrolaser is an experimental weapon that uses laser to create a plasma channel of air in order to create a conductor. A electric shock from a capacitor is then released allowing electrons to flow down the beam of plasma and shocking the target. Adaptin this to underwater would be a little difficult, but not terrible. The power output of the laser would need to be increased, but the channel would actually be preserved by the conduit of steam that would surround the superheated plasma.
Using this as the main shock device, the perpatrator can shock individual people, or aim at a large chunck of iron in the water and shock it. It should be noted that the power requirements of such a device would be severe, and it wight leave a small trail of bubles to the location the laser was fired from, so our super villian may get caught by a passing fishermen. Good luck!
Everything in life is better with rockets[citation not needed]. There is a technology being developed these days called Rocket Triggered Lightning and it's awesome. which allows you to shoot a cloud with a rocket that carries a grounded wire. When the cloud is hit, a lightning forms through the wire.
You could do much the same thing. Shoot a supercavitating torpedo against the victim. When the torpedo approaches to the victim, it shoots a net around them. Then the torpedo breaks in two - one part of it dives down to the sea floor carrying a wire, while another part becomes a sea-to-air missile carrying the rest of the wire to a cloud. Click, click, KABROOM!