/-Transmission Received || Ansible-Sector-74 || To Prohibited Subject 248029:BA7-/

Trade Route Attacks

With the Triptite Federation being gently convinced to open their borders for trade, merchants from our glorious Glorspindle Empire have been hard at work extending our trade routes there.

However, there is currently a rather headache-inducing issue. Our trade routes pass through Manti territory, and the pesky Manti pirates in their Rammers have been pillaging every merchant ship they can get their greedy scythes on.

Manti Pirates

Our on-ship crew have been having trouble holding off their boarding-attacks, as these man-sized alien mantises have carapaces resistant to our ranged weaponry. Generally, they swarm our crew 3 to 1, and can attack from multiple angles by grappling off the corridor walls. They're born to kill, and just as often fight themselves when there are no enemies around, so only our most elite crew are capable of fighting them evenly in a melee entanglement.

Luckily, our blunt weapons can crush them like the bugs they are, but entanglement with their scythes is still a dance with death.

It is also difficult to find enough mercenaries for the cause. For now, we've been drafting citizens, but the Emperor is most displeased with their deplorable and often bisected military longevity.

Magnetic Corridors

Our brilliant Emperor has given us the task to fit our merchant vessel's corridors with electro-magnetic fields to protect from Manti boarding-attacks. We are hoping to make it hard for them to use their scythes, and maybe even stick their darned bug-carapaces to the walls.

You, as one of the members of our Imperial think-tank, are tasked with finding an effective implementation.

Should your solution be unsatisfactory, you will be personally volunteered to defend our merchant ships.


/- Decimator Admiral Cloverick -/


The Question:

Is it possible to install electromagnets in corridors such that Manti have trouble employing melee combat? And will this be effective enough to stop the Manti Pirates?


  • Has to not harm our own space-humans. We tried blade-corridors, but constantly cleaning human and Manti gunk off the corridor-walls in space has been bad for morale.
  • Has to not harm the ship in its activation.
  • Has to give an advantage to the humans if they must engage in melee combat.

Technical Details:

  • The Manti are mantis-like man-sized aliens with carapaces 15-20 pounds in weight, 3 pounds of which is iron.

  • The Manti primarily employ their iron scythes for combat. Their iron scythes are bladed appendages 30-40cm long and weighing roughly 200-300 grams. They are detachable, but grow back very slowly.

  • Manti are extremely agile, but possess half the strength and body weight of an average human male.

  • Manti have carapaces capable of deflecting our ranged weaponry, but their internals are very sensitive to blunt-impact.

  • Manti have iron nails that allow them to partially puncture into hull and walk on corridor ceilings

  • Manti boarding swarms consist of 15 members, outnumbering combat-crew 3 to 1

  • The Manti perform boarding attacks by ramming ships, and then streaming through the corridors from the apertures opened by the collision. They can theoretically come from any corridor on the ship.

  • Corridors are usually cramped, 10 meters long, and 2.5-3 meters in diameter.

  • Corridors have (some) artificial gravity.

  • Ships have auxiliary generators capable of providing large bursts of energy for fifteen-twenty minutes.

  • Most corridors between rooms do not have sensitive electronic equipment.

  • Our human crews have access to melee weapons not affected by magnetic fields, but aren't as proficient in melee combat as the Manti.

/-End of Transmission-/

  • 1
    $\begingroup$ if they are suicide rammers , the problem solves itself. not very pirate like, though. $\endgroup$
    – ths
    Commented Sep 4, 2022 at 23:54
  • $\begingroup$ @ths that’s just what their ships are called, as they ram into ships almost suicidally. The ram itself will puncture a hole for entry. Will clarify in the question. $\endgroup$
    – Enthu5ed
    Commented Sep 5, 2022 at 3:46
  • 1
    $\begingroup$ A couple of points: 1. 30-40 cm long and 200-300 g is not a scythe, unless that is just the blade. Maybe you mean a sickle? Too little mass to be effective as a slashing weapon against any armour in any case. 2. The carapaces are 15% iron, but we don't know what percentage of their body mass their carapace is. 3. "do not possess much strength" - along with details of carapace mass, we need to know how much strength, otherwise we can't say how impaired they will be by a given magnetic field. $\endgroup$ Commented Sep 5, 2022 at 3:50
  • $\begingroup$ @KerrAvon2055 good points, I don't want the question itself to become hard science, so I had left some details more open-ended, but these details would definitely be relevant. Scythes in this case refer to their bladed appendages. We can assume they possess as much strength as half that of an average human male. As for the carapace, let's assume about 20 pounds, a few times heavier than a bullet proof vest. The iron composition would be 3 pounds, mostly woven into the carapace. $\endgroup$
    – Enthu5ed
    Commented Sep 5, 2022 at 4:00
  • $\begingroup$ As for the weight of the scythe, this is roughly the same weight as a standard dagger. Medieval rondel daggers were often used to puncture chainmail, and sometimes even the joints between plated armours. We can't expect the space crew to wear full plate armour, and also can't expect these vulnerable space crew with only ranged combat expertise to fight off 3 bloodthirsty assailants in a melee. $\endgroup$
    – Enthu5ed
    Commented Sep 5, 2022 at 4:16

2 Answers 2


...Static clearing... Officer third-class sub-bridge deck monitor station X9-227/H reporting on latest attempt to thwart a Manti invasion. Refer to High Command Assessment Report 4421-A29Z-XX47 Executive Summary for review of intent and expectations... Will continue report after static clears...

HCAR 4421-A29Z-XX47 Executive Summary (unredacted): It is our belief that the high iron content in Manti physiology constitutes an intrinsic weakness that can be exploited using the simplest of physical forces: magnetism. The Science Directorate under orders from the High Command (see 11/88-LW/446 dated 9927.33) has equipped the Electorate, an older class cruiser that will not constitute a statistically relevant loss to future engagements should the experiment fail, and assigned a crew of very young and inexperienced astronauts or very old and obsolete astronauts to carry out the experiment. Mark-27 electromagnets have been installed under the floor plating on decks 13-19, which 87% of the time are the decks of choice for Manti incursions, with control given to the internal security officer with strict orders to use them should the Manti attack. The Electorate was then ordered to a sector of space known to be riddled with Manti attack craft and given assurance that the area had been cleared for the purposes of new crew training....

...ommand? Are you rea... Clear, command. Continuing report. We found the use of electromagnets initially effective, but must report considerable casualties and damage to the ship...

The Good, the Bad, and the Ugly

The Good

Oh, yeah. You can install them and given strong enough magnets, just flip the switch and watch those iron appendages snap right to the floor. No problem there. You'll need to go man-to-Manti and whack each one before turning off the magnets, so there is still a bit of clean-up compared to previous experiments, but it does stop the attack.

The Bad

The fundamental problem with magnetism is that there really isn't a way to stop it. Faraday cages, for example, stop (when used properly) electromagnetic signals, but not magnetism. So when you turned on those magnets, the somewhat ferrous spoon the captain was using ten decks up snapped from his mouth, through his soup bowl, and embedded itself to the floor. He'd be suing the High Command for his dental work if it weren't for...1

The Ugly

You can't do this unless pretty much everything in your ship is 100% resistant to magnetic influence. That means the ship has no ferrous components. No electrical signals can be anywhere near the affected corridors (at least not important signals). Anything that is ferrous in nature will be stressed every time you use the magnets — including the ship's infrastructure. And if those magnets happen to be back where the proverbial fusion drive is with its magnetic containment...

...well... that's why the captain isn't suing the high command for his dental...

It's also worth noting that magnets of that size are heavy, kinda large, and take a boatload of power — all of which are bad things for space ships. But hey! If various SciFi franchises can hand-wave the fact that everybody's walking around comfortably on their space ships with "gravity plating," then there's nothing at all stopping you from magnetizing your deck plates.

But there are some possibilities that might be more efficient

Do you really need to magnetize all the decks? Why not magnetize the door frames? Create choke points that clog up the works. After all, this solution won't actually stop the Manti because they're sitting there with their appendages (and possibly their carapaces) stuck to the floor spitting and hissing and just waiting for someone stupid enough to come close enough for them to kick really hard. And they're everywhere because Officer Third-Class Sub-Bridge Deck Monitor Station X9-227/H was 20 seconds late flipping the stupid switch. It's impressive how much ground a mad Manti can cover in 20 seconds.

Magnetizing the doors raises believability by creating a situation where the Manti are contained until they can be taken care of. Which is a good thing, because by ramming your ship they cause a honking lot of other, much more immediate problems.2

Incursions with an unpredictable entry point are why SciFi has traditionally employed gas (the dread "anesthizine gas" comes to mind). It's something that can be employed with little risk to the ship itself and can be distributed anywhere (and, if necessary, everywhere) in the ship. But since it's been used, I can see why you'd prefer not to use it.

Another area-of-effect solution, however, depending on how you're shielding your ship, is to use heavy water (D2O). Heavy water is one solution for shielding ships from radiation. And you could flood corridors with it. Seal the offending area, flood away, wait for the Manti to drown, pump it out, clean mess. Of course, you might not have enough water to flood their ship, but weaknesses are your friend when it comes to writing a good story.

Finally, your tried-and-true solution might be to simply open the corridors to space. How well can the Manti survive a vacuum?

1OK, ten decks up is a bit of a stretch. Magnetic strength decreases really rapidly with distance. All those Hollywood movies that show magnetism magically pulling people's stuff through glass windows (I'm lookin' at you, Fast & Furious 9!)... yeah. That would take a magnetic flux that's breathtaking to contemplate. So I stretched the truth a bit for dramatic effect. The Q's tagged "Science Fiction" after all. I'm not even going to mention the localized gravity field in The Chronicles of Riddick that pulled Vin Diesel to the floor and how that would affect the ceiling....

2Like explosive decompression, loss of whatever shielding you're using on that side of the ship to protect you from high-speed particles and radiation. Structural problems threatening to tear the rest of the ship apart. Loss of power and control distribution across a significant chunk of the ship, and who knows how many lost souls that were useful for something and are no longer doing that something anymore. Poking a big hole in a ship is a big deal. The invading force just might be low on the list of urgent issues.

  • 2
    $\begingroup$ A commendable report, member JBH. You have made great effort in delivering both high quality experimental data and excellent feedback. It will be relayed posthaste to our engineering teams on Merchant Planet M17 for further testing. As your reward, your voluntary retreat to defend our ships will be delayed, though we must send someone in the interim. The extended reward being permission to ‘recommend’ one of your colleagues for this glorious position. Lightspeed/-Decimator Admiral Cloverick-/ $\endgroup$
    – Enthu5ed
    Commented Sep 5, 2022 at 5:13
  • $\begingroup$ Fitting the magnetism to corridor doors or limited surfaces is definitely a good potential solution. By doing so and limiting the strength of the fields more, it might be possible to employ electromagnetic shielding in other areas of the ship. I have a feeling corridor placement is also crucial, especially if they start getting used as defensive chokepoints on ships. The oxygen method is the goto in the game FTL, and I am also wondering why the emperor didn’t think of it. Maybe the Manti have tech specifically made to breach doors? Thanks for the varied answer, it covers a lot of great points! $\endgroup$
    – Enthu5ed
    Commented Sep 5, 2022 at 5:27
  • 1
    $\begingroup$ Accepting this as the answer. Thanks! $\endgroup$
    – Enthu5ed
    Commented Sep 6, 2022 at 9:24

Induction coil corridor.

induction coil

Induction heating is a fast and efficient contactless method for heating conductive materials such as metals and semiconductors by applying a fluctuating magnetic field. Recently, it has become one of the preferred heating technologies for industrial, medical and domestic applications due to its advantages over traditional heating techniques...

In induction heating, an alternating current (AC) source is used to supply current to an induction heating coil. As a result, the coil generates an alternating magnetic field. When an object is placed in this field, two heating effects occur:

hysteresis losses – these occur only in magnetic materials such as iron, nickel, cobalt, etc. due to the friction between the molecules when the material is being continuously magnetized in different directions... eddy-current losses – these occur as a Joule heating effect in any conductive material because of the electric currents induced by the fluctuating magnetic field.

You have induction coils wrapped around your corridors. They are out of sight, just on the other side of the walls. When a corridor is breached, you turn on the coil. Wait until it is full of Manti because once the smoke starts they will not keep going in.

Your coil will heat the iron parts to glowing. Non iron parts will cook inside the carapaces. The trick is to turn off the electricity at the right time when the manti are cooked but not overcooked. Experienced crews can tell this by the delicious smell of the smoke and steam coming from the corridor.

  • $\begingroup$ In the interest of keeping the question specific, I had not asked for alternative solutions, but this is certainly a very interesting answer! $\endgroup$
    – Enthu5ed
    Commented Sep 7, 2022 at 18:35

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