Hello everyone,

I'm working on a novel which has an aztec/Hawaiian themed civilization which lives exclusively under water. There is almost no magic and I'm trying to devise as many realistic weapons as possible. I am an inviting you all to come along on this thought experiment with me.

I already have Spears and teeth knives and bone rondels, but I'm conflicted over tridents and swords. What other ideas are there for weaponry?

These are intelligent sea creatures with arms, no dry land use allowed. Metal is out except for gold and copper maybe. I love the idea of utilizing sea life but I'm looking for some ideas for how to do that?

I want to make venomous armor somehow, but all the ideas I have would accidentally poison the wearer.

How could squid ink be employed? I am thinking of a Pike with a chambered end which expells contents upon impact. Also a projectile which does the same which can be dropped or made buoyant to attack from below.

As for melee weapons, what do you think off tridents. They have a great undersea feel but I don't think they would be very good cuz the water resistance on the extra tines would slow down the weapon too much. However a ranseur or bill/ partisan weapon with hook would be great I think, cuz it would allow one to attack someone inside of reach with only the need for pull back and it would give you a surface to catch Spears on. Also the inside could be lined with teeth.

Lastly, what do you all think of a saber underwater? Like a super curved tulwar/ kilij type? I'm thinking it could be made think but wide with whole drilled through the wood to facilitate turning the weapon and it would be used close in for draw cuts. I think pulling a half circle through water would be easier than swinging one because the weapon is already displacing water so really it is the pommel which would move through, and the rest would just follow in the wake.

The pictures here might give you some ideas of materials:
https://gizmodo.com/5994118/15-human-weapons-made-from-animal-weapons

Fictional:
Animals with gills don't have lungs (obviously), but if it is a fantasy creature that had some internal bladder that they could fill with water and then compress to expel the water forcefully, they could hypothetically use a type of blow-gun. Maybe they harvest a type of narrow yet long "tube coral", and snap-off the quills of sea urchins to use as the ammunition (blow-darts). Not sure of the potential physics problems it would cause, but if you are pushing out an uncompressible liquid (water) through more water, it should work as well as air pushing through air (blow-gun). A dart would have less drag than a spear gun.

And since we're on spear guns, maybe deep under water they have access to a very highly elastic components of sea-life (tendons of a giant sea turtle or the treated skin of a massive sea snail) that they could stretch to hold potential energy and use that to throw short bolts/spears with sharp coral or shark tooth points.

But now that I'm thinking of elastics and projectiles, do a google search for POCKET SHOT, and contemplate the possibility building something like that out of under-sea components or some undiscovered deep sea creature that just happens to have a hard shell or stiff cartilage, and when you remove it's innards basically makes a pocket-shot. Once again, heavy dose of imagination required.

If you want poison armour, they could gut various species of scorpaenidae (lionfish, stonefish) and strap the "hide" or skin on their body. Scorpaenidae secret a highly toxic mucous from glands just under the skin. I presume it would be quite dangerous to be poked by a lionfish quill long after its death. And seeing an opponent adorned with giant lionfish quills would look simultaneously scary and amazing.


-Terry

There is wood and the world isn't completely submerged or anything. The world at present is already mostly water, this world is similar.

Hi there. I love speculative fiction. This reminds me a lot of the setting of the science-fiction story "surface tension" by James Blish. If you haven't read it, do yourself a favour and do so! It is brilliant.

A few points regarding the hydrodynamics and other aspects of fighting underwater (I have some background in flow mechanics):

The drag on an object moving through fluid (air or water) is proportional to density of the fluid and to the square of its speed through the fluid, and its frontal area. So, in layman's terms, there will be roughly a thousand times more drag on an object under water than through air, all other things being equal (speed, shape, etc), and an object traveling at twice the initial speed will experience four times the drag force in the same fluid, making it slow down more quickly than the same projectile moving more slowly. These effects stack (to be precise, they are multiplied). However, if the object is moving relatively slowly (like punching fists, kicking feet or swung weapons), the drag will still be relatively small. Faster moving projectiles are much more heavily penalized - however, they will still be effective at close range, although their actual range will drop off much more quickly. Spear-guns do work under water, after all. This will be worst for objects which are not well streamlined like roughly spherical slingstones or thrown rocks. Arrows or spears will be ok for shorter-range engagements though. Short bows or crossbows will be slightly better than longbows because of the lower speed and length of the arms, but the penalty shouldn't be very great unless the bows are extremely long-limbed.

Weapons like swords or thrusting spears will also not be badly affected; again because they are relatively well streamlined and have a very small frontal area. Even the extra tines of a trident won't be very restrictive (because their sectional area is not large). A large, low-density blunt instrument like an archer's maul may be slightly less effective than a metal or stone-headed mace, though, and long cutting or clubbing polearms such as glaives, halberds or holy-water sprinklers may have a slight penalty associated with the higher speeds of their business-ends when swung.

Now, regarding poisonous armour (and moving far out of my field of specialization): some creatures have developed a resistance to certain types of poisons because the more resilient individuals survive longer and get to breed, and most creatures can develop a tolerance to many poisons through regularly being exposed to small but gradually increased doses. So perhaps one insular clan or group of your undersea people (possibly assassins or a religious order of holy warriors) have regularly exposed themselves to the toxin of a certain creature to gradually develop a resistance to it (possibly by donning the poisonous armour for ritual combat) - and only those who did not die or become sickly would presumably go on to breed the next generation. So through a combination of artificial selection and aclimatization, they'd be able to wear toxic armour.

Finally, remember creatures which are well-suited to an aquatic existence will presumably have sufficient muscular strength and well-adapted (ie. streamlined or otherwise adapted) limbs and bodies that they would be able to do things that we, accustomed to life on land, could not. So the greater frictional resistance of the water would very probably not impede them nearly as much as it would us, assuming most other factors are similar. If this were not true, they'd be sitting ducks for predators, etc in their world, and would not have survived.

Anyway, I hope this helps

Andrew

I might consider using bone instead of wood. Other possibilities would be Narwhal tusk, Walrus tusk or Sea Urchin spines. Maybe even a Sawfish rostrum? Or even items repurposed from a shipwreck?

Stingray barbs work as daggers and spearheads (either singly, or a spearhead with multiple barbs).

Porcupine-fish helmets:
[ Linked Image ]
http://web.prm.ox.ac.uk/weapons/index.php/tou...index.html
http://www.britishmuseum.org/research/collect...p;partId=1

Thank you Andrew and Timo. My only problem with the porcupine fish idea is that drying isn't an option since things will neither get dry nor stay that way under water.

Andrew, drag is a big concern for me and I have limited my weapons to piercing and push/pull cuts. I think a nagamaki like weapon, with a curve all the way through the handle might be good, because the extra drag would be countered by the extra leverage of the handle. In addition both this and my saber are highly curved because then the blade will being moving through the pommel's wake. This means that my pommel's have to be hydrodynamics, but obviously the races have already learned the ends and outs better than I have and build everything like that already. What do you think?

Thank you Don, I'm using bone for points rather than for the body of most weapons. To answer the material question, drift wood and ship wrecks provide wood and more importantly, buoyant building material. There are large crabs and fantasy plants which are resiliant enough to act in lieu of wood, but these are dense, so they are used as cheaper building material,. Wood is expensive high end stuff.

Yes all those exist. But there is no trade between them and the aquatic people are exclusively so. I didn't mention it cuz I don't need help with the world building, only weapon designs.

OK, weapons suggestions only ..... :D :cool:

I wonder if a fire weapons might work under water ? Something like a magnesium flare or some weapons using thermite lances or thermite grenades ?

I don't think they could manufacture those under water. But what do you think about sewing sea anemonea or jellyfish into bags and then flipping them inside out to turn into poisonous gloves?

Second idea. What about a naginata underwater with a shark tooth blade. Also how could Jade be used?

Hi again Michael

A few more points on hydrodynamics:

Regarding the drag/wake of sword pommels : the pommel is the slowest moving part of the sword, so even if it is quite large and has a high drag coefficient, it will not contribute much drag. Many western pommels are actually quite streamlined by design (think of a brazil-nut, for instance), as these shapes are also comfortable to hold and aesthetically pleasing. The point is the fastest moving part, of course, but it is very thin and well streamlined by design - it has to be in order to cut.

On the other hand, a polearm is not well streamlined (cylinders in crossflow tend to experience a phenomenon called laminar flow separation, which hugely increases drag), and (more importantly), as the length of the staff goes up, the speed of the staff tip increases roughly linearly, which means that the drag - increases proportional to the square of the length increase, therefore the resisting moment due to drag will increase with the cube of the length. However, the extra moment which you can apply to the staff increases linearly as you move your hands apart - but only up to a point, as you can only hold your hands so far apart on the haft, so you'll not gain as much as you might expect, relative to the extra drag penalty. So short is definitely better than long (this applies to swords too, of course, but less as they are better streamlined). Though blade-flat-first movements (like Meyer's slaps with the flat of the blade) will suffer a pretty large penalty in terms of drag - you probably won't want to use those.

Now, regarding the need for swept blades: swept wings are used on high-speed aircraft that travel near or above the speed of sound because under those conditions, they avoid certain problems associated with gas compressibility. At the much lower speed at which swords and hand weapons are swung, you will not see this benefit (in addition, the speed of sound in water is much higher, so this will be even less of an issue than in air). In fact, even at supersonic speeds, straight wings are not a problem drag-wise, if they are thin and sharp (look at the pictures of the bell X-1 and lockheed f-104 starfighter, as well as many supersonic missiles that have straight unswept fins). Swept wings on lower-speed aircraft like the DC-3 or some biplanes are usually to adjust the center of lift without changing the wing attachment point, or to improve stability, not decrease drag. Anyway, the point is that straight swords or polearms won't be noticably worse than swept/curved ones under water in terms of drag (though they may have all the other usual advantages and disadvantages).

A thought: have you experimented with moving a sword underwater? If you haven't, then, to do this safely, you could probably sit or lie next to a deep swimming pool, dangle one arm with a sword in the water, and try swinging it back and forth in an arc, then performing a similar motion at a similar speed in the air. I suspect that you'll find that the drag is much less than you might think.

Also, anyone else with an engineering, physics or applied maths background, please check my logic (I've certainly been wrong before)

All the best

Andrew

Unfortunately Andrew, the Pacific ocean is currently between me and my weapons, and probably will be for the rest of the year. I was actually thinking of getting a snorkel and using my cheap stainless steel wall hangers, but I don't have any polearms. Now in regards to polearms, what about straight thrusts, using the edge for slicing instead of cutting? Also, what if the haft isn't cylindrical? It could be Appleseed shaped. That would help with edge alignment too, though I don't think that would matter much underwater

Also Jean, I think spines and poisonous coral or spikes from lion fish are probably a much safer idea.

Hi Michael

The stainless steel wallhangers should be fine, provided they don't come apart - even one of those plastic wasters (or a well-sealed wooden waster) would work fine, provided the blade wasn't too thick. In fact, a thin metal bar or very thin hardwood slat would give much the same effect - you just want a rough idea how much resistance you will experience in cuts. Actually, a blunt weapon-substitute has the advantage that you can more safely hit something (a wooden log, say) underwater.
The point is, that even if the lousy dynamic properties of your weapon-analogue dominates the drag on it, you then know drag isn't a big issue.

Thrusts with polearms (or swords) are fine - the frontal area is so low that the skin-friction drag is minimal. Even the drag on the wielder's limbs (which is not large) will probably be bigger than on the weapon. I suppose a godentag-like polearm with a bulbous section, or an ahlspies with a huge disk-guard might be a slight exception, but even then it should be quite usable.

An apple-seed or elliptical profile for your polearm shafts will certainly help somewhat, but you need to have a fairly slender profile to see much benefit. An 2:1 ratio elliptical profile should theoretically reduce the drag on the polearm by roughly half (it will still be more than double what a sword blade of similar length would be though) and if you go for a higher ratio, your weapon haft becomes uncomfortable to hold and potentially weaker in the transverse direction. It could make the difference for shorter chopping polearms, though.

All the best

Andrew

Andrew, what is there were holes drilled through the front edge of the haft as well? I have been wondering about venting holes and voids on flat surfaces in general to lessen drag. I came up with a shield design, which is basically a spoked wheel held at the hub. By turning it the spokes can be used to catch incoming objects, and I was thinking that making the spokes into flat slats with holes drilled through them the drag could be ameliorated. Also, maybe I am wrong here, wouldn't the outside wheel edge spin freely since it is already displacing water? Would the skin friction on the the rim be very large? Think of small targe sized round shields.