# Ship design that could navigate on the edge of an incredibly strong vortex

I'm developing a game set in a colossal landmass at the center of a vortex, with water walls dozens of kilometers high. The continent is somewhat circular, and no civilization has yet developed seafaring technology that can survive the vortex itself.

During the game, different civilizations go to war, and one of them develops a plan to take by surprise the capital of another by riding the vortex to get "behind" the defending forces.

Is there a design that could help a ship survive fairly reliably the extremely strong but otherwise fairly regular currents? Keep in mind that the water is spiraling up, not down.

I have a few ideas about how to solve the "water direction" problem (ballast, or a ship hull that forces the ship to go down, so that the upward thrust of the water is balanced), but otherwise I really am...out of my depth!

1. The vortex is an annulus (a ring), but I can't think of any way in which the inhabitants could test wheter or not this is true.
2. The continent is a disc, it's flat.
3. The total landmass is about 100 million square kilometers, 50 million less than earth's own landmass. It's pretty much a smaller pangea.
4. The vortex needs an incredible amount of energy to be sustained, and the movement of the water walls create very, very strong winds near the coast. This prevented pretty much any kind of development in seafaring technology, because it's considered madness to "challenge" the vortex. It's why the idea of exploiting its motion to attack another city is crazy enough that it might work. But it needs a ship with some form of ballast (be it physical or simply a design peculiarity that makes the ship tend to go down instead of following the current, that spirals up), and a design that accounts for the immense amount of energy in the elements surrounding the ship.

Basically, the ship needs to be strong enough not to be torn apart by wind & water.

• Is the 'vortex' is an annulus? or does it expand infinitely away from the continent? If it is the latter - Is the continent on a spherical planet or a flat world? If it is an annulus, can you give some approximate dimensions? Sep 16, 2014 at 23:26
• @NauticalMile 1) it's an annulus, but I can't think of any way in which the inhabitants could test wheter or not this is true. 2) The continent is a sort of disc, it's flat. 3) Total landmass is about 100 million square kilometers, 50million less than earth's own landmass. It's pretty much a smaller pangea. Sep 17, 2014 at 12:48
• @NauticalMile the more I think about it, the more I'm convinced that for all intents and purposes the outer edge of the annulus should be considered infinitely large. Sep 17, 2014 at 13:02
• What distance is being traveled here? Would they be able to use a sealed vessel or do they need something where they can get out on deck? Sep 17, 2014 at 17:24
• @TimB Hundreds of miles. As for the vessel, direction is pretty much guaranteed due to the flow of the vortex (it goes clockwise), so as long as the crew is able to see if they're going too high or too low a sealed vessel should work nicely! Sep 20, 2014 at 11:22

I assume you're talking something like this:

except it's upside down and the air is water and the water is air?

Consider surfing, for example. On a large wave, you are riding down a hill of water, the surface of which is moving (relative to you and the wave) up. Assuming you could control how you are pulled by the upward force, I imagine that you would be able to ride the vortex with the circular flow, since you can keep yourself from being pulled up. Of course, if it's getting steeper the closer you go to it, it doesn't matter what special features you have to keep from being pulled up. If you're not super light, eventually the upward force of the water and the slope of the inverted vortex will cancel each other out. The only special thing that would matter is to keep from tipping over.

Since I assume the circular pull of the vortex would be very strong, there's actually not any real reason why it wouldn't be a common, energy-saving tactic to simply sail with the vortex. It wouldn't be something special or odd - it'd be expected. Chances are, there'd be minestrips laid and defenses set up on the side of the vortex where the enemy would be anticipated to enter, so where the vortex is pushing water towards you.

On that note, what would be surprising and unanticipated would to go around the vortex the other way: against the flow.To do that, you'd want to be as unaffected by the circular flow as possible, so you'd want to rise high out of the water. Today, the fastest ships are those which are basically flying above the water, held up by aircraft-like "wings" on struts under the ship.

Original Source

Given that you'd be going against the flow of the water, it'd be easy to get enough waterspeed to lift up out of the air. Stick a large fan or a sail (if the winds aren't going with the water) on the ship, and you'd be well able to navigate the rim of the vortex backwards.

Alternately, you could place a sort of sail underwater, using the water as the driving force instead of wind, and tacking against the vortex as you would into a headwind.

Also alternately, you could again use a hydroplaning ship with a crosswind to blow yourself up onto the center of the vortex and then surf down, turn back up and repeat. You may not actually make any headway, however, depending on just how strong the vortex is.

• Darn it. I just reread the question, and the landmass is at the center of the vortex. Ugg. I'm posting this anyways, as some of the ideas would still work possibly for getting over.
– neph
Sep 17, 2014 at 1:07
• Oh. You could also ride the vortex, using some kind of wide upside-down T-shaped plane under the ship to keep it on the water, and then have a large wing perpendicular to the water (parallel to the ground), which, as the ship is spinning around, would keep it rising up.
– neph
Sep 17, 2014 at 1:08
• You've given me some great ideas! I'm afraid I didn't explain myself well enough, though: the problem would be that the current of the vortex is so strong that nothing was ever built that could resist long (due to the water walls' movements there would also be incredibly strong winds). On the edge of the continent there is nothing because of those problems. The idea, if correctly implemented by the attacking civilization, could succeed because it might just be crazy enough that no one would expect it Sep 17, 2014 at 12:57
• Ooh. Give me some more time, I may come up with something.
– neph
Sep 17, 2014 at 15:35
• I want to see a video of so many of the ideas being discussed on the various answers/questions on this site. Sep 18, 2014 at 15:44