How to defend a sailing ship from a wyvern

Question

Pirates are always a threat, but this particular coastal city has another worry - wyverns. In order to get from said city to open seas, the ships must traverse about 600km towards the exit from the Bay, and as it happens the wyverns nest on southern shore, which means that its common for these creatures to be flying over the entire bay. As they are also hunting here, it inevitably means that ships also get attacked.

How would the humans effectively defend their ships against these creatures?

The focus is on safety of the crew and ship, not necessarily on killing the wyvern.

More about the wyverns

EDIT:What I describe here as a wyvern is my version/take on it and as such it is different than the common depiction of a wyvern.

A wyvern is essentially a snake, with bat-like wings attached to its ribcage and a rather muscular pair of legs located in the hind section of its body. An adult wyvern we expect to encounter can range from 15 to 40 meters in length and about 35-60m in wingspan. It's entire body with exception of wings is covered with scales which offer protection similar to plate armor - arrows will likely bounce off at medium and long ranges, but crossbow bolts are more likely to penetrate.

The wyevern has an animal level of intelligence (it is not an intelligent race), heavily reliant on instincts. It exhibits no magical abilities.

Why do wyverns attack ships?

They mistake them for prey - basking whales.

How do wyverns attack?

Two options:

• Diving attack

  If a wyvern is at high altitude (over 1000m) it will dive down towards the target. Contact with prey will be made with jaws first, legs second. Wyverns were reported to kill whales with sheer force of impact with this method.

• Level attack

  If a wyvern is at low altitudes it will usually circle the target first. If it comes to the conclusion that sails do actually look like whale blow, it will attack in a swooping manner, heading directly at the target, seeking to strike with legs first.

The diving attack is more common, because a wyvern investigating a target in the second method will often realize that it's not a whale and leave. High-flying wyverns are also more commonly enocuntered. Wyverns can occasionally be encountered swimming in the water, but they do not display predatory behavior when not in the air and will leave if disturbed.

What if a wyvern successfully attacks a ship?

It will get very confused about biting into a piece of wood with humans crawling over it, rather than a juicy whale. It will leave, but at that point the damage to ship and crew has already been done. Smaller ships can be outright sunk.

More about technology

The ships in use are wooden sailing ships ranging from ships similar to cogs, carracks and caravels to ships more like the galleons or brigantines. Technology level could be described as roughly that of high middle ages in most aspects. Magic exists, but mages are rare.

No gunpowder weapons are in use.

Bows and crossbows are most common ranged weapons, and various siege engines are also in use in warfare.

Things I've considered

Siege engines similar to ballista or scorpion seem to be my first thought, though there are several issues. They would need to be mounted in a way that allows for elevation and traverse of the weapon to track the wyvern. They are also rather expensive and large pieces and only one, maybe two could be mounted on a ship, especially if that ship is supposed to be a merchant vessel. Additionally the sails would get in the way of aiming and aiming itself will not be easy.

Perhaps it would make more sense for the city to field a number of small vessels built solely for the purpose of protecting other vessels from wyvern attacks. These ships would escort other vessels accross the bay and return to port afterwards. That could allow more expensive solutions and dedicated designs, rather than trying to squeeze an apropriate weapon on a regular vessel. The city would likely be willing to spend a lot of money to ensure the safety of its main trade route.

This is my first question, so please let me know if information is missing or unclear or if theres otherwise something I need to add or fix. Thank you for your time.

Answer 1

First off -- dye.

Color the sails a dark, striking color. Red, maybe. This chiefly helps with the level attack by confirming that it's not a whale.

Or use disruptive coloration. Which probably would apply to the deck as much as the sails. Break up the outline of the ship so that no longer looks like a whale. Black and white work for this

Second off -- distractions.

When a wyvern looks like it's about to do a diving attack, use the ballista to launch something into the sea calculated to make a plume -- one that looks more like a whale that your red sails and deck in black and white.

Finally, your dedicated escorts may have additional weapons to use on the wyvern. Smokescreens that cause it to choke would be useful for discouraging it from ever trying those strange looking whales again.

Answer 2

I would recommend using a form of a smokescreen.

Basically, when a wyvern is spotted, they deploy the smokescreen, hiding the ship from the wyvern. The wyvern can't see or smell its prey due to the smoke, so it abandons the hunt and flies off.

Another option is a hail of arrows. Basically have a squad of archers that fire longbows at the diving wyvern, due to the attack (which is in reality probably barely damages the wyvern) it realizes that this is no whale. And so it flies off, looking for easier prey.

All in all, it is best just to use a form of attack that lets the wyvern know that your ship is not a whale, so the wyvern looks for easier prey.

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Edit: Another idea that I have come up with is mini catapults. Arm either your ship or your escort ships with miniaturized catapults. Though not very accurate, the flinging of large rocks at a diving wyvern will still act as a deterrent. You do need to be careful with the trajectory of the rocks though, you need to make sure the rocks fall into the water, and not onto the ship. But a nice additional effect to flinging rocks into the ocean is that the splashes they make can look like whale spouts. This will then give the wyvern a different, potentially easier, target.

Answer 3

Another option could be colors. Bright colors are nature's normal way of saying "do not touch." Assuming that your wyverns aren't color blind, your people would need to paint the top decks (and possibly sails) for their ships bright, perhaps borderline garish, colors. It could add an entire industry to the world, and cheap of shady transport companies would always skimp on the rather expensive paints and dyes required, adding some drama to the crossing. That's my idea for passive defense.

For active defense, as you've ruled out gunpowder (a Hwacha in a vertical launch attitude would be great), I'd still go with something similar. I'm not sure on the engineering on this, and it would be a right pain to reload, but some sort of high angle, multiple arrow/bolt system would probably work. Maybe mounted in a enlarged crow's nest at the top of the ship. Wyvern dives down gets a burst of arrows/bolts to the face/underbelly, and either decides to abort, or flinches away due to pain and impacts the water (probably severely injuring it, if not outright killing it, in the process).

Answer 4

I'd say:

• More people than normal would be dedicated as naval lookouts to detect wyverns as early as possible to give the crew time to react. Given that it's an airborne creature, time between the start of its attack and impact is probably less than one minute.
• If wind conditions allow it, the targeted ship would want to maneuver. For a level attack, the ship would want to minimize its profile by turning directly toward / away from the wyvern. For a diving attack, the ship would want to turn as hard as it can, to maximize the chance of the wyvern missing.
• Part of the crew would be professional archers/crossbowmen on rotating standby. If crossbows are used, regular crew would be assigned to each crossbowman as a reloader to maximize the projectiles fired before impact.
• Naval ballistae (which existed historically) loaded with arrows would be an option to provide a shotgun-like / flak-like attack. However, the author would have to finagle the scenario such that there's enough time to wind it up and its weight would cut into cargo capacity heavily. The historical design couldn't be aimed high enough to counter diving attacks, so that would need to be accounted for as well.
• Ships would want to travel in convoys so that more lookouts are available to detect wyverns and so a struck ship can have its survivors rescued. Cargo might be in buoyant containers to aid in recovery. Supporting fire between ships isn't practical because the weapons available are too short ranged.

Answer 5

Game of Thrones has characters that had a very similar problem (although smaller in scale), and which came up with a very clever solution.

Yes, the dude in the image above is on land, but in the last few episodes they also downed a dragon with such a weapon mounted on a ship.

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Another way to fight off wyverns is through pollution. If you destroy their habitat they will die. As a plus you also get more landing for farming, if they nest on plain terrain.

Answer 6

Stockpile dung pods from various known wyvern species.

When a wyvern approaches, identify dung pods from competing species and have the crew throw them at the wyvern, which will make it assume it's intruding on someone else's territory.