Let us suppose that at the beginning of the Napoleonic Wars, we have a 5th-rate ship similar in appearance to the 38-gun HMS Lively with a displacement of approximately 820 tons, and a top speed under sail of 13 knots. This class of ship is designed and expected to operate independently.

However, this ship has been built with 2020's equipment to be a type of Q-ship, with the following features:

  • The wooden outer hull is a substantial timber and copper veneer applied over and fixed to a steel hull capable of resisting the naval weaponry of the Napoleonic Wars era.

  • The masts and spars are made from modern steel alloys with a timber veneer.

  • The sails and cordage have been made from modern materials coloured and treated to look like period materials.

  • It has two 18,000 kW engines below its gun deck, attached to reversible variable pitch propellers, capable of propelling the ship at up to 20 knots without sails, or 25 knots under full sail.

  • It has an armament visually similar to that of the period ship, except that the rifled guns are made from modern steel alloys, have a precise bore, and can fire modern ogival high-explosive shells, with attached pre-made cordite propellant, and the guns have a 'flintlock' mechanism that conceals a percussion cap system. The guns' rifling is polyhedral, and has no lands/grooves.

  • There is a small supply of functional period ammunition and powder for the sake of appearance.

  • It carries both openly displayed period small arms, and concealed modern military small arms.

  • It has modern powered bilge pumps.

  • It has a modern desalination system.

  • The interior and exterior of the ship is designed to withstand a cursory examination by naval personnel of the era without appearing particularly unusual, however a detailed internal examination is likely to reveal the hidden modern features.

  • Resupply of modern consumables is not an issue.

How effective might a ship such as this be in combat against genuine Napoleonic Wars era ships? Against what odds would it be capable of prevailing? At what point might period naval personnel notice that this ship is significantly more capable than expected?

  • $\begingroup$ (1) The funnel of that engine will be a giveaway. (2) A modern breech-loading gun is easily distinguishable from a Napoleonic-era muzzle-loading cannon from a mile away. (3) A steel hull doesn't sound and doesn't feel like a wooden hull. $\endgroup$
    – AlexP
    Commented Jan 8, 2022 at 4:19
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    $\begingroup$ I see a time travel tag, does this mean the operators brought this vessel back in time? Do they have some form of base of ops to service the vessel and the resources to repair it? If not, what I always say about the problem with time traveling a modern soldier to the past, after they deplete their initial weaponry they're just a stronger more professionally trained soldier. The even stronger part is iffy. In the case of a ship, even if you have a base of ops to service it, I'm not sure 19th century fuel works. $\endgroup$
    – user93359
    Commented Jan 8, 2022 at 6:31
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    $\begingroup$ Soldiers and sailors tend to pay close attention to enemy strengths and weaknesses in combat -- it's how you stay alive. Sailors and their officers will observer the comparative difference in firepower and armor quickly -- after a couple volleys. Future operations may include a deception plan to draw the enemy's powerful ship out of position, to sink it using torpedoes or mines, or to simply pay spies to burn it out while tied up on the pier. $\endgroup$
    – user535733
    Commented Jan 8, 2022 at 7:20
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    $\begingroup$ @user535733 What the witnesses in battle notice is only important if they make it back home. $\endgroup$
    – Cadence
    Commented Jan 8, 2022 at 8:26
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    $\begingroup$ Seems to me that the ship deception wouldn't last long in real combat... especially if a cannonball hits 'wood' and the steel reveals itself. $\endgroup$ Commented Jan 8, 2022 at 11:46

5 Answers 5


Such a ship would be very effective against Napoleonic era ships. It's effectiveness and the point at which it was noticed to be a superior vessel would depend on the strategy used. The more the speed, maneuverability and fire power were used the easier it would be to spot and restricting such use would risk damage to the ship to some extent.

It's speed would allow it to approach an isolated enemy vessel from any direction it chose and destroy it with ease as it would be able to fire from beyond the range of the enemy's guns. Used in this way its secret might not be uncovered for a long time as the attacked ship could be destroyed before reporting on the opposing vessel.

The same strategy could also be used to destroy perhaps half a dozen or more ships picking one off at a time, but with a larger fleet there would be a danger of getting carried away and getting in too close to enemy vessels. At that point there would be the strong possibility of damage and the need to refit all of the smashed wooden parts. There would also be the possibility of a lucky shot doing some more substantial damage.

It is highly probable that the enemy would spot something seriously wrong if the ship started to use its special abilities to any significant extent.


Almost comically unstoppable

Setting aside the stealth aspects, I'll address the primary questions:

How effective might a ship such as this be in combat against genuine Napoleonic Wars era ships? Against what odds would it be capable of prevailing?

This ship will be practically immune to any and every effort by its enemies to stop it. The most important part here is the armor. With modern steel armor, the cannon shot of Napoleonic ships will be literally useless. (See this excellent question for more detail.)

To illustrate just how useless it will be, let's hit some highlights.

  • The first major battle between ships of the line and metal-armored ships was the Battle of Hampton Roads (also the first ironclad-on-ironclad battle).
  • During the course of the fist day of this battle, the CSS Virginia found itself in conflict with the USS Cumberland, and 50 gun warship, and the USS Congress, a 52 gun warship. Both Union ships were sunk at the cost of... virtually no damage to the Virginia, save for what the ship inflicted on itself by ramming the Cumberland.
  • During the course of the second day, the CSS Virginia exchanged fire with the USS Monitor, another ironclad. They exchanged fire for four hours at near point-blank range, and both left the battle with minor injuries.
  • The armor of the CSS Virginia was just 3-4 inches of cast iron.
  • Armor over the next forty years after that battle would develop so quickly that ships were obsolete before they were even completed.
  • Cast iron was replaced by wrought iron, then by simple steel armor, then the case-hardened Harvey armor, then Krupp armor, then composite alloys and materials. Each of these armors was stronger than its predecessor by a solid margin... and the cast iron was already practically immune to iron shot.

I'd put the odds similarly in favor to Mike Tyson in his prime against a classs room of second graders.

At what point might period naval personnel notice that this ship is significantly more capable than expected?

How long would it take for the enemy to notice? Probably exactly as long as the first broadside within visual range, when all the cannonballs would not just deflect, but simply shatter against the the side of the enemy ship without even making dents, creating explosions of sparks and the tooth-jarring sound of iron on steel.

  • $\begingroup$ It's not totally immune. Since it's faking a sailing ship, rounds can still come in through the open gunports if the hostile vessels reach firing range; there have been recorded instances of this occurring. Moreover, a large number of crew has to working on the deck and rigging to make the illusion realistic and they are therefore not behind armor; one hit from a cannonball or shot will be fatal. $\endgroup$ Commented Jan 8, 2022 at 18:51

I mostly agree with Daniel. But I also agree with Slarty that the use of those capabilities could not be hidden. Some points to add:

  • The auxiliary engine would allow her full freedom of maneuver with just 'fighting sail' or less, yet you scaled it to outrun full sail on a good day. She can run circles around any opponent.
  • Having the sail add five knots to top speed is unrealistic. The best option for a high-speed dash might be to take the top masts down and reduce drag.
  • It would be more than enough (tactically and strategically) if the engines were good for a dozen knots or so. Such an installation would be easy to hide unless some customs inspector goes through the hold.

  • Will there be modern fire control? A gunner's mate pulling the lanyard by eye and gut instinct was unable to hit at extreme range of a smoothbore. Put sensors onto the gun to measure elevation relative to the deck, and onto the hull to measure roll, and fire each gun automatically at the right moment.
  • Even better, take a real modern gun, say 3" or so, and construct a mount that can be disassembled in an hour or so. Some sort of explosive-incendiary shell.

  • Add smallish UAVs designed to look like a bird when you watch them from several hundred metres below.
  • Add slightly larger UAV with laser-guided incendiary bombs.

What I'm describing here is either a commerce raider going after lone enemy merchantmen or very small convoys, or a literal Q-Ship trying to lure enemy commerce raiders. As soon as you get into a fleet battle, word will get out. One ship, even at 20 knots, will not be able to run down all witnesses/survivors of the enemy fleet.

  • $\begingroup$ Actually, adding five knots under full sail was calculated and has been rounded down. I took the base speed under sail of the Lively hull (13 kts) and calculated the effective pulling power of the sails, then added engine power and calculated speed. It came out to 25 and some fraction knots. $\endgroup$
    – Monty Wild
    Commented Jan 9, 2022 at 7:21
  • $\begingroup$ The guns can have modern, automatic aiming packages attached (and can also be loaded with black powder and round shot (shudder)), and the hull has stabilisers. $\endgroup$
    – Monty Wild
    Commented Jan 9, 2022 at 7:24
  • $\begingroup$ As for tactics... it wouldn't be used to attack a fleet during the day... perhaps at night, in bad weather, to pick off stragglers or nibble around the edges of a fleet, using NVGs... $\endgroup$
    – Monty Wild
    Commented Jan 9, 2022 at 7:27
  • $\begingroup$ @MontyWild, I was thinking of tradeoffs for late 19th century ships. E.g. David K. Brown, Warrior to Dreadnought. Also Fred. T. Jane, British Battle Fleet. Most ships could retract their masts, a few would discard it before battle, $\endgroup$
    – o.m.
    Commented Jan 9, 2022 at 11:25
  • $\begingroup$ I am pretty sure you can't just add speed under sail and with engine working to achieve final speed of the ship. The forward motion with engine would interfere with the sails power generation at anything except aftermost winds. $\endgroup$
    – Archelaos
    Commented Jan 10, 2022 at 10:54

Within visual range of the enemy, your ship would most likely be unstoppable. It would need just two modern guns, front and aft. The rest can be decoration.

Napoleonic age ships have a lot of inaccurate firepower on the broadside, but pretty much nothing in the front and aft direction. If your ship has accurate firepower front and aft, it can approach and shoot from afar without presenting its broadside, which means it doesn't even need that much armor on the sides. With the extra speed and no dependence on wind, it will easily outmaneuver them and sink them without them being able to even fire back. For example a 76mm autocannon or something similar loaded with incendiary rounds would probably do the job nicely.

At night, if you extend the 2020 shopping list to night vision equipment, it would be even more ridiculous.

However, in order to hit a target, you must know where it is. Wooden ships probably won't be detected well by your radar, so how will you know where they are? If you don't know where the target is, the fancy ship is useless.

So you would probably stage it as a trap: a large fleet of your ships with the Q ship hidden in their midst. It will be attacked by an equally large enemy fleet and sink them all. Even if there were no survivors, if this happens close enough to a coast, they will send a carrier pigeon and the enemy will know. If it happens within visual distance of a coast, they will also know. This means the secret will be out rather quickly.

You can therefore expect the enemy to update their tactics, and since you disregarded the commonly accepted rules of engagement of the day, they will do the same if sufficiently pissed off. Since your ship can't be everywhere at the same time, they could switch to much smaller fleets, down to one or two boats, and use pirate tactics to sink your merchant ships and cut off your supply lines. Or they could import plague ridden rats in your country, for example.

  • $\begingroup$ Many Napoleonic Wars era ships had chasers - guns mounted to fire into the forward or rear arc. This ship would be no exception. The idea was to make the guns more capable while maintaining visual similarity to period weapons, not to mount and attempt to hide completely anachronistic weapons. $\endgroup$
    – Monty Wild
    Commented Jan 9, 2022 at 10:23

Unlimited food!

/Resupply of modern consumables is not an issue./

Setting aside how formidable a ship would be that never runs out of ammo or fuel, this ship would be even more formidable with its "loaves and fishes" ability to resupply the land armies with unlimited high quality modern food. One could make a case that the ship would be most useful at port, steadily disgorging the limitless modern consumables it can produce which would then be taken inland to the armies (British and otherwise) that actually won the Napoleonic wars. Not to mention hungry people displaced by the fighting who would be even more appreciative than soldiers.

In fact, sales of this unlimited food early in the war would be able to subsidize the war effort in every other respect. The modern consumables would likely include items like Twinkies, Spam and CocaCola which would fetch luxury good prices in Europe and Britain. If "consumables" also includes modern drugs like penicillin, spinosad and sildafenil the profits would be even more astounding. This awesome ship could win the war without even firing a shot!

  • $\begingroup$ Not that unlimited... reasonable resupply of uptime consumables, not wholesale supply of locally-available goods. $\endgroup$
    – Monty Wild
    Commented Jan 9, 2022 at 5:09

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