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Sails were good, they made ships go farther than ever before, relieved them of the critical necessity of oars, and with the right design they could even sail into the wind.

However, sail ships have the one weakness that without wind's aid, they're no better than a floating wooden log stranded on the sea. Imagine now a naval power that inhabits an island that is definitely not windy, and for the survival of their nation they need a strong, and fast navy that can sail out of their island at a moment's notice, and maintain their speed at sea at every situation.

Originally I planned on having ships propelled by paddle wheel powered by humongous 4 armed golems, but I don't think there would be enough golems for the navy and I'm trying to keep magic involvement at a minimum. I also thought of using good ol' oars, but they are slow (I mean, trained oarsmen could make a trireme reach speeds of 9 to 12 knots, your average age of sail ship could do 14 to 16.5), they require a lot of manpower (which also means that more supplies are needed), and they can't function during long stretches of time (those oarsmen need sleep and rest too).

Limiting technology to pre-19th century (Not really, but avoid things like coal, industrialism or steampunk), would there be any design that can effectively propel a ship at "fast" speeds without the aid of wind?

Notice - Things such as paddle wheels, oars, waves, steam or even a little bit of (logical) magic are not completely ruled out, it's only that I feel they wouldn't be effective enough without either advancing technology or being under very specific situations, though I might be (probably am) wrong about this assumption considering how much of an air head I am.

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    $\begingroup$ So you forbid wind, oars, steam and anything post 19th century? That includes all power sources humanity learned to use, doesn't it? $\endgroup$
    – Mołot
    Jan 27, 2018 at 23:20
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    $\begingroup$ Donkey-power! The over-the-horizon smell would make it a truly offensive force. However, a huge and vulnerable logistical tail is required to feed ungulates regularly, so it's not going to be an ocean-spanning force. $\endgroup$
    – user535733
    Jan 28, 2018 at 1:57
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    $\begingroup$ @kikirex Not enough magicians to go around. Some ships can use magic indeed, but even then I'll need to explain how the magic works. $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:38
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    $\begingroup$ It would be interesting to see your research on the speed of sailing ships. You seem to be taking some relatively modern statistical outliers and assuming they are typical of the entire age of sail. See econstor.eu/bitstream/10419/109720/1/786607629.pdf for a contrasting point of view, with actual data. $\endgroup$
    – David K
    Jan 28, 2018 at 18:35
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    $\begingroup$ Are propellors ruled out? The first practical propellor was demonstrated in 1775. $\endgroup$
    – Joe Bloggs
    Jan 29, 2018 at 7:38

19 Answers 19

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Better oars, or paddle wheels propelled by "oarsmen".

Without steam, the only power sources available to you on the open water are muscle, wind, and magic. And you've ruled out wind and magic, so...

(Well, to be fair, there's also wave power--but if there's not much wind, there won't be much in the way of waves, either, and wave power is not going to get you up to 9 knots, let alone 16.)

So, you've gotta use muscle power, and figure out how to do it more efficiently than having rows of guys pulling oars. Or at least, more efficient than rows of guys in a trireme pulling oars.

Triremes had fixed seats for the oarsmen. That's not optimal. Modern racing shells, and rowing training machines, have sliding seats, so that the oarsman can engage essentially every muscles in their body to move the oar; you start coiled up, arms extended, with the seat forward, and then simultaneously push back with the legs (moving the seat), lean back with the torso, and pull with the arms. So, you could probably significantly boost your peak speed just by adding sliding seats.

Moving an oar actually wastes quite a bit of effort, though, on the backstroke. All of the energy used to hold the oar out of the water and move it back to its starting position is just wasted. So, if you could find a way to avoid that, you might be able to get higher speeds even without maximal muscle engagement.

Paddle wheels give you that. They don't have any recovery stroke. I couldn't find any references directly comparing paddle to oar efficiency given the same power input, but paddle-wheels are generally less efficient than propellers, and modern oars can be nearly as efficient as propellers (although, see An application of paddlewheel propulsion to a high speed craft; it's entirely possible that the poor relative performance of paddle-wheels is just because we stopped developing the technology before its peak!), so oars might still be the best option... but paddle-wheels could win out if they let you get more consistent power output from your "oarsmen".

Theoretically, you could just replace oars with cranks, and still use oarsmen on sliding seats to pull them to turn a paddle wheel. I'm not sure that would really be the best use of the "whole machine" (mechanical parts + human power plants), though, in addition to being somewhat complicated. The simplest approach would be to have your "oarsmen" run in treadwheels, which can be directly (or nearly so--perhaps with a slight gear / pulley ratio) coupled to the drive paddles. That would make optimal use of the human body for sustained mechanical power output (after all, we are evolved specifically for high-endurance, long distance running!), even though it sacrifices some potential power that oars can extract from the arm muscles.

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    $\begingroup$ That was surprisingly fast! I suppose wind is still of paramount importance for the ships, but with the sliding seats and paddle wheels you suggested, these ships won't be stranded on the coast at the sluggish speeds. My sincere thanks, I want to mark your answer as the definite one immediately, but the mods told to wait 24 hours before declaring a question answered. $\endgroup$
    – Jedboo
    Jan 27, 2018 at 23:44
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    $\begingroup$ "...it's entirely possible that the poor relative performance of paddle-wheels is just because we stopped developing the technology before its peak" - no. A paddle is inefficient because it spends only a small amount of its rotational period in the optimal position for providing thrust, and a large amount of its rotational period doing little of value. Part of the time it tries to lift the ship out of the water, part of the time it tries to pull the ship down INTO the water, and the rest of the time it's dead weight. Propellers are much more efficient because they always provide thrust. $\endgroup$
    – Bob Jarvis - Слава Україні
    Jan 28, 2018 at 14:10
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    $\begingroup$ @MatthieuM. Propellers are much more complex technology. Naive designs with flat, constant pitch blades (like a ceiling fan) are really crappy, and driving them requires either developing rotating, water-tight joints through the hull, or using belt drives outside the hull, which wouldn't be terribly reliable. Building efficient propellers, and systems to drive them from within the hull, are things that could be done with Age of Sail materials and tools if they knew how, but figuring it out is a bit of a leap, and it doesn't seem to quite fit the aesthetic, as Eth's comment notes. $\endgroup$
    – Logan R. Kearsley
    Jan 29, 2018 at 15:23
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    $\begingroup$ I wouldn't declare premature defeat for oars. Without modern methods of hydrodynamic design, all your propulsion methods will have significant inefficiencies due to paddle/blade shape, and then there are the substantial friction losses in the bearings for paddlewheels or propellers. The small fraction of the rower's energy that goes into lifting the oar and returning it to the starting position may be a small price to pay to avoid the problems you'd encounter with any alternative. $\endgroup$
    – David K
    Jan 29, 2018 at 18:24
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    $\begingroup$ Don't forget the importance of a flywheel; it lets you store energy and release it without having your "oarsmen" speed up/slow down in sync. $\endgroup$
    – Yakk
    Jan 29, 2018 at 19:30
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You can use muscle power and go very fast. But not human muscles.

orcas

http://www.nmfs.noaa.gov/pr/species/mammals/whales/killer-whale.html Anyone who has visited Sea World will have been impressed that very large and powerful ocean animals can be trained. A pack of orca could easily pull a boat at great speed. I feel like I saw 2 whales with hoops on their noses pull a trainer in a small boat but I cannot find an image. An unladen orca can swim at 35 mph. Your people have tame killer whales (or false killers, or pilot whales, or fin whales if you want more awesomeness. Or maybe a mix.). Teams of whales pull the ships like chariots.

If you want more variety, you could include some giant seals doing chariot duty. Leopard seals are intelligent, grow to 9 feet long and are as fast as killer whales.https://oceanwide-expeditions.com/to-do/wildlife/leopard-seal

leopard seal http://honesttopaws.com/wp-content/uploads/sites/5/2016/05/leopard-seal.png

Big fish, sirenians, giant squid - for a work of fiction you could use any of these. Your boats will be fast and it will be awesome.

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    $\begingroup$ This is an extraordinary workaround! With enough whales a ship could easily outrun even the most effective of sails. Though the coordination of whales, their procreation, the amount of supplies they'll consume and overall the logistical nightmare it would be to keep hundreds of whales on a port might be a problem. This is an excellent idea, thank you very much! Some flagships belonging to kings or powerful nobles would definitely be a lot cooler being pulled by sea serpents or other mystical beings! $\endgroup$
    – Jedboo
    Jan 28, 2018 at 3:23
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    $\begingroup$ Think of the logistics of keeping hundreds - or thousands - of war elephants. Seleucus' wars took him as far as India, where, after two years of war (305-303 BC), he made peace with the Indian Emperor Chandragupta Maurya, and exchanged his eastern satrapies in the Indus River Valley for a considerable force of 500 war elephants.. If you give your enemy 500 war elephants how many do you keep? $\endgroup$
    – Willk
    Jan 28, 2018 at 17:30
  • $\begingroup$ Yeah, or have dragons pulling the ships. Feeding becomes a non issue for whales as they will eat where they sleep. Finding the right level of magic to control the whales will be the key. $\endgroup$
    – KalleMP
    Jan 28, 2018 at 20:31
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    $\begingroup$ @KalleMP - I think you would need to feed the whales. Just as one could not expect war elephants at high density to successfully forage for themselves, so too you would need to bring food for your war whales. Which would also serve to tame them without magic (like SeaWorld!). $\endgroup$
    – Willk
    Jan 28, 2018 at 21:14
  • $\begingroup$ @Will Christ my friend, after that elephant example I'm reassured that logistics wouldn't be as big as a problem as I thought it would be $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:17
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You are underestimating the value of oars

Oar powered ships were faster than sail powered ships for all of recorded history. If they were not, then they would not have been used once sails were invented. On the occasion, in great sailing conditions, with a specially designed ship (i.e. a clipper ship), a sailing ship could reach up to 15 knots, or even more. But this was not typical.

The Mayflower averaged 1.7 knots in its 66 day journey across the Atlantic in 1620. The Royal Greenwich Library says that studying old copies of Lloyd's List yields Liverpool to New York times of around 21-29 days; or 4-6 knots. This was in 1818-1832; just before the first steamships came online.

If all you have to beat is 4-6 knots, you can do that with oars. Its just more expensive to feed and house so many slaves, and it cuts down on your cargo space and weight.

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    $\begingroup$ What you said is there is all factual, but I'm afraid that the oar ships in comparison are certainly smaller and lighter, aren't they? I believe that ships of the line, or galleons, were much larger and heavier than ships propelled by oars. Caravels for instance, can regularly maintain speeds of 8/9 knots. I think that crossing the Atlantic on a ship as heavy as the Mayflower using oars would be slower than using sails, after all, oarsmen cannot propel during the entirety of the day, I think that they could at most propel it only for three to four hours every day, and not at maximum speed, $\endgroup$
    – Jedboo
    Jan 28, 2018 at 3:11
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    $\begingroup$ (continuing the last comment) while the sail ship can sail during the whole day (and night, if necessary). However, you have proved that a ship can use oars as effectively as sails, and if the circumstances demand so, they might even be more effective, and I have to thank you for that. Also, a fun fact about oar ships is that many civilization which employed them em masse (such as Athens and Rome), preferred not using slaves as oarsmen, instead they used professional trained oarsmen, as it turns out, they can propel the ship much faster than slaves or untrained men. $\endgroup$
    – Jedboo
    Jan 28, 2018 at 3:15
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    $\begingroup$ WRT the Mayflower, I believe that was well before the Gulf Stream was well known. (It was charted by none other than Benjamin Franklin.) So taking the obvious route from Britain to Massachusetts, they'd have been fighting a current of ~5 kts most of the way. $\endgroup$
    – jamesqf
    Jan 28, 2018 at 4:49
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    $\begingroup$ The cost of crewing oared vehicles meant that only lighters, warships, and river-going craft were equipped for primary oar power once sails were at all good. And once cannon came on the scene ramming tactics were deprecated so rowed warships rapidly disappeared. $\endgroup$
    – dmckee --- ex-moderator kitten
    Jan 28, 2018 at 17:55
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    $\begingroup$ Oars also added maneuverability, which sailing ships did not have. You can find some discussion of this in Mahan, especially where he is speculating about the likely effects of steam power. $\endgroup$
    – fectin
    Jan 28, 2018 at 21:57
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What about a series of known (or unknown) surface water currents?

Surface currents could be mapped or tied to a lunar cycle, and easily utilized by a society. It sounds like you're aiming for a island society that is militarily powerful, so their islands could be at a crossroads or nexus of currents. From that geographically superior location they could maintain trade and military power easily.

It doesn't allow for fast travel outside of the currents, but I think it may fit into your technological needs better.

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  • $\begingroup$ You presumed correctly, the island nation I'm talking about is a sea faring militaristic country, and you made an excellent point with the water currents, but if I'm not mistaken, shouldn't water currents be tied to wind currents? Meaning that if there's a lack of mighty winds in a certain coast, shouldn't it be the same for water currents? $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:56
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    $\begingroup$ @Jedboo - currents are tied to two things. temperature gradients, and salinity gradients. Not related to the wind (to any significant degree). Essentially, water heats up at the equator, starts moving to the poles (along the surface because warm water floats on top of cold water) and then sinks as it cools. when it gets near the equator. The mouths of rivers are a source of fresh, non salty water, which floats on top of more salty water. Check en.wikipedia.org/wiki/Thermohaline_circulation for more detail $\endgroup$
    – Scott
    Jan 29, 2018 at 1:03
  • $\begingroup$ @Scott I stand corrected then. I see now that currents are a useful thing in this circumstance, they might be a limited or situational method of propelling, but they're definitely effective and will do the trick. Thank you both $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:30
  • $\begingroup$ Could also be amusing if some of the currents would smash ships into rocks/land/reefs. This way you need to be experienced with sailing in the area to navigate safely, preventing invasions $\endgroup$
    – phflack
    Jan 29, 2018 at 14:22
  • $\begingroup$ @phflack Christ, that's a true danger that I did not take into account. Though I'm sure it wouldn't be too different than the wind dragging a ship into a reef or rocks, it definitely be more dangerous and risky. Thanks for the warning $\endgroup$
    – Jedboo
    Jan 29, 2018 at 18:00
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Change your hulls

The shape of the hull is one of the endless compromises of designing watercraft. You get to choose between wide and stable, long narrow and fast, short and manoeuvrable, chunky and high capacity. There are other options, you can have long wide fast ships, catamarans and trimarans. These multihulls are significantly faster and more stable than the equivalent monohull ships, what they lack in return is manoeuvrability.

It's not an unknown concept in the period, but was mostly used by the Polynesians and tribes using outrigger canoes rather than on the larger scales we now use the designs.

A nation using rowed multihulls would easily be able to outrun a navy using monohull sailing vessels in a region with low winds and with fitted rigging would still be faster in the water under sail. enter image description here (http://www.hokulea.com/)

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  • $\begingroup$ Thank you for the answer, catamarans and trimarans are a genius creation, but in this occasion they might not fare too well, see, the question here is about a sea with a insignificant wind, or none, and it seems to me that trimarans and catamarans are highly effective on low winds, but they're as stranded on the sea as any other sail ship would be without wind. $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:34
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    $\begingroup$ @Jedboo, you can still row them, but you can row them faster. In the picture you can see a platform down the outside, that's so you can treat it like a big canoe and everyone can get out and paddle. $\endgroup$
    – Separatrix
    Jan 29, 2018 at 8:02
  • $\begingroup$ Oh, I see now. Do you think it'd be possible to build larger scales of this ship? $\endgroup$
    – Jedboo
    Jan 29, 2018 at 18:01
  • $\begingroup$ @Jedboo, they scale up well but they suffer from a shortage of hold space, what they gain instead is lots of open deck $\endgroup$
    – Separatrix
    Jan 29, 2018 at 20:26
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An improvement on the answer by Logan R. Kearsley would be to have the men sit on stationary bikes connected to shafts that turn propellers. A metallic shaft turning metallic propellers would be stronger and sturdier than a set of wooden paddle wheels which were easily damaged by strong waves at see.

Man powered paddle wheel boats and ships were used for hundreds of years by the Chinese, and as far as I know they were mostly used on rivers and lakes and near the coasts. I am not an expert on Chinese naval history but as far as know man powered paddle wheel ships were not used much at sea.

http://www.cogandgalley.com/2009/10/chinese-paddle-wheel-ships.html1

There was massive use of both paddle wheels and screw propellers on 19th century steamships and the result of decades of comparison is that paddle wheels were gradually phased out for ocean going vessels and reserved for river boats. Both side wheels and stern wheels were used for river boats but ocean going vessels seem to have almost entirely used side wheels or propellers.

Furthermore, wooden paddle wheels were easy to damage in battle. And 19th century warships found that side mounted paddle wheels interrupted the long lines of gun ports on their gun decks. Eventually the many smaller guns on gun decks and poking out though gun ports were replaced by much fewer and many times more powerful guns in gun turrets above the main deck. After that side wheels would not have limited ship's armament. But by then ships were much more advanced than your "age of sail" requirement and steam engines would have been invented.

Thus man powered propeller ships may be superior to man powered paddle wheel ships.

And some consideration should be given to domestic animal powered ships.

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  • $\begingroup$ That was a fine addition! The example of paddle wheel you showed me seem to be excelente when used on rivers and lakes (though as the link you provided itself states that Romans knew this technology, but did not use it, because it wasn't effective on seas such as the Mediterranean). $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:50
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Oared ships are the age old solution, but leave a lot to be desired. Ancient galleys required lots of skilled oarsmen packed into a fairly small space to generate enough energy to achieve sprint speeds or to execute complex manoeuvres. This leaves very little room for supplies, which is one of the reasons oared galleys rarely sailed out of sight of land and beached at night, so the crews could get out and forage for fresh water, perform bodily functions and so on.

enter image description here

Ancient Greek trireme

In order to maximize the efficiency of muscle power, the ship was also very lightly built, almost like a modern racing shell. Barry Strauss, in his book "Salamis" suggests that triremes were so lightly built the Greek marines on board remained seated on the deck during battle to keep the ship from being upset.

The modern view of heavy, lumbering galleys using enslaved oarsmen is more recent. The Spanish conquest of the New World allowed vast quantities of silver coinage to enter circulation, unleashing a wave of inflation. Skilled oarsmen were too expensive to maintain, so the Spanish took to impressing criminals and slaves as oarsmen, using the galleys as giant artillery platforms and filling the upper decks with troops. (As a counterpart, the Serenìsima Repùblica Vèneta retained skilled oarsmen, using them as extra troops when boarding enemy vessels).

enter image description here

Model of a Venetian Galley of the 1500's

As for your question, polymath Leonardo da Vinci had sketched out several inventions in the late 1400's which anticipate modern self propelled boats and ships. For example, he designed a gear mechanism to provide mechanical advantage for powering a paddle wheel (the image is not clear if there is a crew supposed to crank this or a wound spring):

enter image description here

Leonardo's Paddle Wheel

Of course Leonardo considered naval applications as well, including a gunboat and a submarine:

enter image description here

Leonardo's gunboat

enter image description here

Leonardo's Submarine. The bags control buoyancy and a pair of flippers in the rear provide propulsion

The largest issue prior to the industrial revolution is while you can have mechanical paddlewheels or flippers, the energy density of humans or mechanical power storage (springs) is limited, thus limiting your range and ability to sustain operations.

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  • $\begingroup$ And the vikings could easily get 9 knots out of oarsmen who where also kept in shape for fighting. $\endgroup$
    – boatcoder
    Jan 29, 2018 at 18:13
  • $\begingroup$ Vikings also used the wind to their advantage whenever they could. $\endgroup$
    – Thucydides
    Jan 29, 2018 at 21:17
  • $\begingroup$ True, but they could move upriver where sails don't work well at all. Sails are really only good on open bodies of water, not in confined places like rivers. I know, I've sailed in both places and getting useful wind on a river is rare. $\endgroup$
    – boatcoder
    Jan 30, 2018 at 21:38
  • $\begingroup$ It is also situational. The ancient Egyptians used sails to go up the Nile, and drifted with the current going down the Nile. Large rivers like the St Lawrence can be navigated by sail as well, but requires a lot of skill to do so. $\endgroup$
    – Thucydides
    Jan 30, 2018 at 21:40
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Rotor ships. A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled by large vertical rotors, sometimes known as rotor sails.

This method of propulsion could be used by a society of any level of technology, as it does not require anything more than the ability to rotate the tubes.

enter image description here

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    $\begingroup$ Unfortunately, the rotor sails have to be rotating to generate the required effect. Today this is done with electric motors, with power provided by a (relatively) small electric generator - 50hp in the first rotor ship. Also, from the Wikipedia article, "Despite having completed trouble-free crossings of the North Sea and Atlantic the power consumed by spinning 15m tall drums was vastly disproportionate to the propulsive effect when compared with conventional screws (propellers)". Or, in other words, there ain't no such thing as a free lunch. :-) $\endgroup$
    – Bob Jarvis - Слава Україні
    Jan 28, 2018 at 14:23
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    $\begingroup$ That was a good answer, but as Bob Jarvis explained, I'm afraid I cannot use it, but thank you for answering. $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:41
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    $\begingroup$ Not only do the rotors have to be spinning, they need relative wind to work, so they're no different from sails: No wind, no move. $\endgroup$
    – jamesqf
    Jan 28, 2018 at 20:04
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Put together oars as propulsion and catamaran as hull design.

The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes.

At low to moderate speeds, a lightweight catamaran hull experiences resistance to passage through water that is approximately proportional to the square of its speed. A displacement monohull, by comparison, experiences resistance that is at least the cube of its speed. This means that a catamaran would require four times the power in order to double its speed, whereas a monohull would require eight times the power to double its speed, starting at a slow speed.

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    $\begingroup$ A great idea, but wouldn't the catamaran need to be made much heavier and larger to host the oarsmen, thus losing it's advantages? $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:46
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    $\begingroup$ A Polynesian war canoe, then. $\endgroup$
    – τεκ
    Jan 28, 2018 at 22:31
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If your interest is in warships rather than cargo ships then you can get way with a design that does not need to allow very large changes in displacement, and for efficiency (hence speed and endurance) and stability (hence a stable firing platform) I offer you the Small Waterplane Area Twin Hull vessel design.

Two hydrodynamic submerged hulls provide buoyancy, with low levels of wave-induced drag at a range of speeds. Waterproofing by virtue of being filled with foam?

For propulsion you absolutely cannot beat propellors, and the depth of the SWATH hull helps cut down on cavitation due to poor design. If your technology rises to it you can have pedal power and perhaps an energy storage system (pneumatics?) to give that little extra burst of ramming power.

Frankly, neither oars nor paddles are ever going to be as efficient as a propellor, and a displacement hull (of which a catamaran is just a variant) is always going to suffer from higher wave drag and lower stability.

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  • $\begingroup$ Dang, that's a fine hull design! My only fear is that it may be not be built with materials and resources of the age of sail, but thank you for the information. I'll keep that in mind. $\endgroup$
    – Jedboo
    Jan 29, 2018 at 17:58
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Wings.

If the sails are free to rotate on the vertical axis, they can be used as fans or wings, and propel the ship. This could be easily done on windsurfs even if the sail isn't really optimized to do that (moving the sail on the upbeat has always been a pain, to me at least; half the energy gets wasted, or that's the impression anyway).

If you had a double- or triple-hinged sail, it could better simulate the 'fishtail' movement of a wing, and make better use of the power.

The wing naturally evolves from just beating a normal sail to manoeuver in a low wind, to a sail that does it twice better by being able to 'fishtail', to a sail that beats more or less like a bat's.

When there is a little wind, the ship is however capable of exploiting it to the fullest.

The necessary energy for no-wind sailing would still need to come from golems, though; with windsurfs, the "engine" has the same weight of the boat or more, and this wouldn't change much when scaling up. So using man- or beast-power would almost certainly be unfeasible.

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    $\begingroup$ A fine and creative answer, but aren't wings less effective than just regular oars and paddle wheels, not to mention depending on the material they're built with, such as sail, they might be too frail to endure ocean waves and water. $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:29
  • $\begingroup$ @Jedboo absolutely. I was trying for 'spectacular' :-). For efficiency, flexibility and robustness, paddle wheels are likely the best option - according to Mark Twain you can even crawl on some sandbars with them. $\endgroup$
    – LSerni
    Jan 29, 2018 at 9:55
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It doesn't really matter.

This hasn't really been addressed in other question, while they have provided plenty of options.

What I mean is that any advancement's will be mirrored by any naval power in your world. Or at least should be. So even if you have only inefficient oars, probably everyone will have them. If you have Golmn powered oars, everyone will have them. That's of course assuming the windless-ness will affect everyone on equal terms.

We'll assume by this:

Imagine now a naval power that inhabits an island that is definitely not windy

Means that areas away from the island are normal. And that the lack of technology makes sailing still a viable method of propulsion outside the island.

Now, imagine attacking the Island nation. Would you use sail only ship? Probably not right, so you would use whatever is currently the best option. If you went to attack them and you had oar ships and they had paddle boats and whopped the tar out of your navy, the next time you would probably have your own paddle boats. If the Islanders had more efficient hull designs, you would see that and quickly copy the design.

Basically it would be an arms race. Well, assuming the island was valuable enough. Otherwise you would just avoid them.

From both a defense and offense point of view, there some considerations to make.

  • Outsiders would need dual propulsion ships to attack.
  • Islanders would need dual propulsion ships ships to attack
  • Outsiders could defend with only sail powered ships
  • Islanders could defend with only non-sail powered ships

Ships that have to be both sail and non-sail are at a disadvantage to those that are just one propulsion method. Generally there would be less space for guns and less space for fighting men. You wouldn't send your oars men ashore in an attack because if they got killed you whole navy is lost.

I am assuming too that sailing from the island to anther land mass would be more efficient by sail then by oar ( for instance )

Otherwise I really like some of the other Ideas quite well.

My preference would be something like a hamster-wheal powered screw ship. But instead of hamsters I would use what ever animal is the lightest and fastest available and preferably only found on the island. Such as ostriches or some other animal that excels at high speed or long endurance running.

An interesting plot point could be if the best runners to power the ships only existed on the island. This would provide them with a sight advantage if they could maintain exclusive control of this resource. There could be some neat espionage stuff too.

Otherwise things will tend to reach parity.

One Idea I did have the concerns magic, is if you allow enchantments. Then magic can be used that does not involve active participation of the spell-caster. What form of enchantments could vary from some kind of "magical" engine, to harnesses to control sea beasts. Even a jar of wind or something like that ( something similar to this was used in Homers Odyssey )

Odysseus and his crew stayed with Aeolus, a king endowed by the gods with the winds. He gave Odysseus a leather bag containing all the winds, except the west wind, a gift that should have ensured a safe return home. Just as Ithaca came into sight, the greedy sailors naively opened the bag while Odysseus slept, thinking it contained gold. All of the winds flew out and the resulting storm drove the ships back the way they had come.

That gives me another odd idea for a story, what if the magicians secretly enchanted the island and stole the winds, just so they could sell it back in small amounts to the populous ... lol

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  • $\begingroup$ You have quite a huge deal of insight on arms race, but let's take an example on the British, during the age of sail, they alone (and maybe Portugal) knew the medical effects of citrus over scurvy. They had this magnificent secret well kept, and the same was true for many of their shipbuilding technics and naval experience. As it turns out, not only reverse-engineering was kind of primitive back then, as most of knowledge on maritime business relied on experienced seamen, who didn't often reveal their nation's secrets $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:24
  • $\begingroup$ Also, I think you might have missed the main point here, the main concern of the islanders isn't about building a unique navy that has an edge over all others on their coast, their main concern is leaving and sailing at their coast. With only sails and oars, their speed and effectiveness are sluggish and poor on their coast. The military isn't the only institution concerned with this situation, merchants, fishermen and other people are too, and they definitely don't mind if other nations understand how to sail with no wind. The main point here is building a ship design, not a top state secret. $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:27
  • $\begingroup$ @Jedboo - I don't disagree with you on anything you said, I just didn't see it discussed and thought It was relevant and there were plenty of other good ideas for the "means". So it's not an answer so much as somethings I thought worth mentioning. I liked the animal chariot ones especially. IF you allow enchantments then magical harness could be made for them, this would require less active participation by wizards, as they could enchant the devices and go about their business. $\endgroup$
    – ArtisticPhoenix
    Jan 29, 2018 at 4:31
  • $\begingroup$ Oh, I see now, sorry then, the things you said were indeed mention-worthy, and you have made me aware on naval ship race situation that I had been ignoring for too long now. It'd be great if more people saw your answer and shared their conclusions too. Thanks for the answer. $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:42
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If it's only about going off the island, you could have long ropes under water with huge counterweights attached on pulleys beyond the shelf. These counterweights would be pulled towards the island when not needed, and if they need to leave the island quickly, they could just attach the ships to one of the ropes and release the weights to pull the ships really fast (depending on weight to drag ratio) to the open sea.

If it's then about navigating the sea, a current sail might work. Currents move in different velocities in different sea depths, so using the right mechanics, you could build a sail that works with water currents instead of wind.

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  • $\begingroup$ Welcome to WorldBuilding Leo! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Jan 29, 2018 at 13:29
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I believe that in one of the last novels in his Safehold series, David Weber had “crank galleys”, which were essentially galleys in hull configuration, but driven by propellers rather than oars. The propellers were manually cranked by the ‘oarsmen’. Think of the propeller as being the ‘business end’ of a brace-and-bit with the ‘brace’ being extended for the length of the ship, and alternating on sides of the centerline.

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Blow air bubbles under the ship at speed. This is air lubrication and reduces drag 20%.

https://www.sciencedaily.com/releases/2016/09/160902125334.htm

If they can make fast burning material like gunpowder the can use rockets. If they can distil highly volatile oil from plants to use in some rocket thing (which is controllable).

There is a heat differential powered by solar, hang gliders harvest it as well as wind. Can't think how a ship could harvest it except for being towed by glider. One could make it larger by burning fuel on-board or capturing heat from the sun. Towed gliders would be good for keeping lookout.

There is also wave power. See https://www.liquid-robotics.com/wave-glider/how-it-works/. Perhaps more useful would a well deck at the rear that something floats up and down on a pivot moving a flipper behind the ship.

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In addition to the answers already posted in this thread:

If you want to avoid using magic, industrial power applications or manpower, you could resort to other on-deck muscles. Have a set of wheels turned by oxen or other large herbivores, and control the power output with a gearbox or by making the oxen go faster. This has an advantage over being pulled by marine animals on a leash, as animals outside the ship are harder to control (leash vs lever), easier to spot and kill by the enemy, and reduce maneuverability (huge turn radius vs on-spot turning).

Obviously, this option is only for larger ships with paddle wheels or propellers, able to have at least one such turnwheel, oxen, and food supply for the animals. Smaller ships would likely still rely on oars.

If you want to cut out the middleman: The book Monster Blood¹ describes a setting where ships and other vehicles are powered by muscles, but not animals or humans. The vehicles contain tanks with artificially grown muscles connected to a crankshaft, and can be regulated by increasing or decreasing the nutrient supply to the tank. The book never really goes into detail about this technology, it might be a good concept to explore for you.

¹Will add source when I'm not on mobile

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  • $\begingroup$ That was a magnificent answer, animals powering paddlewheels could triumph on the seas over the lack of wind. They'll take a small toll on the supplies, but likely nothing compared to a legion of oarsmen. Thank you, $\endgroup$
    – Jedboo
    Jan 28, 2018 at 15:53
  • $\begingroup$ @Jedboo: Just so you know, something like this has actually been used for transport upriver. Google around a little bit and you'll find diagrams. $\endgroup$
    – Random
    Jan 28, 2018 at 23:52
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    $\begingroup$ @Era Oh yes, I did a bit of googling and found out the Romans were quite fond of this technology. They had everything figured out, hadn't they? $\endgroup$
    – Jedboo
    Jan 29, 2018 at 4:18
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For fast travel without wind, it's hard to beat good old-fashioned rockets for pure speed. Ships could be equipped with two sets of rockets: one for "boosting" from the island out to the windy part of the sea, and the other for the return trip. Use sails for normal propulsion, and rockets to bridge the windless gap. Also useful for catching up with fleeing enemy vessels, or just scaring the living daylights out of them. You can tweak the designs to get both long, slow burns or sudden bursts of speed.

Rockets have been around for millennia but not frequently utilized because their physics were not well understood. Perhaps your civilization has dedicated considerable time into their study and have perfected the art. Your biggest challenge would be fuel (balancing fuel volume with burn time, thrust produced, distance required, etc). Perhaps as part of their research, your civilization has discovered how to create or harvest the necessary fuel out of a material unique to their island.

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It is a misconception that a sailboat requires moving air to sail.

All sailboats derive their energy from the difference in speed between the Air and the Water, so if both Water and Air move at the same speed there is no energy available to do anything other than "float" with the current.

Conversely if the water is moving and the air is stationary, there is a delta between them that can be exploited to move the boat.

A modern Americas cup sailboat can easily move against the current with no wind. Here's the link to to designers discussing it:

https://www.youtube.com/watch?v=WBG1g8s3BT0#t=8m40

The example he sites is on the Amazon river with a 12 knot current. Specifically he states the boat could move against the current at twice that speed.

Note: It is only with modern "foiling" sailing boats that the energy can be extracted efficiently enough to make sailing without wind possible (the boat has to be able to sail significantly faster than the differential speed in order to navigate against the water current.

I am not clear on what technology you are allowing, but if you have modern materials (carbon fiber) and your world has predicable water currents you can have sailboats that can navigate with no actual wind.

Note: The water currents create an apparent wind, due to to the boat moving through still air - in the same way as you feel a breeze on your hand if you wave it about.

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    $\begingroup$ So, following your logic, a sail boat in a water current heading N at 5 km/h with a wind blowing N at 5 km/h should not move? $\endgroup$
    – L.Dutch ♦
    Jun 15, 2018 at 11:02
  • $\begingroup$ Are you the same David who posted this answer on a similar question? If so, glad to see you signed up for an account! The mods might be able to help you merge your other answer into this account. $\endgroup$
    – F1Krazy
    Jun 15, 2018 at 12:39
  • $\begingroup$ L.Dutch - No it would move at 5 Km/h north, the lack of energy I am sighting is the energy to do anything other than float with the current. For example the boat would have no steerage to be able to turn or move in any way except as the current pushes it. @F1Krazy - Yes I wasn't able to add anything to my original answer so I tried to explain the answer to a similar question. $\endgroup$
    – David
    Jun 15, 2018 at 16:08
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  1. Propellers

It shouldn't be too difficult to make a multi-person crankshaft. The propeller shaft doesn't have to pass through the hull. The propeller can be carved from wood.

  1. Octopoid propulsion

Octopus inspires silent propulsion system for boats and subs - https://newatlas.com/octopus-squid-propulsion-system/28135/

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