Iron-age humans wish to cross an extremely stormy sea -- one that no pre-industrial vessel humans actually built could reasonably survive.

Here is a graphical guide to some hazards

enter image description here

These people don't have modern materials (titanium, plastic, carbon fibre, etc) but we can fantasize about better natural materials (wood can be more buoyant, ropes can resist snapping) which may provide equivalent benefits in many cases. Any machines must be human-powered.

These people are ingenious so fast-forward the engineering innovations (excluding powered machines) and allow them the benefit of all the hindsight we have.

How could age-of-sail ship designs be adapted to survive extremely stormy seas?


  • the water is deep, so no ground strikes
  • waves are frequently larger than the ship, but not (normally) several times larger,
  • irregular high winds
  • the ship doesn't have to be particularly big, say 100 humans with light cargo only
  • lifeboats don't matter, either the whole ship makes it or nobody does
  • journey of a few days
  • we need propulsion at least intermittently

What design would have the best survival chances?

  • 2
    $\begingroup$ Age of sail ships sometimes failed to survive stormy seas, but frequently did survive, on journeys of weeks or months. The Polynesians travelled and migrated all across the (misnamed) Pacific Ocean in pre-Iron-Age vessels, where the waves frequently were larger than the vessels. On the flipside, in 1998 there were massive losses in the modern, expensive yachts in the 1998 Sydney to Hobart yacht race, so modern design and technology is not always up to the challenge. Given all that, what are you looking for? $\endgroup$ Feb 27 at 21:19
  • $\begingroup$ Noah ark can survive any rouge waves 🌊 but your crews need to dressed up to board it. $\endgroup$
    – user6760
    Feb 28 at 10:06
  • $\begingroup$ So are they trying to cross the sea in one giant ship?... $\endgroup$
    – Questor
    Feb 28 at 22:08
  • 1
    $\begingroup$ Most of this does not apply to small ships, which are/were designed to withstand roll and pitch induced by waves, and were not too heavy to break up under their own weight when lifted by the middle or edges only. And with Iron Age's energy availability, propelling a ship larger than several dozen feet was unfeasible. $\endgroup$
    – Vesper
    Feb 29 at 9:18

3 Answers 3


There are two common ways of building a watercraft larger than a simple dugout canoe: carvel construction, where the hull planks abut each other over a frame, and clinker/lapstrake construction, where the hull planks overlap and are fastened to each other, rather than to an internal frame.

As a general rule, a clinker-built ship is more seaworthy for a given size than a carvel-built one: the lack of an internal frame means that it can flex with the waves rather than smashing through them. The downside to clinker construction is that the lack of an internal frame limits how large they can be.

There's no modification needed to make iron-age ships able to withstand extreme storms. The best-known historic examples of clinker-built ships are the Viking longships. They were used extensively in the North Atlantic -- not a sea noted for its calm temperament -- and generally survived quite well. The largest longship found so far, known today as "Roskilde 6" had a crew of around 100, right around your target size.

  • $\begingroup$ +1, but I think it bears mentioning that the Vikings had another important "technology" for "withstanding" the perils of deep-water sailing in the North Atlantic: a cultural willingness to just incur extreme risk of death. An awful lot of them just died. $\endgroup$
    – g s
    Feb 28 at 7:44
  • $\begingroup$ The long-distance Viking ships used in the North Atlantic were Knarrs, rather than Longships. They are wider, deeper and shorter than longships, and stand up better to weather. $\endgroup$ Feb 28 at 14:55
  • 1
    $\begingroup$ @JohnDallman, the longship is a better match for the OP's requirements: short voyages, the option for oared propulsion, a large crew, and little cargo. $\endgroup$
    – Mark
    Feb 28 at 21:33
  • $\begingroup$ I would add a topdeck to any ship built, so in case of a catastrophic failure that didn't break the vessel straight apart, the crew would stay afloat by virtue of air within. IIRC vikings did not have any on either longships or knarr/knorr (however it's spelled properly). And possibly add human-powered exhaust pump(s) to simplify draining excess water in case of small leakage. Anything harsher and you already need to stop and repair your ship, or plain sink. $\endgroup$
    – Vesper
    Feb 29 at 9:26
  • $\begingroup$ @Vesper, if you can design a topdeck that that is both airtight and will flex with the ship, go ahead. I don't think anyone has ever made one that meets both requirements; during the iron age, I don't think they ever made one that met either. $\endgroup$
    – Mark
    Feb 29 at 21:36


Suggest breaking the ships up into a swarm or making them partially submersible- as in they weather out bad weather beneath the waves.

Basically a submarine, with under water towed container submarines..

  • 2
    $\begingroup$ An iron-age submarine? $\endgroup$
    – Cadence
    Feb 28 at 15:43
  • $\begingroup$ Eh, you can in theory use other substances, like in the civil war. And it has not to dive deep, just out of surface turmoil depth at bad weather? $\endgroup$
    – Pica
    Feb 29 at 7:01
  • $\begingroup$ @Pica, the surface turmoil extends rather deep for an iron-age submersible: 30-60 meters in bad weather. Even the early industrial-age submarines couldn't go that deep. $\endgroup$
    – Mark
    Feb 29 at 21:59
  • $\begingroup$ There were bell divers long before. And sinking to the bottom, waiting for better times on a 60m long hose is hardly submarine stuff. $\endgroup$
    – Pica
    Mar 1 at 7:02
  • $\begingroup$ @Pica, pumping air down a 60-meter hose is well beyond what iron-age technology can manage, and lifting a diving bell off the bottom requires a surface ship rather larger than the bell to get sufficient buoyancy not to be dragged down by the weight of the bell. $\endgroup$
    – Mark
    Mar 9 at 4:08

Simple answer is to just make them Noah's ark.

Whether you believe in the biblical story or not, there has been (at least) decades of scientists and engineers working to support/verify the plausibility of a ship matching the biblical description. The story also specifically says it rained for 40 days and 40 nights, which I would argue constitutes a pretty significant storm. Also, since the Epic of Gilgamesh (which includes the oldest known iteration of the flood story) is twice as old as the Iron Age (around 2500 BCE vs 1200 BCE), you can be sure they would have still had the ability to do so.

enter image description here

  • $\begingroup$ The main issue here is propulsion. Noah's Ark only had to float, my ship needs to get somewhere, in chaotic winds. The oar/sail to hull ratio here is way out. $\endgroup$
    – spraff
    Feb 29 at 10:34
  • $\begingroup$ Noah's Ark has been shown to be plausible in the sense that an iron-age civilization could build one. I don't think anyone has done studies of seaworthiness -- or can. The description in the Bible doesn't cover things like hull shape or ballast, which are critical for determining seaworthiness. $\endgroup$
    – Mark
    Feb 29 at 21:48

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