I attended a Maritime college, and while I'm not a marine engineer (I studied the deck operations side of things) I can tell you that the biggest problem with a wooden ship the size of the ark isn't the design, its the structural strength of the wood.
Ships have a lot of forces acting on them, even in calm waters. They depend on their buoyancy being fairly evenly distributed. Wave action will cause one or both ends of the ship to be lifted, resulting in the buoyancy of the center to be reduced, since the water isn't supporting it as much. This is known as "sagging". As the wave moves down the hull, it lifts the center, reversing the stresses. Now the bow and stern have reduced support, a situation called "hogging". This repeats over and over, with every wave that passes the ship.
Wood construction vessels have a practical limit as to how long they can be. The longer the vessel, the greater the stress. Wooden vessels longer than 300-400 feet have serious problems in waves. A 450' wooden barge could simply not be built strong enough to withstand the stresses of hogging and sagging. Wood just isn't that strong.
From my reading, the largest galleys mentioned to support the claim of wooden ships the size of the ark were not actually as big as they seem. The Tesseriaconteras (I think I spelled that right) built by Ptolemy Philopater was actually two galleys attached side-by-side with a large ram stuck on the front, so while similar in overall dimensions, it had nowhere near a similar internal capacity, and other than a short trip in harbor, never moved again for fear it would break apart.
It really seems that the problems inherent with wooden ships this large is an argument against the Ark, rather than for it.
The problem here is that the ark does not need to be a ship so much as a floating box. From a naval architectural point of view I don't see that it isn't possible, especially given the extremely vague description (outside dimensions only). One can argue that it must be either able to stay upright in a major storm or be self-righting in some manner.
But the believer can always argue that god/s helped, and in the end belief trumps logic and evidence in the fundamentalist mindset.
The design isn't as important as the strength of the material its built out of. Sure, you could build a wooden ship of the size described, but when that structure is subjected to the stresses of even moderate seas, it is going to break up because no wood is strong enough to withstand the stresses that waves place on the structure of a ship. Even if its just a big box, it is still going to be subject to sagging as a wave lifts the bow and the center rises out of the water, hogging as the wave moves to support the center and the bow and stern are unsupported, and sagging again as the wave lifts the stern but not the middle again. A wooden vessel would have to be almost solid to even have a chance to stay intact, and I'm not sure it could even then. Wooden structures that are constantly flexed back and forth don't stay intact very well, and if the stress is too great the wood simply splinters. I don't deny the proportions given are right, but you can't just scale up a 100-foot barge and say a 450-foot version would be just as good.
The (proper) design incorporates the strength characteristics of the material used and equivalent shape characteristics of the individual members.
It may surprise you to know that wood is stronger than steel on a pound for pound basis in the direction of the fibers. Wood is an exceptionally good material to work with if you know and use the characteristics involved. I have a plywood kayak that I designed and built that is stronger than fiberglass ones, stronger than aluminum canoes, and only weighs 35 lbs wet. The plywood uses the cross grain laminations to provide strength in two perpendicular directions.
Traditional construction with framing timbers with the fibers in one direction and plating planks in the other direction do this as well.
To get the same strength all you need is the same (sectional modulus) x (material modulus), where the first comes from the shape characteristics and the second comes from the material used (in the direction under consideration).
But ships experience stress in all three dimensions and almost constantly, even in calm seas. You'd need so many structural members in so many directions there wouldn't be room for anything else. What you're saying is right, but shipbuilding is a lot different than building a house.
How big are those waves?
In a global flood? With no land to block the wind and waves, swells a hundred or more feet high would be the norm, never mind a storm. I was broadsided by a ninety-footer in the Gulf of Alaska. We rolled 45 degrees and were completely underwater, and this was a 710 foot container ship. The constant back-and-forth motion takes a toll on the structure. How long do you think your kayak would last if it was constantly flexed back and forth, up and down before something gave way? Would it last a year?
As you note, the worst stress condition is either (a) where the ends are supported by waves and the middle is in a trough or (b) where the middle is supported by a single wave and the ends project from the waves.
And this will not be along the grain of the keel, which a ship derives the majority of its longitudinal strength from. Sure, you could laminate it, but its still going to be constantly flexing back and forth. Eventually, it will give.
A free floating vessel (with no power and no means to turn the vessel) will turn broadside to the waves (because of the way the water moves in waves), normally causing the vessels to broach or roll over if they are not stable in that condition (hence the need for self-righting previously mentioned), and thus will not see those critical stress conditions.
So it's constantly rolling over and over? I don't think this is much of a solution. You're just lowering one stress and replacing it with another.
You provide the stress and strain conditions to be met and an engineer could design a vessel made out of glued paper to meet them.
I doubt glued paper would last in sea water for a year. It would probably work better than wood, though, because it is more flexible.
Then there is the effect of scale on the equations: the bending stress goes up with the square of the length of a member, the section modulus (geometry strength) of a beam goes up with the power 4 of the scale used. Double the length and the stress goes up 4 time, but double the dimensions of the beam and the strength goes up 16 times, so you can scale by the square root of 2 to match strength to stress (1.414 or 42% increase in size).
The only issue here is that the structure takes up volume inside the vessel, making the available space for animals smaller. Going from 100 ft to 450 ft is a length scale of 4.5 so this creates a stress scale of 4.5^2 = 20.25 and this means a member scale of 20.25^(1/4) = 2.12. I hardly see this as filling the interior with structure.
Ballast in the bilges would further deplete interior volume available and a sea anchor could also be deployed to control the position of the vessel relative to the waves, but this would be adding ad hoc design components that are not mentioned.
This takes us back to the question of what is the passenger list of people and animals and what are the accommodations necessary to carry them, as that is a much larger impact than the structure of the vessel.
Where are you going to get 450 foot long logs to use as structural members? In reality, you are going to have joints, and those joints are going to be flexing back and forth, all the time.
You make some good points, but history shows that wooden vessels this size just don't work in practice.
Curiously, I am talking about naval architecture and marine engineering design, not houses. You may want to look around at some information available. One site (note mine btw) I found is:
Have you ever taken any classes in these subjects? Even if wood is as strong as steel along the grain, the stresses involved aren't.
Now, I don't necessarily agree with all his conclusions, but I don't think you can argue that it cannot be done, especially if you have not gone through the design process yourself.
I have gone through the design processes, and it doesn't work the way you say it does.
More critical than wave height is wavelength, as that is what determines the hogging and sagging stress loads: these are greatest when the wavelength matches the vessel length, and when the wavelength exceeds the vessel length the stresses are actually reduced from those peak loads.
Reduced does not mean negligible.
As long as the waves don't break, this can result in seaworthy behavior in small vessels subject to large waves. Sailboats in the roaring 40's for example. Also:
quote:When the wave builds and reaches a steepness greater than a ratio of 1:7, the wave breaks and spills forward. The wave has actually become too steep to support itself and gravity takes over.
So the wavelength of non-breaking (swells) 100+ft high waves would be over 700 ft and could easily exceed the length of the ark by a considerable amount, depending on the energy (height related) of the wave.
But they would still be lifting the bow and subjecting the ship to stress.
Think about Tsunami waves in the open ocean -- they cause very little disturbance to vessels at sea. Without a shore for the waves to run up on, there is no cause for the wave to build to a high peak or breaking wave, unless there is a LOT of wind.
Swells are different than waves. You're talking about apples and oranges. Swells are surface disturbances caused by wind and other things hundreds or thousands of miles away. In a global flood, those swells would have nothing to disperse them and could build on each other, regardless of the local wind conditions. They are nothing like tsunamis.
What storm? What specifically does the bible say about the weather conditions other than rain? What does it say about wind?
As has been said before, if you invoke magic than anything is possible, but if there actually was a global flood then the weather would be drastically affected. Lots of moisture in the air, lots of heat being retained by the water, big storms.
That would be my point about the ride being uncomfortable, but again this could well be a wave with more energy (height related) than ones in the purported flood.
In reality it would be a small one compared to the purported flood.
I also note that a normal container ship does not have the beam to length ratio of the purported ark -- it is made to fit the panama canal after all -- and this makes it more prone to rolling from a broaching sea.
Actually, it was worse than that. It was built in Wisconsin and had to be narrow enough to get through the St Lawrence Seaway. 710' long with a 78' beam. It was a big canoe. I always thought that was a poor choice for a ship intended for the Alaska run.
Again, a sea anchor could prevent this broadside condition, but that is ad hoc (not mentioned in the bible), but this is also how small vessels generally ride out storms with waves larger than the vessels.
Sure, but this increases the hogging and sagging stress. So you either have these stresses, or your doing barrel rolls. Neither option is particularly good.
Given that it has lasted ~30 years with a lot of that tied to a cartop traveling at 60+ mph I do not see that being a problem. If anything it is stiffer than necessary and thus I could reduce the structure next time.
Not a valid comparison. It hasn't been in water for 30 years. I'm willing to be it hasn't spent a single year in the water in those 30 years. Riding on top of a car isn't quite the same thing either. And a kayak is a lot different that a 450' vessel. You can't just scale the equations indefinitely.
How long would the ark need to last? The rain purportedly only lasted 40 days.
But they were in it for a year.
Laminated paper would be stiffer. Think of fiberglass made with chopped strand -- random fibers in a matrix of plastic.
Still don't see it lasting a year.
The believers will just say that trees grew that big. The other solution is to build up the beams with scarfed and sistered joints, a common practice to solve this very problem.
The believers can say anything they want. I'm looking at reality. And joints are not as strong as the beam itself, primarily because of the flexing that takes place. Eventually, there will be a failure.
The reasons they don't work though are not due to size. Wooden sailing vessels reached their apparent limit with the 4 masted clippers, but the stresses were cause by the rigging.
Source for this?
Then why did the Tesseriaconteras stay docked for its entire service life? It wasn't even a single hull, but it was too big to remain intact in anything but dead calm waters.
Good. Me too. Funny how what I took from them is so different from you.
This doesn't mean anything. Stresses are based on load and geometry, not the strength of the material. You can design to use the material strength to handle the stresses, whatever the material is. See reply to Theodoric (Message 210): wood along the grain is stronger than steel for the same weight.
I meant the stresses wouldn't be along the grain, which seems to render your whole argument moot. The keel, for example, would have the grain running lengthwise (X-axis), while the stresses would primarily be up and down (z-axis).
Curiously, I quoted a Naval Architect with 40 years experience that says you are wrong - that is the purpose of the link I provided. Just claiming it is wrong is not you demonstrating that it is wrong.
But your argument is only valid along the grain, which does not always hold.
Agreed, but what it does mean is that you can define the worst case based on the vessel geometry, and then design to it.
And that stress would still be less than the worst case design condition.
But still affecting it, over and over and over...
The shape of a wave is similar independent of cause, as it is governed by the physical constraints of water and gravity. A longer wavelength is more like flat water than a shorter wavelength for a vessel that has a shorter length than the wavelength. The purpose of mentioning the Tsunami wave is that a very long wavelength does not necessarily result in a high wave. What I said was
quote: ... there is no cause for the wave to build to a high peak or breaking wave, unless there is a LOT of wind.
You need to show reference to a LOT of wind in the narrative before you can assume it is there.
Why? I'm assuming nothing more than the conditions that would be reasonably experienced in a real-world situation Do you have some reason to think that there would mysteriously be no wind anywhere in the world during the flood? I think you need to support your assertion that there was no wind more than I need to support the assumption that there would be some and it would cause swells just like it does today.
Like the roaring 40's, which changes dramatically depending on weather conditions. Some days can be quite calm.
In a steady state condition the swells would increase in wavelength in an open world wide sea.
And would also increase in amplitude with no land mass to stop them. Waves (and swells) can build on each other as the frequencies match up.
But I'm NOT invoking magic, I am pointing out that you are making up stuff that isn't necessarily in the narrative.
You are making things up if you assert that somehow there was no wind. The bible doesn't mention that either.
Without any credible information on the actual weather and sea conditions from the narrative, you would have to show a vessel cannot survive in the best conditions that meet the narrative information, otherwise you are creating potentially false conditions.
No, what I'm doing is projecting the probable weather conditions that would be experienced in the conditions described by the narrative. I see no reason to assume that there was no wind anywhere on earth during the flood.
(A) how do you know this?
Because I've studied the effects that land has on weather and sea conditions, and what the lack of land would do to them. It wouldn't be millpond conditions all around the world, that's for sure.
(B) a larger wave, once the length of the vessel is exceeded, makes less of a problem, as the water surface relative to the vessel become flatter.
That doesn't make the stress problem go away, it just means it won't be as bad as it could be. A vessel riding up and down 100 foot swells, even with a thousand or fifteen hundred feet between them is still subject to hogging and sagging.
Yeah, but shipping companies make lots of poor choices with other peoples lives.
Well, the food was good anyway.
So you are comparing the stability of a vessel with a larger length/beam ratio and likely a higher depth to beam ratio and possibly a higher CG to the purported ark in order to say that the ark would be unstable?
No, I've never said the ark would be unstable. I said it would break up in rough seas.
How so? A sea anchor would be a load in a different direction.
A sea anchor would keep the bow into the wind and waves, thus causing greater hogging and sagging stress than if it was lying broadside to the waves, when it would be rolling back and forth.
Why barrel rolls if the swells are a long wavelength exceeding the length of the vessel? Large but long drawn-out swells are not necessarily a stability problem.
You're assuming it would only experience long swells. I'm not.
Again you need to show reference to a LOT of wind in the narrative before you can assume it is there.
Wind exists in the real world. Why would it not exist during the flood?
You asked for it.
No, I asked how your kayak would react to being constantly flexed at the bow and stern, over and over for a year. You changed the comparison to being strapped to the top of your car. That's what I said wasn't a valid comparison.
Correct, the stresses on a rooftop are likely considerably higher than sitting in the water for a year.
But sitting in water while being flexed back and forth...?
Sorry, but that is how actual design is done, by the equations, based on the calculated stresses and the material strengths.
But not by assuming that your can just add material to make it stronger by the same amount. After a certain point, the weight of the material limits how much extra stress it can take. And your calculations are still dependent on the strength along the grain of the wood.
Vessels larger than the purported ark have been designed - you rode in one - so we are not talking about extrapolating off the end of known data.
No, but we are talking about scaling up from small wooden vessels to larger ones. You are assuming that increasing the size of the beam increases its strength by the same amount, regardless of the size. From what I remember, that isn't automatically the case.
And what were the weather wind and sea conditions?
I'm willing to be they weren't millpond calm.
Curiously, your opinion is not able to affect reality.
No, but I'm basing my opinion on that reality.
Are you? Without contradictory information you would need to assume the best case conditions from the information provided in the narrative.
Why not assume normal conditions based on what we know about weather? That's all I'm doing.
We can look at trees that are known to exist and see if they are long enough and large enough to provide material needed to build a vessel to the parameters given in the narrative. From what I can see, they exist such that a vessel could be constructed with wooden boat building technology.
Sorry, I wasn't very clear. You keep talking about the strength of wood along the grain, so I was referring to finding a tree of sufficient size to carve a keel beam 450' long so that the grain would actually be in the same direction as the hogging and sagging stress.
Again, this is a design issue. The joints are not as neat as in a steel vessel, where material can be welded, but even in a steel vessel the joints are made with brackets to increase the strength and the joints compared to the middle of the beam.
This is why traditional wooden vessels used knees.
None of which you can do with a wooden vessel. So you still have joints, flexing back and forth. Knees aren't as strong as welds.
Google 4 masted clippers, and you will find videos of one of these vessels in a storm with the bow snaking around in response to loads from the rigging.
Not arguing that the rigging caused stress. I'm disputing that the rigging was the main source of stress.
The loads on that vessel would be due to the oars when it was taken out. Sitting there it did not have those loads.
The oars caused too great a load on the ship? Seriously? I'd really like to see a source on that.
My argument that wood is lighter than steel only applies along the grain. Now you are talking about sheer loads within the members, and this is a function of area vs stress.
That's what I've been talking about from the start.
Again, you define the stress conditions, and then we can design to meet them.
Why? So you can dispute them and claim that without a specific description in the bible, we can't assume anything more than millpond conditions? I have reality, in which no wooden vessel larger than 400' has had any success whatsoever, and even then only limited.
How much and for how long? Define the stress and you can design to meet it.
The bible says they were in it for a year, but you don't seem to think there were any waves.
After the 40 days of rain don't we have a different survival condition, one that even a wounded ship could survive?
Not in reality. There would still be wind, swells and storms, unless you have some reason to think there wouldn't be?
How do you know they are reasonable if you don't have any information about the actual conditions? Assumption?
Experience. I have sailed on the ocean, and I know the conditions one experiences there.
I didn't say there was no wind, I said that there was no real information on the wind, and that without information you are making stuff up to imply your case is stronger.
I'm not assuming constant gales. I'm simply assuming similar conditions to what is experienced today, with the removal of the canceling effect of the continents. Why is that not reasonable?
I've seen heavy rain with no wind, so it is possible.
quote:7:12 And the rain was upon the earth forty days and forty nights. 7:17 And the flood was forty days upon the earth; and the waters increased, and bare up the ark, and it was lift up above the earth. 7:18 And the waters prevailed, and were increased greatly upon the earth; and the ark went upon the face of the waters. 7:19 And the waters prevailed exceedingly upon the earth; and all the high hills, that were under the whole heaven, were covered. 7:24 And the waters prevailed upon the earth an hundred and fifty days. 8:1 And God remembered Noah, and every living thing, and all the cattle that was with him in the ark: and God made a wind to pass over the earth, and the waters asswaged; 8:2 The fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained; 8:3 And the waters returned from off the earth continually: and after the end of the hundred and fifty days the waters were abated. 8:4 And the ark rested in the seventh month, on the seventeenth day of the month, upon the mountains of Ararat.
Rising water. Some wind, but how strong not mentioned. No storm conditions mentioned other than rain.
So you are advocating that god was magically interfering with the weather, preventing the normal conditions from being experienced. When you invoke magic, you can explain anything.
Yes, and the loading would be significantly less with longer swells. The period of swells is related to the fetch of the wind (even little wind) so the swells could be very long but not very high.
Not if they are building up over thousands of miles, with no continents to interfere.
And without any information to derive a reasonable sea condition there is no rational to assume one with sever loading conditions.
Just experience and reality, but you don't seem to be interested in those.
By the way, I'd still like to see some support for your assertion that the oars on the Tesseriaconteras were the source of its structural problems.