About that Boat - Noah's Ark

The comparison of the Ark to modern (or rather 19th century) wooden ships has problems. When it comes to ship design and strength, a boxy barge is the strongest design. The weakest design is the streamline shape, especially when constructed of wood. However, sailing vessels need to be streamlined so thier stength compared to a barge shaped Ark will not be applicableHogging: Hogging is a problem primarly for streamlined ships -- steel or wood. Barges ususally do not have that problem. For wood ships the problem is increased when the primary structural members are pieced end to end the length of the ship as the typical 19th century sailing vessel was. The best way to reduce the effect of hogging is for the top and bottom structural members to be full length (from 'bow' to 'stern') of the vessel.Draft: It is thought that the draft of the Ark was 15 cubits (1/2 height). With this draft and barge shape the vessel would be very stable. The height of the wave in comparison with the height of a wave is only half the story. The heigher the wave, the longer the wave length. The wave that will cause the worst problem is the wave that has the a wavelength the same length as the ship because the ship will experience the worst sagging or hogging. Even large crosswise waves would not be the problem often imagined.

We should actually be comparing it to ships built 5000 years ago, .... Comparing the ark to recent wooden vessels is actually giving the tall tale a lot of leeway.... The largest known such ships were built in Ming China in the 14oo's for the explorer Zheng Ho.****Comparison between ship designs should be made between similar styles regardless of era -- i.e. apples with apples, oranges with oranges, etc. It is usually the critics of Noah's Ark, et. al., who do the comparisons between 19th century sailing ships and Noah's Ark. In this post, I was simply pointing out that a comparison between a barge and a streamlined vessel has problems.>>When it comes to ship design and strength, a boxy barge is the strongest design.Prove it. I can think of no reason this would the case.****This is very easy for you to check out. Simply do a search on the internet for Naval Architects (or Naval Architect Companies) then email them the questions about which shape is stronger when built out of the same material. (I can save you a lot of time: The barge is much stronger.)>>Hogging: Hogging is a problem primarly for streamlined ships -- steel or wood.This makes no sense. If you support a structure in the center and leave the ends dangling there is going to be stress on the frame, especially when talking about a structure as large as the ark.****All ships and barges hog and sag -- flexing as they travel through the water and waves. However, hogging, is a permanent change in the shape of the ship over a long period of time. ALL wooden streamlined vessels will eventually ended up hogged (if they didnt sink first) Many early steel ships also hogged. Now days the ships are over designed to reduce the effect of hogging on a streamlined ship.Hogging happens over time because the streamlined shape of the vessel provides greater boyant support in the middle of the ship because that is where it is deepest and widest. There is very little boyant support at the bow and stearn because of the need to streamline the ship. So, the ends of the ship hang down from the middle of the ship.On the other hand, barges have the same boyant support from stem to stern. So, they won't end up hogging.>>Barges ususally do not have that problem.Perhaps because barges are not typically run in the open ocean under storm conditions worse than we can imagine?****Again, a simple search on the internet will find that there are several ocean going barges and companies that construct them. Go ask them a few questions.>>>...The best way to reduce the effect of hogging is for the top and bottom structural members to be full length (from 'bow' to 'stern') of the vessel.umm... right. The ark was 450 feet or so. The tallest tree now living is 367.5 feet. It is short by nearly a 100 feet, and is in California, not mesopotamia. ... Were is the evidence that such lumber even existed for Noah to use?****To be sure, no one knows precisly what was the ecology of a preflood world, however, There is interesting evidence in the gologic record that many plants and animals were larger than they are now. While one cannot point to any specific tree fossil being large enough to do the job, the general trend in largeness supports the idea that there could have been trees large enough....With a length to width ratio like that, it would snap like a twig in storm waves. Milling would further reduce the tree and thus weaken it.****Lets see some facts and figures that would show that a box-girder designed barge shaped vessel constructed of hundreds of such pieces would "snap like a twig." Design calculations that I've done indicate that given the proper crossectional area of stress bearing members, a wooden ship the size of the Ark could handle most stresses it may encounder.>>Draft: It is thought that the draft of the Ark was 15 cubits (1/2 height). With this draft and barge shape the vessel would be very stable.So you consider rolling round and round like a pencil to be stable? Everything inside would be beaten to a pulp.****I just said that the barge design at the ratios of 300x30x45 at that draft would be very stable. Experiments have shown that a barge like this would be quite stable. It would right itself, even if tipped to near 90 degress. Certainly, not like a pencil, or some round-bottomed boat.>>The wave that will cause the worst problem is the wave that has the a wavelength the same length as the ship because the ship will experience the worst sagging or hogging. Even large crosswise waves would not be the problem often imagined.What is the point?****I figured you were smart enough to see it for yourself. The larger the wave (the higher it is), the longer the wavelength. Large waves who's wavelength is longer that the length of the vessel will causes less stress on the ship than those waves who's wavelength is the same length as the ship. Ships that are designed for waves who's wavelength is the same as the ship will be designed for the worse case. All ships are designed for this case.So, even if one proposes that there were waves during the flood cataclysm that were much larger and longer than the Ark, it is the waves which have a wavelength the same length as the ship which would cause the most stress on the vessel. Big waves are not a problem so long as the Ark was designed to handle waves of the same length as the ship.

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So, Noah and his sons were naval architects.

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Thats not what I said. According to the Biblical record, God told Noah how to build the Ark. Presumably, God designed it and described to Noah how to build it. On the other hand, Noah may have hired ship designers to design it according to the general description provided by God.

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They knew from experience between goat and sheep herding and farming

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It is your assumption that Noah was a herdsman. There is no such indication in the Bible.

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Not only is there a problem of comparing 19th century wooden vessels with those built 5000 years ago, there is a HUGE problem with applying 21st century logic and thinking to people who lived 5000 years ago.

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A discussion of the strengh of any ship from any era according to modern knowledge is entirely appropo. But, we cannot assume that they knew what we know. On the other hand we cannot assume that they did NOT know what we know. And if the Ark was designed by God and built by Noah according to a design given him, then the knowledge of shipbuilding in that day may be irrelevent.

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I would venture to guess that you have never been on the open ocean in a storm.

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1961, Indian Ocean, aboard the 250' HMS Warrick Castle, on the edge of a typhoon. The ship was smashing through waves as high as the main deck (30-40') with the wavelength about .75 times the length of the ship. Screws were often beating in the air. I was 10, having a great time trying to walk the halls and not smash into the walls and running across stairways as they went flat! Most of the water splashed out of the swiming pool so we couldn't go swiming. Allen

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Where do you get this stuff?

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(In a hogging condition, the deck of the vessel is placed in tension, and the bottom structure in compression.)
Ship Structure Committee: Case Study I: NEW CARISSA

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It isn't about long term deformation, but about flexing.

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Davis, Andy, 1993, "Understanding the longitudinal deformation of wooden ships: HOG," Wooden Boat, July-August. pp 70-81.In the above mentioned article the author discusses the problem of permanent hogging deformation. Hogging can refer both to the typical flexing that ships encounter and to a permanent deformed condition. AKA "Hogged"

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So your point is about the distribution of bouyancy? It doesn't make any difference. Riding the waves will make the barge hog.

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Yes, all large vessels hog and sag in waves, but we are getting away from the point. That point is that a streamlined ship is inherantly weaker for the same size and same construction material than a barge shaped vessel. One example of that is the fact that streamlined ships experience a permanent stillwater hogging that a barge shape does not.

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A ship the size of the ark will undulate in the waves and crack apart.

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Yes, the ark would hog and sag, however, the proper design can keep even a wooden ship from cracking apart.

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A barge may in fact be worse, since as the bow dives into the water its inherent bouyancy will drive it back up with greater force that than would the reduced bow of a streamlined ship.

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The advantage of a streamlined design over a boxy barge is in moving through the water. The Ark was not designed to move efficiently through the water, but simply to stay afloat. The strength of the barge shape makes up for any differences in stress encounted with waves hitting the vessel.

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I notice they are all steel, and most are under 400 feet. I thought we were talking about timber? You aren't going to compare steel barges with wood are you?

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The comparisons I was making was between vessels of the same size and same construction material. However, one can extrapolate from steel designs to wood designs provided you allow for differences in the strength of materials. For instance, the main stressing bearing members on a steel ship about the size of Noah's Ark are the main deck and bottom planking (sic). Typically these are designed at 2 to 2.5 inches thick of steel to withstand the expected stresses of approximatly 9 tsi (tons per square inch) for that crossection area. A wooden ship of the same size would need to have the main stress bearing members (top and bottom) to be about 21 to 25 inches thick. This would spread the stress out over a larger crossection area, reducing the stress to 1 to 1.5 tsi (which is within the compression strength of most hardwoods).

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Sure we do. It was only 5000 years ago. There is a lot of evidence. ... other than that Mesapotamia had a wetter climate.

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This shows up the differences in paradigms between you and I. For me, 5000 years ago was pre-Flood and that all 'ancient' cultures that have been dated earlier than the Global flood some 4000 years ago are dated in error. (yes, I am familiar with all the "evidence" for these 'ancient' cultures, but reject it as interpretation.) Thus, all these "ancient" cultures have no relationship to the pre-flood world.

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There was no "general trend in largeness."

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The 'general trend in largeness' that I was talking about is found in the fossil record, which I believe was buried in a global cataclysm and not the result of millions of years based on gradualistic interpretation. (yes, I'm familiar with all the "evidence" for millions of years of evolution, but reject it as interpretation.)

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The first references I can find to box-girder design refers to construction in the 18oo's. And, in fact, some of the first attempts failed. The engineering experience just wasn't there. So we are to assume that Noah had such knowledge 5000 years previously?

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As mentioned before, Noah need not have had the experience if he was building according to God's design. The idea that the Ark was a box-girder design is based on the idea that the Ark was a barge built to the ratio of 300x50x30

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It seems to me that if you put hundreds of ten foot diameter beams in a boat 75 feet wide and 45 feet tall, you would have not much room for anything else.

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A vessel of wood with the top deck/roof planking and the bottom planking 21" thick would be able to withstand the typical design stress required for modern steel ship design.

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Your ark is smaller than typically proposed. 450' long by 75' wide by 45' tall is more typical.

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I meant to say 300x50x30. This is the size mentioned in cubits. If an 18" cubit is used then you get 450x75x45. If a 21" cubit is used then you get 525x87.5x52.5

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If tipped up on its edge, a box is equally likely to fall onto its top as its bottom.

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The center of mass of a barge that has a draft 1/2 its height will be such that even when tipped abeam up to 90 degress it will be pulled back to the upright position. This assumes that all cargo stays in place (i.e. all animals remain in cages and all food and water remains in their containers).

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Lets see those designs and calculations.

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Lets supposed that the major stress bearing members of a barge shaped vessel were the top deck, keel deck and the two sides. For simplicity lets make them all 1 cubit thick constructed of wood. (for simplicity we well ignore transverse members, any other longitudinal members and decks) We will compute this as a box girder supported on two ends.The Moment of Inertia of the crossection for the upper and lower members is
I = Ah^2(upper) + Ah^2(lower) + Ak^2(upper) + Ak^2(lower) - (A(upper) - A(lower)) = 21033.34 cubits^4.
Where area A=50, h^2=14.5^2, k^2=n^2/12=1^2/12. (k=radius of gyration)The Moment of Inertia for the two sides is
I = 2(bh^3/12) = 3658.7 cubits^4
Where b=1, h=28.The total Moment of Inertia is 24692 cu^4The Section Modulous is
SM = I/y = 24692/15 = 1646.13 cu^3
Where y = draftDisplacement = W = 15*300*50*D = 225000D lbs
Where D is density of water.Bending Moment = M = WL/8 = 225000D*300/8 = 8437500D cu-lbs
Where L is length of box girder/vessel.Stress = s = M/SM = 8437500D/1646.13 = 5125.7D lbs/cu^2For a 21" cubit and a water density of 0.03606 lb/cu^3 we can find the stress in psi as
5125.7*(0.03606)*21 = 3882 psiThis is the stress for a box-girder vessel supported on each end. However, the stress for a vessel supported full length in water is less.The design stress for the cruse ship Savannah (545x78x30 ft) floating in water is 7.67 tsi. However, if the Savanna were to be put in dry dock and supported just on two blocks 545 feet apart, the calculated stress would be about 30 tsi. Thus the design stress is approximatly 1/4 the calculated stress as a beam supported on each end.So if we go back to the calculation above for a wooden vessel the size of the Ark the stress would be 1/4 of 3882 psi which is 970 psi.But what is the crush stress for some hardwoods?White Ash 7410 psi
Yellow Birch 8170
Sugar Maple 7830
Black Locust 10180
Live Oak 8900Soft woods
Douglas Fir 6360 psi
Western Hemlock 7200
Tamarack 7160So, the computed design stress of about 970 psi is well within the crush stress of many hard and soft woods. Such a designed vessel is capable of passing the requriments needed for modern ship design.

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Having some experience in both vessel design and construction, I've decided to try a little experiment. Using MacNaughton's Scantlings Rules for Wooden vessel construction, I'm gonna calculate the scantlings for a 450' wooden vessel.

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I am really interested in what your results would be. I'm not acquainted with MacNaughton's Scantlings Rules. Are they the rules used for building 19th century sailing vessels? From what I've read one of the major problems with the rules of 19th century ship design was that there was absolutly no knowledge and testing of the strength of materials. Very few, if any, ever measured the stresses that ships encountered. To build a bigger ship one mearly scaled up from emperically based ship designs that had a better success rate than others. What most did not realize is that after a certain point in scaling up, a streeamlined, keel based ship design becomes so weak and flexible that nothing, not even steel bands, can keep it together.All the modern methods of computation and measurement of stress in shipdesign came about with the invention of steel ships, especially during WWII when many of the steel Liberty ships broke apart and sank for no apparent reason. Out of the need to have trustworthy ships for the war effort came modern ship design with special emphasis on strength of materials and stress computations.For these reasons, the design I calculated above is a keeless, box-girder barge design roughly similar to supertankers.

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# of animals/kinds (WTH is a kind anyway?)
Amount /weight of food

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The draft of the Ark is thought to be 15 cubits (i.e. 1/2 the height). With that knowledge you can figure the displacement without need to answer the questions you pose.

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A wooden boat that size, with no way to control it during a tempest that would make the Perfect Storm seem like a summer Sunday sail

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Experiments with a model in a wave tank (done in the 1980s) show that with a 300x50 length/breadth ratio the vessel automatically turns normal to the waves. But still, no one said that a 110 day ride in the Ark was a walk in the park.[This message has been edited by allenroyboy, 08-29-2003]

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and don't forget the really big door in the side-- Genesis 6:16.

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Obviously, you know next to nothing about ship design. The one place that experiences the least amount of tension and compression stresses, the one place that experiences the least amount of shear stress is located on the side of a vessel midway between top and bottom and midway between bow and stern. Check it out. Take look a most any modern ship (especially cruise ships) and you will see that they have doors in the sides in the middle of the ship.

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How much time Noah and his sons had for felling/milling the wood and constructing G-D's yacht?

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Most Bible scholars will tell you that Noah was given about 120 years to build the Ark. Besides his sons, Noah may well have hired other workers or extended family members to help in the felling, shaping of the wood and the construction of the Ark.If you do a little research on the internet you will find that others have already done some of the research and calculations you are proposing.

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Why would you concern yourself with a permanent deformation? The boat was allegedly only afloat for a year, tops. This is an irrelevant issue.

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The only reason for mentioning the permanent deformation was to illustrate the fact that streamlined design is inherantly weaker that a boxy barge design. That's it. Thus, a comparison between streamline designed vessels and barge design vessels is limited.

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That is what we are talking about. No one today can make it happen. ... The issue, in fact, is whether ANY design at all would work considering the materials.

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Correct! I believe that a barge shaped (box-girder) design is capable of handling the tension and compression stresses in the top and bottom stress bearing structural members.

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where are the modern 400 foot ocean going barges?

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There has probably not been any need or demand for any that size.

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The designs of steel and wooden ships are radically different, due to the differing properties of the materials. It is not that simple (to extrapolate).

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Correct again. However, when it comes to the computation of stresses on the main stress bearing structural members, the methdology is comparable.

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it doesn't take much though to realize that the steel sides of a ship are going to be its lengthwise strength. You seem to applying chord-truss dynamics to something that isn't a chord-truss.

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According to the Naval Architect books and articles I've read, the steel sides of any vessel carry very little of the primary tension/compression stresses. It is the main deck and bottom planking (sic) that carries the bulk of those stresses. The formula I used above comes from a Naval Architect book. In the calculations above you will see that the two sides together carry less than 18% of the total compress/tension stresses.

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You cannot simply scale up the material. It doesn't work that way. If it did, we could built wooden ships of any size whatever, as long as we used enough wood.

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As long as differences in construction methods are adhered to, it is possible to scale up from steel to wood. It may not be simple, but it can be done. It is true, that finding enough wood today would be a definite problem. Much of the old growth timber world wide is gone.

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You are forgetting about torsion, shear, elasticity, bending, and various shock loads. Wood is typically high is compression strength, but compression is the least of your problems. Most of the stress will be of one of the other varieties, especially torsion.

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No, not forgetting, just starting with first things first. The largest forces a ship experiences are the compression and tension stresses in the main deck and bottom planking. Once you design to meet those needs you move on to the lesser stresses. All are important and must be taken into account and designed for. None of the other stresses, including torsion, are of the magnitude, alone or together, of the compression/tension stresses.

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A 400 foot long piece of wood 21 inches thick and supported at either end couldn't even support itself. Rolling over storm swells would simulate this condition as well as the reverse-- supported at the center-- over and over.

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Was I really that unclear in my description or are you being intentionally obtuse?
In my calculations I only dealt with the following stress bearing structural members, the top deck, the bottom (or Keel) planking, and the two side planking. I did not discuss the needed framework of the vessel to held these members in place, because I thought that you would understand that such a framework would be needed and in place. That framework would also add to the structural strength of the vessel, but I just wanted to simplify the problem and only deal with the four major members.
I also assumed that each of the stress bearing members, though composed of many individual planks 1 cubit thick, perhaps about 1.5 cubits wide and some 450 feet long, was a single member 1 cubit thick and 50 cubits wide (e.g. for the top deck). This is not a bad assumption since all the pieces would be fastened to the frame and to each other to act as a unit. Obviously, one would want to do a much more detailed computation involving each member to get more accurate calculations. What I did above was to get a rough estimate.

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The ship will twist and flex as it rides the storm swells. This twisting will cause the timbers to move relative to one another and break whatever water seal it initially had. This was a huge problem in much smaller wooden ships of the 17oo's and 18oo's.

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Yes indeed. This is especially a problem for streamlined vessels where the planking is bent and warped to fit the streamline shape. As I said before, streamlined, keel-based ships are inherently weaker than a barge shape where internal cross-bracing can easily reduce torsion stresses. No doubt there was movment between timbers that allowed for leaking in the Ark. But it is possible to design a barge shape vessel that can keep leaking to a minimum. Then too, the ship was likely afloat for only 110 days.

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Engineers have often attempted to analyze the structures of wooden ships as if they were homogeneous box girders. This is a common misapplication of beam theory. Actually, a wooden ship, especially as it ages, more closely resembles a rather weakly bound bundle of reeds. These reeds are free to slide past each other. If traditionally built wooden ships were box girders, then one would expect to see many tensile failures amidships in the upper deck of a severely hogged vessel; however, this is not the case. Failures in longitudinal structure are infrequent and tend to be scattered almost uniformly throughout the vessel. The idea of "strength decks" or "extreme fiber" is largely irrelevant to the meaningful analysis of old wooden ships. Microscopic investigation reveal a generally low level of stress in "hogged" structural members. There often is evidence of plastic behavior, creep, around fastenings. Large overall deflections in the hull can be achieved with a very small amount of creep around the fastenings.
http://www.tricoastal.com/woodship.html

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What a fantastic quote! It proves what I've been trying to say all this time! It shows that you cannot apply modern, typical, homogenous box-girder design to wooden sailing vessel design of at least the 19th century. The reason why is that the old wooden ship design was Keel/rib based. All (or most) of the stresses were supposed to be handled by the keel. The rest of the vessel, Like the man says, was "a rather weakly bound bundle of reeds." The design methods are so different that you cannot use the modern box-girder method to analyze the old keel/rib method. And the converse is true, you cannot apply the failures of the keel/rib method of design to a wooden vessel designed according to the modern box-girder method.What I've been doing is to design a wooden vessel according to the modern, keeless, box-girder design method. In the box-girder design the frame and the planking share in the stresses (unlike the keel/rib design. As he said, there was "a generally low level of stress" in the hogged members.). The computations I did above were based on the box-girder design. Therefore, just as the man says above, what I've been doing cannot be compared to the wooden sailing ships.In this design the "reeds" cannot be free to slide past each other. Not only do they need to be securely fastened to the frame, but they also need be securely fastened to each other (which was not done in the old ships). By fastening the members to each other, they become, in some respects, a larger whole. Thus, in my rough estimate computations, I treated the top deck as a single unit crossection of 1 by 50 cubits. One would want to refine the calculations by considering each plank individually and how it is fastened to the other structural members. Any volunteers?As he says above, the permanent hogging happened because of creep around fasteners. This allowed the ends to droop in respect to center due to the streamlined design of the ships. Creep around fasteners on barges would not result in permanent hogging, rather it would allow the barge to flex more readily than at first, which would not be good thing either.

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There has probably not been any need or demand for any that size.

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So that bit of evidence hits the bottom.

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Not at all. It is demand and economics that determines the size of any ship built. Just because ocean going barges are not built as large as the Ark, that does not mean that they could not be built that big. Just consider supertankers. These ships are nothing more that huge, box-girder barges with just enough rounding at the bow and stern to make it economical to push them through the water. They are not streamlined ships.

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Look. Build yourself a long thin box out of any material you have. Support each end, then remove the sides. The center sags. You can support the middle only, and get the same results. Now put the sides back and remove the top and bottom. Surprise! Not nearly as much sag as when the sides are removed. If you have ever built anything at all, you should know this.

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In my computations above I included the sides which are needed for the very reasons you mentioned. And more than that, I computed the amount of compression/tension stresses these necessary members carry == approximatly 9% of the total compression/tension stresses each.OK, lets compute the shear stress (Fv) for the sides for the design I have been working with.
First you find the shear (V) V = w (l/2 - d)
Where V is shear in lbs. w is in lbs per liner foot of the crossection of the box-girder. l is the length of the vessel. d is the depth of the beam. Also, w is equal to the density (D) of the structural material times the crossection area (A) w = DASo we get: V = DA (300 / 2 - 30) = 120DAShear stress is Fv = 1.5 V / A lbs / square cubit.
By substitution we get Fv = 1.5 (120DA) / A
This reduces to Fv = 180 D lbs/cu^2I have here a list of specific gravity (G) and "maximum shear stress parallal to grain" for several types of wood.First we'll compute the psi for a specific gravity of 1 with a cubit of 21 inches then convert that to the specific gravity of the woods and compare the computed shear stress (Fv) with the maxim shear stress parallel to grain.Fv = 180 * .03606 * 21^3 / 441 = 136.3 psiHard Woods---G------Fv------Max shear stress
White Ash___.60___ 81.78 psi__ 1910 psi
Rock Elm ___.63___ 85.87 _____ 1920
Live Oak ___.88__ 119.94 _____ 2660Soft Woods
Douglas Fir .46___ 62.70 _____ 1000
Western
___Hemlock -.45___ 61.34 _____ 1290
Tamarack ___.53___ 72.24 _____ 1280So as you can see, the computed Shear Stress (Fv) is far below the maxim shear stress parallel to grain of most any wood. Your concerns about shear stress are not very well founded.

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The bundle of reeds metaphor implies that the ship is comparatively poor at resisting longitudinal loads due to a weakness in shear.

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How true! The shear stress was too great for the sides because the keel was unable to handle the compression/tension stresses and passed on the bending to the side planks. They broke because they were not designed to handle shear stress and the ship sank. The whole problem is the keel/rib design.The problem with the Keel/rib design is that the keel is simply not tall enough to handle the stresses properly. This is easily illustrated by using a 2 by 4 piece of lumber. Lay it flat between two saw horses, get your kids to walk across, and it will bend quite easily. Set it on edge, and it will hardly bend at all. Why? simply because when it was flat the top and bottom surfaces were only about 1.75 inches apart. But when it was on edge the top and bottom surfaces were about 3.75 inches apart.The top and bottom surfaces of keels in most wooden sailing vessels likely ran only 10 to 15 feet apart. This is contrasted with the distance between top and bottom surfaces of box-girder designs where, like in my ark design, the distance between the top and bottom is some 45 feet. It is greater than that for supertankers. The greater the difference between the top and bottom surfaces of the stress bearing members the stronger the ship and the greater the stress that can be handled.

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I assumed such a framework, but no framework will give you as solid a structure as you assume. Each individual member will move relative to every other and be subjected to a reduced version of the stress described.

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The frame I have envisions would consist of longitudinal, transverse and vertical members each some 18 to 21 inches through. They would be securely fastened at the verticies and the entire substructure would be diaganally cross-braced longitudinally and transversely. It might not look pretty, but it would be strong. To be certain the members would all move some and one would want to calculate all that sometime.It is this cross-braced truss substructure that would handle torsion forces. Tortional stresses are less than shear stresses, and shear stresses are less than compression/tension stresses. I really doubt that it would be hard to over-design a box-girder vessel agains torsion stresses.

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What I did above was to get a rough estimate.

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Too rough.

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Where are your calculations to back that up.

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allanroyboy keeps using a single timber analogy for strength, seeming to forget a wooden vessel is a sum of its parts. All members, backbone, deck planking, framing, work together to give the vesswel its strength.

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I have already said that I have made some simplifying assumptions to come to some rough conclusions. You are absolutly correct that a top deck, for instance, would consist of many parts, and that you need to compute the stresses for each part, considering its fastenings and add/subtract it all up to get a better estimate. However, no one has detailed plans for a wooden vessel of that size so it would be hard to do such a detailed study. It would also take the same specialized programs used for modern ship design to do the calculation properly. Which I don't have.The calculations I did were based on the idea that all the parts of say, the top deck, were fastened together in such a way that they would tend to act as a whole unit rather than a bunch of individual pieces. Obviously you could not get such fastenings to act as if the parts were 100% of a whole, but you could get reasonably close -- possibly 80 to 90%.

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What NA sources are you using?

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Back in about 1997 John Woodmorappe and I had a rather extended email discussion with a self-proclaimed NA who claimed that a wooden Ark was impossible. That discussion triggered an extensive, if not exhaustive, literary search and study. From information supplied by the NA and what we found elsewhere, we concluded that the NA was misinformed. One thing we found is that most NAs know next to nothing about wood shipbuilding. This not a condemnation, just a simple observation. After all, how many large wooden sailing ships are in demand today? All training is aimed at building steel vessels. All computer aided design programming is aimed at building steel ships. The art of woodship building is nearly lost.The formula I have been using have come from the NA and an assortment of books and articles on shipbuilding. My minor background in Civil Engineering helped me as I studied the issues and problems. I don't claim to have all the answers and I'm willing to learn more about Naval Archetecture.

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All members, backbone, deck planking, framing, work together to give the vesswel its strength

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By backbone I believe that you are referring to a Keel. The box-girder design ive been discussing does not have a Keel or backbone. In fact, it is the Keel/rib design of woodships that limits the size of woodships. I explained elsewhere about why that is so.

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I hope to start the calcs this weekend, work permitting.

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I look forward to studing the results of your work. However, if your calculations are based on a Keel/rib design, chances are very goood that your computations will show that a size of 450' is not possible. This is to be expected when using a Keel/rib design. However, as was posted elsewhere, such Keel/rib design is not comparable with box-girder design.Allen

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How the hell do you get the draft without knowing how much weight is on the ship? This is inane. Where did you get this figure? It isn't in the Bible. Who made it up for you?

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"The waters rose and covered them mountains to a depth of 15 cubits..." (Gen 7:20) Since Noah and family were closed up in the Ark, it is highly unlikely that they were out making soundings to see how deep the water was. But, they would be able to notice if the ship were ever grounded during the voyage. Since it did not come to rest until after 150 days, then the water upon which it floated that whole time in must have been deeper than the draft. Since they likely started in a mountainous area and landed in a mountainous area, then the water over the mountians had to be deeper than the draft of the Ark. Since they mention 15 cubits as the depth of the water rather than any other number, then it is likely that 15 cubits was the draft of the Ark.

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What experiment? Who performed it? Were are the results published? How large were the waves? How was the model constructed? The devil is the details.

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In the 80's there was a movie called "The Search for Noah's Ark." In it was a segment showing a model Ark in a wave tank. A book was also published by the same title that had all the information that appeared in the film. What details I remember is that the model was about 6' long and it was encountering waves a few times higher than the vessel and that the wavelength was nearly twice the length of the model. The film clip showed the model turning normal to the waves with the passage of a few waves. To be sure this experiment did not take into consideration what ever winds there might have been.Allen

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2) As has been pointed out before, your logs will warp, crack and twist as they dry. This action will break many of the joints. If Noah starts with dry wood, then you have the problem of connecting wood that is already twisted-- huge pain, trust me. And, dry wood will re-absorb water once it gets wet. This, also, will be hell on your joints

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One would of course propose that the wood was properly cured before any forming of the members began and before the construction of the vessal began. Thus warping may not be that much of a problem.As for re-absorption of water, this is something to prepare for. "And coat it with pitch inside and out." Gen 6:14 This implies that some kind of sealant was administered to the hull both inside and out. To be sure, water would still be absorbed, but it would be limited. And all the vessel needed to do was to float for 150 days.

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Check your ship building history. The planking on Roman ships was mortised together. The clinker-built design design relied upon the strength of the shell and is found as early as aboput 2500 years ago. The planks were in fact lapped and fastened together. The caravel-built design is the keel and rib design you mean. The caravel was adopted because it allowed for longer ships. Sounds like you want to do both.

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I believe that some of the ancient egyptian boats were also mortised together. The ones I was refering to, apparently, as never doing that was the caravel. By old, i was meaning a few hundred years and not ancient -- a few thousand years. While the caravel design could mean longer ships, there is still a size limit. The Box-girder design allows for even longer and bigger ships. And why not use dowels or mortises to fasten timbers together? There is certainly no rule against it.

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It does mean that you cannot cite such barges as evidence, as you did.

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OK, hold on, for what reason did I make reference to barges. Originally I said:

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"Barges ususally do not have that problem (hogging)."

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I was comparing a barge with a streamlined vessels in reference to which one was inherently stronger than the other. You then changed the subject by stating:

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"Perhaps because barges are not typically run in the open ocean under storm conditions worse than we can imagine?"

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To which I responded that there are ocean going barges.

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"a simple search on the internet will find that there are several ocean going barges and companies that construct them."

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In response you then again changed the subject.

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"I notice they are all steel, and most are under 400 feet. I thought we were talking about timber? You aren't going to compare steel barges with wood are you?"

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I attempted to get back to the main subject of comparison between the streamlined design and the barge design:

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"The comparisons I was making was between vessels of the same size and same construction material."

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To which you then again changed the subject:

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"Then where are the modern 400 foot ocean going barges?"

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I responded in kind by noting:

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There has probably not been any need or demand for any that size. Just because ocean going barges are not built as large as the Ark, that does not mean that they could not be built that big.

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To which you now respond:

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"It does mean that you cannot cite such barges as evidence, as you did."

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To which I must ask, "Evidence as what?" Do you mean evidence for my first reason for comparing the barge design with a streamlined design or for one of the changes in subject which you introduced?

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What I don't see are estimates of the sheer load on a ship moving through storm swells.

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I believe that the sheer stress computation I did was for a ship experiencing a standard L/20 design wave, which I believe is considered the worst case. What other sheer do you feel that I have missed?

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I don't see shock loads, which can be orders of magnitude greater than static loads. And I don't see torsion loads which would, at the very least, wreak havoc on your water seals. In other words, there isn't much useful in your figures.

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I'd be more than happy to consider shock and torsion loads, but have not yet found formula with which to compute these factors.

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Securely fastening the joints isn't going to be possible without steel plates and bolts-- and lots of them.

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I often hear such polemics but I have yet to see any fact and figures with the polemics.

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You must show me the design. You must tell me how it is to be designed to make best use of the joints.

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Unfortunatly, this medium of communcation does not lend itself well to showing designs. But you are correct that seeing a design would be very useful.Let me see if I can describe the joint design for the framework I believe would be quite possible. Consider 3 squared timbers about 1 cubit thick that cross each other at a sample joint. Lets start with a horizontal longitudinal beam that runs the full length of the ship. A transverse beam that runs the full width of the ship crosses over and sets on the top of the longitudinal beam. They are pinned together by a large hardwood dowel that runs up through each beam. As it stands these beams could be able to move in the horizontal plane with the pin as the pivot point.Next a full length vertical timber is placed in one of the 4 verticies formed by the two horizonal beams. And, it is pinned to each of the horizontal beams with dowels that run through each member like the first dowel. The vertical timber will keep the two horizontal beams from moving horizontally. And, The vertical timber would not be able to move in either of the vertical planes with one of the beams because the other horizontal beam would prevent the movement. The dowels and the flat contact surfaces between the timbers would provide much resistance to movement at each joint.
the joint might look something like this:
'''|/
--|--
./|

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Where are your calculations to back that up.

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Don't need 'em.

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You've ignored far too many factors. It is your design, you do the work.

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You have yet to show that the factors I may not have yet included in my design are fatal to the design. There are no facts and figures with your polemics. Polemics without hard evidence doesn't hold much water.{The above message's quotation structure was a big mess, including a big series of nested quotes. Previously, it required the use of the now banished "quote reply" button to get something like that. I have cleaned it up as best I could. I hope the results are true to the intents of the message. Perhaps further editing is called for. -- Adminnemooseus}[This message has been edited by Adminnemooseus, 09-01-2003]

I had calcualted that the stresses under the standard l/20 trachodial wave conditions as 3882 psi. In this article I had erroniously stated that this represented the stress of the ship as supported by two points. And so, I reduced that stress by 1/4 based on a comparison with a cruise ship. However, since I have reviewed the process I realize that I need to use the 3882 psi.This still compares favorably with the maximum stresses for several woods ranging from 6300-10200 psi.PS I have used the PSI of several common woods because the exact idenetity of "Gopher" wood is unknown. I could make reference to some exotic hard woods that range from Opepe (G=.63; 10400 psi) to Ipe (G=.92; 13010 psi) to Kaneelhart (G=.96; 17400 psi). Presumably, Gopher wood was a hard wood and perhaps even an exotic wood, but we dont know. Comparisons to common woods puts computations on the conservative side.

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I notice that cruise ships do have small doors in the sides of the hull about midship. It doesn't matter. These are modern STEEL hulls and the doors are tiny. This is not equivalent to cutting a door in a wooden hull.

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The midway point on the side of a ship between the top and bottom of the ship experiences nearly zero percent of the longitudinal compresion/tension stress. If it is also midway between the two ends of the ship, it also experiences near zero shear stress. Therefore, it hardly matters what the ship is constructed of.The size of the door in cruise ships looks comparatively small in relation to the over all size of the ship. However, they are not all that tiny. You may also want to consider the freight ships that carry cars from Japan to the USA. The cars and all driven on and off the ships through doors in the sides of the freighter.I envision a door some 15 feet tall about 20 ft wide for the Ark. It may have been hinged on the bottom and closed by swinging upward. There could be compression seals all around where the door closed.

In your discussion of what would happen to a boat in a storm without any means of propulsion and control you say that the winds will produce yaw, or spin the vessel around and around. And, while the vessel is crosswise to the wind and waves it will experience high roll that will cause terrible damage to the cargo.I appears to me that you envision the Flood cataclysm is some kind of tropic storm, typhone, hurricane or even a hypercane. I think that this ideas comes from childhood Sunday school stories, i.e. that the Flood was just some overblown, out of control weather condition. I dont believe that the evidence found in the biblical record supports that view.First, the cataclysm begins with the "break up of the fountains of the deep." Anybody know of any 'storm' today that begins that way. After all, what the heck is "the fountains of the great deep' anyway?Second, this break up is associated with the 'opening of the windows of heaven." Anybody had that happen lately? What does it mean anyway?Third, rain falls. This rain is likely associated with the break up and the opening, but no one is certain just what the first two are, so we don't know exactly how the first two cause the third.Fourth, high winds did not start until after causes 1 and 2 had stopped at which time the Ark also came to rest (Gen 7:24-8:4).So, the idea of the Flood being somekind of hypercane, for instance, is not supported by the story. The biblical story describes something which is unknown to us. And, the Ark was agound before the high winds came so it would not be subject to the yaw and spin from that cause.In our discussion of the Flood, we must remember to stick to the narrative of the Bible, even if you don't believe it, because if you don't, you end up creating a strawman argument which is a waste of your precious time.