Atheists believe the size of the ark would have caused it to break apart in the stormy seas, but the Bible never says the waves were raging or even that the water was choppy. The Bible simply says it rained until nobody had a ladder tall enough and they all drowned. The sea upon which the ark floated was as calm as your grandmother on valium. Aside from this, ship building experts (see web site below.) have determined that a craft the size of the ark could have easily made the voyage described in the Bible.
www.worldwideflood.com/ark/safety_aig/safety_aig.htm
Rebuttal?
From:
http://www.freeratio.org/thearchives/showpost.php?p=985297&postcount=6Analysis by George W. Herbert, moderator of sci.space.tech and holder of a degree in naval architechture:
Quote:
>
http://www.answersingenesis.org/home..._arksafety.aspSure...
On first inspection:
0. Editorial comment
This paper was written by people who looked at a naval
architecture text book and did not understand what they
were seeing; it uses terminology from the profession
but not correctly, and does not use the right analysies.
Either the translation was grossly incorrect or the
paper was the work of not particularly attentive undergrad
students, given that the authors were supposedly at the
Korea Research Institute for Ships and Engineering.
1. "Draft and center of gravity" section
Displacement is given as:
(delta) = 1.025 L B d
That is the correct formula, for a brick.
Perhaps a bad sign of things to come.
Real ships are not perfect rectangular prisms;
they have rounded shapes, and the actual
displacement is some fraction depending on
the curvature of the ship, keel deadrise,
and numerous detail factors. These combine
to give a 'block coeficient' Cb which is simply
the actual volume divided by the volume of
the rectangular shape of the same length,
breadth, and depth. Cb varies from about 0.9
(really blocky huge oil tangers) to 0.55
(light destroyers) but is not 1.0 even for
rectangular barges, which have *some* rounded
off parts...
2. also in "draft and center of gravity" section
These guys calculate the height of the center of
gravity... which is good, and they don't seem to
have completely blown it, but the simplicity of the
analysis jumps out.
*No* mention is made of the height of the center
of buoyancy (the geometric centroid of the displaced
volume).
*No* mention is made of the equally important
Metacentric Height. The metacenter (M) is the imaginary
point around which the geometric center of the
waterplane area rotates as the ship rolls and
pitches. As that area shifts, the actual dynamic
stability of a ship depends on how far above
the center of gravity the metacenter is found.
The metacenter is some distance above the center
of buoyancy, and has to be calculated.
No real ship other than a submarine has its
center of gravity under its center of buoyancy.
The actual moment arm for stability calculations
is the height from the center of gravity G to
the metacenter M (GM).
3. "Comparative hull forms" section
Huh?
Comparative hull dimentions table, maybe.
"Hull Form" implies looking at the curvature,
block coeficient, etc.
4. "Method of Evaluation" subsection in "Seakeeping Performance" section
"A widely used strip method"...
These guys have not even determined KB, BM, or GM, and they
are performing computational motions analysis?
Er.
Ok. This fails the scratch and sniff test, but the method used
is not grossly inappropriate.
5. "General" subsection of "Structural Safety" section
These people do not understand wooden shipbuilding.
Using the terms associated with steel ships is
a gross mistake.
6. "Structural analysis of Ark" subsection of "Structural Safety" section
This fails the scratch and sniff test.
They plug the numbers in to a FEA rather than presenting the basic
by hand back of the envelope calculation. Bzzt.
They assume that they could rigidly attach a 2 dimentional girder
structure to a wooden "shell" ... no mention of how this is made
strong in shear, which is why thick hulled wooden ships are not
made that way.
They do not list the scantlings (thickness and dimentions of
the hull, longitudional and transverse frames, etc).
Without knowing what the actual dimentions are nobody
can crosscheck their numbers. Showing computer program
output without scantlings is the equivalent of lying
with graphics.
"Structural Safety Index" is introduced without any
foundation for what it is supposed to represent
in the analysis and optimization.
7. "Righting Arm" calculations in "Overturning Stability" section
Ah, now we get the metacenter. Except they're calling it Z,
instead of M, and they *integrate* to find the height rather
than simply pulling "Principles of Naval Architecture" off the
shelf and plugging the one line formula in... D'oh.
8. "Overturning stability Index" in "Overturning Stability"
What is this 'overturning stability index' and where is it
coming from? The term is not defined, referenced, etc.
It is not a term of the art in the field.
9. "Voyage Limit of the Arc"
Calculated for rolling motion. Never calculate in roll;
always calculate in pitch and sagging/hogging moment.
"Thickness of wood..." thickness *where*?
10. conclusions
Yet more of these imaginary safety indexes, which are not defined.
Yet more graphs without any supporting explanation of what the
axies mean.
11. my conclusion
This paper fails to show its work.
Almost none of its stated conclusions are supported
with enough documentation to review and evaluate for
technical correctness. Were this a student paper
it would fail on that basis, and it would never
be published in a naval architecture journal for
the same reason.
This paper fails to show basic familiarity with the
standard terminology, rules of thumb, and standards
of practicing naval architects, much less student
naval architects.
This paper fails to reference any of the standard
textbooks in ship design (Such as, Principles of
Naval Architecture 1990 ed). While papers have
certainly been written without reference to PNA,
the inclusion of a bunch of more specific references
without any reference to or use of the basic methods
and overview survey in PNA is bizarre.
