Re: [PSUBS-MAILIST] Drive shaft alignment & sopport.

["Keith Gordon" <searov@xtra.co.nz>]

I have found the arguments over the past few days most interesting and
informative however feel I must comment. With regard to Dr Walter Stark's
statements I would suggest those interested check on his past achievements
as the developer of the Electrolung and many other underwater technology
achievements. He has quite a track record. Secondly - having been involved
with the old Pisces submersibles and  ROV technology I would suggest those
interested study  what has worked in the past  and keep it simple!!! Why
re-invent the wheel! However am enjoying the argument.

Keith Gordon
----- Original Message -----
From: "Gary R. Boucher" <engineer@sport.rr.com>
To: <personal_submersibles@psubs.org>
Sent: Saturday, November 23, 2002 6:38 PM
Subject: Re: [PSUBS-MAILIST] Drive shaft alignment & sopport.


> Walter,
>
>      What you think of my judgement is your business and not a major
> concern to me.  This open discussion, I hope, has been informative for
> those choosing to read it.  Anyone reading these threads has an
opportunity
> to make judgements as to what they find useful or useless.  I have a
> feeling that the thru-hull issue is probably not the only practice of
yours
> that I would take issue with.  But, at this point what the PSUBer decides
> to do is up to their own judgement.  All the points and counter points
that
> I know of on these issues have been made.
>      Unless my BS warning light once again illuminates brightly, I will
> attempt to avoid "Beating these Dead Horses."
>
> Gary Boucher
>
>
> At 10:19 PM 11/22/2002, you wrote:
> >Gary,
> >
> >On hydraulic propulsion I do think it falls in the category of
> >unnecessary complexity and expense with a performance penalty as well..
> >As for your engineering judgement outside this I know nothing and have
> >no opinion. My comments on over engineering were generic to a commonly
> >encountered circumstance not a judgement directed at any individual.
> >
> >On the matter of the thru hull cable fitting your concerns seem to be
> >based on a rubber insulated cable.  This is the type I specifically
> >advised against.  The type I did recommend has a solid PVC outer
> >insulation.  PVC is not only much stronger it slowly cold flows where
> >compressed by the O-rings.  This locks it into place very securely.  The
> >50 lbs. extrusion force mentioned in the example is far below  what it
> >will withstand.  Nothing you have offered in the way of theoretical
> >dissent contradicts this and it is easily tested.  This is beginning to
> >look like an example of the NIH factor.
> >
> >NIH is often the impetus to coming up with complicated solutions and
> >ignoring simple proven ones that are already available.  NIH is short
> >for Not Invented Here.
> >
> >Walter Starck
> >Golden Dolphin Video CD Magazine
> >The premiere publication of diving and the ocean world.
> >www.goldendolphin.com
> >
> >
> >
> >
> >----- Original Message -----
> >From: "Gary R. Boucher" <engineer@sport.rr.com>
> >To: <personal_submersibles@psubs.org>
> >Sent: Saturday, November 23, 2002 10:35 AM
> >Subject: Re: [PSUBS-MAILIST] Drive shaft alignment & sopport.
> >
> >
> > >
> > > >Gary,
> > >
> > > Starck wrote:
> > >
> > > >I do confess the comment you so object to was a bit tongue in cheek
> >to
> > > >see if you would bite.  If you wish to take it seriously however it
> >is
> > > >not entirely BS.  Certainly engineers do make possible much truly
> >superb
> > > >technology but this does not obviate abundant examples of  poor
> > > >engineering involving needlessly complicated ways of doing things and
> > > >failing to take advantage of  readily available well proven
> >solutions.
> > >
> > > You're actual tongue and cheek, yet not entirely BS comment, is held
> >by a
> > > number of people I have met.  One close friend feels that I am the
> >only
> > > engineer he has any respect for.  He can't stand all the others.  The
> > > fellow does superb work and is the best craftsman I have even known as
> >he
> > > builds aircraft from the ground up.  These are not kit planes, he does
> > > extensive modifications of existing high-performance planes and
> >constructs
> > > some of his own designs.  I have a great deal of respect for his
> >mechanical
> > > judgement, yet there is an element missing.  He never calculates
> > > anything.  He shoots from the hip and it may someday get him in
> >trouble.
> > >
> > > You apparently, because of my use of hydraulics, feel that I am a
> >person
> > > that applies needlessly complicated approaches to simple problems.  I
> >will
> > > let my work stand for itself.
> > >
> > > >As for reliability of the thru hull cable fitting I described your
> > > >concerns are justified on the basis of not trusting your life to info
> > > >posted on the internet by parties unknown.
> > >
> > > Your posting on the Internet has nothing at all to do with my
> >unwillingness
> > > to adopt your method for deep water thru-hull penetration.  Your
> > > credentials have nothing to do with it either.  If you had a doctorate
> >in
> > > mechanical engineering with extensive work in the field, that would
> >not
> > > mater to me either in this case.  I will let your note continue.
> > >
> > > >You seem to be saying though, that you only trust theory not the
> >results
> > > >of empirical experience.
> > >
> > > If you knew me better you would not even suggest such.  I am a strong
> > > believer in empirical experience and judgement.  Much of my work is
> >based
> > > on intuition.  I know when to go with intuition and I know when to
> >shift to
> > > hard numbers.  No one I know and no body that works with me thinks of
> >me as
> > > a theoretical engineer.
> > >
> > > >For the most part we really
> > > >don't truly know why things work but just that they do.  If on the
> >other
> > > >hand, what you are referring to as theory is just the principles and
> > > >formulas which  quantify  our empirical knowledge please do apply
> >them
> > > >to the problem at hand.
> > >
> > > You seem to be trying to parse my reasoning into two categories.  One
> > > practical and the other theoretical.
> > >
> > > >   The parameters are simple, force, coefficient of friction, and
> >modulus
> > > > of elasticity.
> > > >    I have stated what I have
> > > >found from experience.  You imply theory does not support this.  I
> >would
> > > >be genuinely interested in learning what theory, how it differs, and
> > > >what safe limits it predicts.
> > >
> > >      Part of my profession is teaching physics at the university
> > > level.  Almost every day I deal with factors such as force,
> >coefficients of
> > > friction, and Young's Modulus.  All the problems work out so nicely on
> >the
> > > board.  All the numbers agree to three decimal places with the answers
> >in
> > > the back of the book.  It would give the student the impression that
> > > everything in physics is just so precise.  But, the truth is far from
> > > this.  Translating pure theory to practice in the real world is not so
> > > one-to-one as a person might think.  These factors are good for
> >predicting
> > > estimates and ranges of expected performance, but often fall way short
> > > because the simple parameters do not exactly match or there is or can
> >be
> > > many factors too complex to accurately estimate.
> > >      In the case of the wire mentioned in an earlier post (0.40 inches
> >in
> > > diameter) the load calculated was 55 pounds.  That means that the
> >wire's
> > > insulation, not the wire itself must be able to take a compressive
> >load of
> > > this value.  Should there be any exceptions in any of the parameters
> >or
> > > just a flaw in the wire's insulation itself, failure could easily push
> > > uninsulated wire through a hole intended for the  insulated wire's
> >diameter.
> > >      I can run numbers on the O-ring penetration using estimates for
> > > coefficient of friction and the like.  But my person intuition, my
> > > engineering intuition, my knowledge of how such parameters vary in
> >real
> > > live tells me to not get in that sub at that depth.  You are simply
> >making
> > > a jacket of rubber into a pressure bearing structural component.
> > >
> > >      If you want a good example of rubber failure consider how many
> > > unwanted births are caused by some component made of similar material
> > > failing when it is supposed to hold up under the rated load!
> > >
> > > Gary Boucher
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Let me state just a few, but I am sure, not all of the not so simple
> >factors.
> > >
> > > Coefficient of friction varies greatly with age of a material,
> >lubrication,
> > > moisture content etc.  Wire insulation properties also vary with age
> >and
> > > conditions.  Given the example of a 0.4 diameter wire I used in a
> >previous
> > > post, the loading on the insulation is about 44 pounds per lineal
> > > inch.  Assuming a "Wet" coefficient of friction for rubber against
> >O-Ring
> > > of 0.6 the loading will be around 73 pounds per lineal inch.
> > >      O-Rings are not intended for
> > >
> > >
> > >
> > >
> > > >Walter Starck
> > > >Golden Dolphin Video CD Magazine
> > > >The premiere publication of diving and the ocean world.
> > > >www.goldendolphin.com
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >----- Original Message -----
> > > >From: "Gary R. Boucher" <engineer@sport.rr.com>
> > > >To: <personal_submersibles@psubs.org>
> > > >Sent: Saturday, November 23, 2002 12:01 AM
> > > >Subject: Re: [PSUBS-MAILIST] Drive shaft alignment & sopport.
> > > >
> > > >
> > > > >
> > > > > Starck Wrote:
> > > > >
> > > > > >If you enjoy problems and complicated expensive solutions
> >complete
> > > >with
> > > > > >all sorts of reasons why what works in practice is no good in
> >theory
> > > >and
> > > > > >should be ignored consult an engineer..  They can  solve problems
> > > >that
> > > > > >don't even exist and create new ones no one else has encountered
> > > >before.
> > > > >
> > > > > That is absolute B.S.  No matter what your profession is, you find
> > > >those
> > > > > who are incompetent, unknowing, and irrelevant.  The engineering
> > > >profession
> > > > > is no exception.  However, what I have found through the years
> >over
> > > >and
> > > > > over is people who have limited knowledge of technical issues who
> >make
> > > > > broad-ranging and very verbal assumptions.  These people, because
> >they
> > > >do
> > > > > not completely understand the underlying theory, believe that
> >those
> > > >who do
> > > > > understand and can employ that theory are somehow living in their
> >own
> > > >world
> > > > > using tools that are irrelevant to good design practice.
> > > > >
> > > > > I will give a case in point.  I know someone that pressure chamber
> > > >tested a
> > > > > submersible window design using Lexan.  The window was one-time
> >tested
> > > >to
> > > > > beyond the rated operating depth of the sub.  The Lexan actually
> >had a
> > > > > noticable bow inward under pressure creating a convex/concave
> >window.
> > > >The
> > > > > logic here was simple and of course not needing any real theory,
> > > >certainly
> > > > > not any engineering expertise.  The logic simply put was that, if
> >the
> > > > > window did not fail under one cycle of pressure, somewhat over the
> > > >rated
> > > > > operating depth of the sub, coupled with the fact that Lexan
> >seemed a
> > > > > wonder material and would never actually break, everything was
> >fine.
> > > >This
> > > > > is a typical assumption made by someone that does not understand
> >the
> > > > > properties of the material.  "No engineering theory needed here.
> >We
> > > >just
> > > > > proved that it will work.  We built 100 of them and never had a
> > > >problem."
> > > > >
> > > > > There is NO way I want to go down below very shallow depths in a
> >sub
> > > >with
> > > > > thin Lexan windows.  Likewise, there is NO way I want to go down
> >to
> > > >1000
> > > > > feet in a sub that uses wire penetraters made from flair fittings
> >and
> > > > > O-Rings relying on nothing but the wire's insulation to keep the
> >water
> > > >out.
> > > > >
> > > > > You do not have to be an "engineer" to construct a safe
> >submersible,
> > > >if you
> > > > > find outside help from qualified individuals, but the PSUBer has
> >the
> > > > > responsibility to determine who to get advice from.  After many
> >years
> > > >of
> > > > > this type of work, I feel that I have just about reached the level
> > > >where I
> > > > > know what I don't understand and where to get good help.
> >Basically, I
> > > >am
> > > > > NOT an expert.  But, I know where to find good advice.
> > > > >
> > > > > Gary Boucher
> > >
> > >
>
>
>