Re: [PSUBS-MAILIST] credentials

["Herve" <caribsub@coqui.net>]

Credentials, credentials.....so what?
those who have "true"credentials dont need to justify themselves, re the
endless list of vessels and subs built by "credential" people that lay on
the bottom of the sea, and what about creations and machines built by non
credential individuals.
Real credentials are referrals, not only piece of papers in a nice frame on
a wall.
I dont think this forum is for anyone to talk about his credentials, unless
others talk about it.
Herve
----- Original Message -----
From: "Ray Keefer" <Ray.Keefer@Sun.COM>
To: <personal_submersibles@psubs.org>
Sent: Thursday, November 21, 2002 1:28 PM
Subject: Re: [PSUBS-MAILIST] Hydraulic Drive Unit


> Hi Carl,
>
> I am one of the ignorant ones also. That is why I host this site. To
> learn from others, whether they are credentialed by experience or
schooling,
> I don't care.
>
> But every tid bit I hear about I weigh and judge for usefulness in my
> projects. I am responsible for my final design. I like hearing about
> other's concepts however the designs I will come up with will have
> elements that fit my need, and mine only.
>
> Regards,
> Ray
>
> > Date: Thu, 21 Nov 2002 00:31:50 -0700
> > From: Coalbunny <coalbunny@vcn.com>
> > X-Accept-Language: en
> > To: personal_submersibles@psubs.org
> > Subject: Re: [PSUBS-MAILIST] Hydraulic Drive Unit
> > Content-Transfer-Encoding: 7bit
> >
> > I come here because I like the idea of mini subs.  I guess us
> > non-credentialed folk ain't got no business here then.
> > Carl
> >
> >
> > Walter Starck wrote:
> > >
> > > Gary,
> > >
> > > I don't have the time nor inclination to get into a pissing contest
over
> > > credentials.  I understood this thread to be about the putative merits
> > > hydraulic driven propulsion for PSubs.  I offered the opinion this
> > > approach offered no real advantage and considerable disadvantage as to
> > > cost, total system bulk, complexity and efficiency.  I also said they
> > > will work and work well but in view of the disadvantages they are not
> > > the best solution.
> > >
> > > Thus far your arguments for hydraulic propulsion are all hypotheticals
> > > addressing non-problems while your objections to straight motor drives
> > > are in regard to problems that in actual practice have been solved for
> > > many years.  Literally thousands of  successful PSubs, ROVs, DPVs,
> > > research submersibles and larger military and commercial submarines
have
> > > been built.  Only a tiny minority employ hydraulics for propulsion.
> > > Propulsion system leakage and  reliability are rarely problems and in
> > > those rare events are neither disasterous nor difficult to fix.
> > >
> > > I am not familiar with your particular application and have no opinion
> > > in that regard but as a general solution for PSubs which is what the
> > > discussion seemed to be about, hydraulic propulsion would be a poor
> > > choice.
> > >
> > > 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: Thursday, November 21, 2002 10:28 AM
> > > Subject: Re: [PSUBS-MAILIST] Hydraulic Drive Unit
> > >
> > > > Walter Starck wrote:
> > > >
> > > > >Gary Boucher wrote: " I get somewhat irritated when people that
have
> > > not
> > > > >gone through this process sit back like armchair quarterbacks and
> > > make
> > > > >broad reaching
> > > > >technical statements."
> > > > >
> > > > >I do too but with over 40 years experience in designing, building,
> > > > >operating and maintaining a wide variety of underwater and marine
> > > > >equipment I have gone through the process.
> > > >
> > > > I have no idea what your credentials are.  Forty years of
"experience"
> > > is
> > > > pretty vague, but lets say that you have experience in actual design
> > > and
> > > > construction of manned submersible propulsion systems.  The issue
that
> > > I
> > > > raised stands.  You are making a blanket condemnation of hydraulic
> > > > propulsion and this is an uninformed declaration.
> > > >
> > > > >Alec Smythe Wrote: "In an earlier post Gary pointed out that in
> > > > >hindsight, he recommends compensated trolling motors for their
> > > > >simplicity."
> > > >
> > > > Lets set the record straight here.  I do recommend pressure
> > > compensated
> > > > trolling motors for most applications where people are designing
> > > > PSUBS.  There is a simple reason for this.  It is the easiest
approach
> > > for
> > > > the PSUBer who has limited knowledge of other approaches.  A
thru-hull
> > > > shaft is probably the very last thing I would recommend for these
> > > > people.  I don't recommend hydraulics for every application.  I
don't
> > > > recommend hydraulic propulsion for most subs.
> > > >
> > > > You probably have no idea what the design philosophy of my sub is.
> > > You
> > > > have no idea what the intended purpose of my design was, or is.  You
> > > are
> > > > placing yourself in the position of an expert and basically saying
> > > that all
> > > > hydraulic propulsion is a bad idea.  I strongly disagree.
> > > >
> > > > If hydraulic propulsion is such a bad idea, why don't you take this
> > > > campaign to the manufactures of thrusters that are driven by
hydraulic
> > > > fluid.  They are on the market.  They must sell because they still
> > > make them.
> > > >
> > > > >This seems to agree completely with what I have said although Gary
> > > now
> > > > >seems to disagree.
> > > >
> > > > No, no change in my opinion.  The main reason that I would rethink
my
> > > > design if I had it to do again is weight.  I am marginal on my
weight
> > > and
> > > > would for that reason like to have some extra buoyancy provided by
> > > motor pods.
> > > >
> > > > >Sean Stevenson wrote: "For the homebuilder, overcoming the
efficiency
> > > > >issue is the only real hurdle for emplying a hydraulic system."
> > > > >This like saying overcoming gravity is the only real hurdle to
> > > building
> > > > >a flying saucer.  High friction losses are inherent in hydraulics.
> > > For
> > > > >brief or intermittent operation or anywhere power is not limited
this
> > > > >loss may not be important.  In small submersibles however,
available
> > > > >power is a limiting factor and taking a 30% or more efficiency hit
on
> > > > >usage is an important consideration.
> > > >
> > > > I will quickly admit that efficiency can be an issue.  Whether this
is
> > > a
> > > > deciding issue or not cannot be judged by anyone without first fully
> > > > understanding what the design emphasis is.  Engineers learn very
> > > quickly
> > > > that nobody can build the perfect car, airplane, boat, submarine,
> > > > etc.  Compare a Jaguar  to a Lincoln.  Each is an excellent car in
its
> > > own
> > > > right.  Each has a totally different functional design, a totally
> > > different
> > > > purpose.  If fuel efficiency is your issue, buy a Taurus.
> > > >
> > > > Each design is an optimization of purpose based on a very extensive
> > > set of
> > > > tradeoffs.  The engineer's main purpose is to make judgements as to
> > > what is
> > > > important and what is not, what is going to promote the design
> > > philosophy
> > > > and what is not.  Good engineers are going to weigh the merits and
> > > balance
> > > > the pros and cons.
> > > >
> > > > I hear a lot of talk about propulsion on PSUBS.  I hear some really
> > > > outlandish proposals.  Most are not feasible, but I seldom discard
> > > these
> > > > ideas, in that I put many of them on the shelf for later
> > > consideration.
> > > >
> > > > >Carsten Standfuss obviously understands the issues.
> > > >
> > > > Carsten apparently is a good engineer and builder.  But, just
because
> > > he
> > > > elected to not use hydraulics for his controls does not make, in
> > > itself,
> > > > hydraulic controls a poor decision.
> > > >
> > > >
> > > > Gary Boucher
> > > >
> > > >
> >
> > --
> > "You delight not in a city's seven or seventy wonders, but in an answer
> > it gives to a question of yours, or the question it asks you, forcing
> > you to answer, like Thebes through the mouth of the Sphinx." -- Kublai
> > Khan
>
>
>