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Re: [PSUBS-MAILIST] credentials
Hey, I had me a bad case of credentials once. Don't know whether I got them cleaning out a pool or siphoning gas with a hose. Somebody needs to come up with a salve or something. This bunch is the greatest! Mark Steed
---------- Original Message ----------------------------------
From: "Herve" <caribsub@coqui.net>
Reply-To: personal_submersibles@psubs.org
Date: Thu, 21 Nov 2002 17:43:22 -0400
>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
>>
>>
>>
>
>