RE: [PSUBS-MAILIST] Hydraulic Drive Unit

["Gary R. Boucher" <engineer@sport.rr.com>]

Storm,
     You may be slightly off track in your view of the discussion.  I am 
neither for nor against electric motor direct drive.  I am neither for or 
against hydraulic drive.  I am against the concept of labeling any viable 
engineering approach as inefficient, a poor choice, or inferior.  I think 
that for most people building a first sub, hydraulics is not a good 
choice.  But, direct drive through the hull, nozzles, and several other 
approaches are not good either for beginners.  I suggested to SubQuandary 
that he use trolling motors that have been pressure compensated because it 
is probably the easiest approach to implement, if one is just getting started.
     My main point, that was apparently missed by some was centered on a 
simple concept.  That being that engineering is a process of laying all 
viable options out on the table and working through a series of compromises 
to come up with a optimized design.  This does not necessarily mean a 
system that gives propulsion for the longest time on a given battery 
system.  The use of any propulsion system is based on numerous factors, 
many of which are not obvious, until the builder starts to lay out a design.
     I do not use exterior battery pods.  One could easily say "That is not 
a good idea because... "  As I said before "Don't make blanket statements 
until you know the rational."
     I apologize if this discussion has offended anyone.  However, I am of 
the belief that such rhetoric is good and valuable to those who listen to 
the debate and use what is said to make informed decisions.  My desire here 
is to encourage anyone contemplating the construction of a Psub to think, 
but leave their options open.  Weigh everything in terms of the overall 
design objectives.
     Where is that site that will pay us for the video???

Gary Boucher


At 10:05 PM 11/20/2002, you wrote:
>Sorry, can't hold back any longer.
>You are both obviously inteligent guys with relevant experience. You are
>both of the opinion that electric is a simpler option for propulsion. That
>said why get hot under the collar if subquandry wants to have a play with
>hydraulics. Maybe he makes hydraulics for a living, maybe he's got a heap of
>surplus parts sitting around. Practical or not FREE always moves it up the
>list for me :-)
>You both know the pro's and con's, and subquandry has i'm sure got all the
>info he wants for now. Wether one is better or not is irrelevant. Any
>technical application is only as good as it's last improvement. Who knows if
>we work out how to build a boat big enough and find a crew crazy enough to
>sail to the end of the world we might prove the world is round!
>
>As for the pissimg contest there are a couple of sites on the net that would
>pay good money for footage of that so if you let me know where and
>when.......
>
>
>Life is short, have a smile
>
>Storm