[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Mon Jun 8 18:59:03 EDT 2015

Kieth,
You have an argument there for sure.
Hank
--------------------------------------------
On Mon, 6/8/15, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Monday, June 8, 2015, 6:52 PM

 Sounds to me that internal engines in
 the pressure hull with through shaft and packing glands are
 the only way to go.

 Keith T 

 Private via Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

 >Hang on, I'm not understanding Brian's suggestion. What
 exactly are the "oil traps"?
 >
 >
 >
 >> On Jun 8, 2015, at 5:26 PM, hank pronk via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 >> 
 >> 
 >> Actually Brian's idea is picking up steam in my
 mind!  The power loss your experiencing would not
 happen if the motor is open to the water because the motor
 is truly equal on both sides.    
 >> 
 >> Hank--------------------------------------------
 >> On Mon, 6/8/15, hank pronk via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 >> 
 >> Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at
 Seneca
 >> To: "Personal Submersibles General Discussion"
 <personal_submersibles at psubs.org>
 >> Received: Monday, June 8, 2015, 5:16 PM
 >> 
 >> 
 >> Alec,
 >> I have the same problem with my drive on Gamma,
 >> when returning to the surface the shaft tube is
 under
 >> pressure.  I have a ball valve mounted to the
 tube and even
 >> a month later there is pressure until I open the
 ball
 >> valve.  I have tried a softer compensation
 bladder with no
 >> luck.  There has to be an air pocket that we
 are not
 >> getting rid of.  Brian's suggestion is not bad
 at all,
 >> forget the bladder and rig an open hose with traps
 so the
 >> oil can not escape.  There would be an air
 space trapped
 >> between the oil and water in the length of
 tube.  That air
 >> bubble would simply move in two directions
 depending on
 >> depth.  A very simple solution, more tricky
 for you because
 >> your motors rotate.  I think I will test this
 idea since I
 >> have my tail assembly off for repairs anyways.
 >> Hank--------------------------------------------
 >> On Mon, 6/8/15, Alec Smyth via
 >> Personal_Submersibles <personal_submersibles at psubs.org>
 >> wrote:
 >> 
 >>  Subject: Re:
 >> [PSUBS-MAILIST] Dive report: Snoopy at Seneca
 >>  To: "Personal Submersibles General
 >> Discussion" <personal_submersibles at psubs.org>
 >>  Received: Monday, June 8, 2015, 4:48 PM
 >> 
 >>  OK, let me
 >> 
 >> try to reason this through again. Lets say the
 standard
 >>  trolling motor shaft seal is watertight to
 50
 >> feet, and that
 >>  initially I had 1 cubic inch
 >> of bubble in the system. Dive
 >>  to 250 feet
 >> and what I would have thought would happen is
 >>  that the 1 cubic inch of air would be
 reduced
 >> to 1/8th in3
 >>  due to 8 atmospheres of
 >> pressure increase. I would have
 >>  expected
 >> that the compensation bladder would have just been
 >>  squeezed by that volume, and that upon
 >> surfacing the bubble
 >>  would go back to 1 in3
 >> and the pressure in the motor to 1
 >>  atm.
 >> However, what we found was that the motor upon
 >>  surfacing was significantly pressurized. The
 >> compensation
 >>  bladder (i.e. hose) was
 >> visibly distended by internal
 >>  pressure upon
 >> surfacing. There was no leak at the hose
 >> 
 >> clamps, but oil was leaking from the shaft seal.
 >>  Since there was over-pressure
 >> 
 >> surfaced, clearly water had to have entered the
 system
 >>  during the dive, and as the hose clamps were
 >> leak free and
 >>  the seal was not, I suspect
 >> the seal. Now the question is
 >>  why water
 >> would get in. Bubble greater than the compression
 >>  range of the hose? Seal offering less
 >> resistance than the
 >>  hose to compression?
 >> Shaft pumping water under the seal
 >>  during
 >> operation due to abrasions? Thermal contraction?
 >>  I'm actually not sure - any theories are
 >> welcome. One
 >>  interesting detail - the stern
 >> thruster, which was not
 >>  working due to the
 >> issue with the speed controller, did not
 >> 
 >> have any oil leaks. Both side thrusters,
 operating,
 >>  did.
 >>  The side
 >>  thrusters being feeble can be explained by
 >> pressure on their
 >>  seals, or just by their
 >> age and related wear on the
 >>  commutators. I
 >> will be changing them, or at least their
 >> 
 >> internals.
 >> 
 >>  Best,
 >>  Alec 
 >>  On Mon, Jun 8, 2015 at
 >> 2:54
 >>  PM, Jon Wallace via
 >> Personal_Submersibles <personal_submersibles at psubs.org>
 >>  wrote:
 >> 
 >>    
 >>  
 >>    
 >>    
 >>    
 >>  
 >>    
 >> 
 >>    
 >>    It sounds like at some point water
 pressure at
 >> the
 >>  seal was able
 >>    
 >>    to compress the bubble of air in the
 tube,
 >> the
 >>  opposite of what
 >>    
 >>    was expected.
 >> 
 >>        
 >> 
 >>        I'm kind of stumped by
 >> the description of the
 >>  motors
 >> performance
 >>        being
 >> "feeble" however.  This couldn't
 >>  have been primarily due to
 >>  
 >>      pressure I don't think. 
 Also,
 >> isn't an easy
 >>  fix just to
 >> "clamp"
 >>        the
 >> tube any place where liquid appears assuming the
 >>  tube is held
 >>    
 >>    in a vertical position and the bubble
 is at
 >> the top
 >>  (ie vise grip
 >>    
 >>    the tube).
 >> 
 >>        
 >> 
 >>        Jon
 >> 
 >>        
 >> 
 >>        
 >> 
 >>        On 6/8/2015 12:01 PM,
 Brian
 >> Cox via
 >>  Personal_Submersibles wrote:
 >> 
 >>      
 >>      
 >>    
 >>    
 >>          Hmm,
 >> guess I'm not getting what is
 >> 
 >> happening
 >>           
 >>          Brian
 >> 
 >> 
 >>          
 >>  
 >>      
 >>      
 >>      
 >> 
 >>    
 >> 
 >> 
 >> 
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