[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Tue Jun 9 00:21:15 EDT 2015

How about an internal pressure hull mounted diesel generator and batteries
with cable thru-hulls to the main surface drive motor and the side
thrusters?  Exhaust and intake pipes installed in a tail fin/rudder. The
genset powers the hp compressor while powering the main motor to and from
the dive site.

Why not mount the motors within pressure cans and power the props through
magnetic couplers?

Tim

-----Original Message-----
From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org]
On Behalf Of hank pronk via Personal_Submersibles
Sent: June-08-15 3:59 PM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca

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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 >>
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 >>
 >>
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