[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Tue Jun 9 08:43:19 EDT 2015

Would it not be an issue that oil is lighter than water, and therefore
would just float out?

On Mon, 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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