[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Sat Jun 6 12:55:07 EDT 2015

DW's come from Canada :-)--------------------------------------------
On Sat, 6/6/15, Private 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: Saturday, June 6, 2015, 10:45 AM

 Thanks for the offer, but
 Snoopy is 12 volt. The controllers are Zavsza brand called
 Canakit. These Canadians... nothing good comes from them,
 eh?

 > On Jun 6, 2015, at 8:20 AM, hank pronk via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 > 
 > Alec,
 > I don't know what type of speed
 controller you are using, but I like and use Curtis golf
 cart controllers.  They are rated for huge amperage and
 seem bullet proof.  I have an extra 36V controller I can
 send you to try out.  They use a 10 OHM potentiometer for
 the throttle.  They also have a battery protection mode, a
 sort of get home conservation mode.  
 >
 I labeled the motor in Gamma for a jumper cable, so that I
 can get home without the controller.  As you said it is
 electronic and it will fail.
 > If you
 want the controller send your address of list.
 > Hank
 >
 --------------------------------------------
 > On Fri, 6/5/15, Alec Smyth via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 > 
 > Subject:
 [PSUBS-MAILIST] Dive report: Snoopy at Seneca
 > To: "Personal Submersibles General
 Discussion" <personal_submersibles at psubs.org>
 > Received: Friday, June 5, 2015, 6:16 PM
 > 
 > Hello friends,
 > I just got back from a dive trip to Seneca
 with
 > Dan Lance and thought I'd
 share how it went. This was
 > supposed to
 be a two sub trip with Scott Waters, but
 > unfortunately a business emergency
 intervened and it ended
 > up being just
 Snoopy.
 > On the way up the weather was
 terrible, with
 > driving rain so heavy I
 could barely see the lines on the
 > road.
 It had been raining heavily for several days
 > previously. Three times there were
 emergency announcements
 > about floods,
 large hail, and damaging winds, and the closer
 > I got the harder it rained. The problem
 with all that rain
 > is that in your
 typical lake, the runoff ruins visibility
 > for weeks. That is what happened last year
 when Trustworthy
 > and Snoopy
 rendezvoused at Summersville Lake, and it looked
 > very much like this would be a repeat.
 I'm happy to say
 > Seneca must be
 rain-proof, because the deluge only reduced
 > the visibility in the top fifty feet or
 so, and even those
 > were clearer than
 most lakes.
 > Here's a few things we
 learned:
 > 1) Of props and shroudsThe
 stern
 > thruster speed control was dead
 on arrival, although I had
 > tested it
 successfully before leaving. I opened up the
 > enclosure, pressed down all the spade
 connectors, and found
 > it now worked -
 so attributed the issue to road bumps.
 >
 However, it died within a minute on the first dive. I had
 a
 > spare speed controller, so switched
 it out. 
 > The replacement died within
 five minutes on the
 > second dive. This
 time at least the cause was obvious, the
 > prop was jammed by weeds. The current
 Minnkota props have a
 > little twist at
 the end of the blades, and Snoopy's
 >
 shroud is made with almost no clearance. The little twist
 to
 > the blade tip causes any object
 coming between prop and
 > shroud to jam
 tight, and had already smoked one controller
 > during the convention in the Keys. I'm
 going to put the
 > prop on the lathe and
 take off the tips to eliminate the
 >
 pinching effect and to reduce the amperage draw a little
 so
 > the motor goes lighter on the speed
 controller. By the way,
 > the speed
 controller was protected by a fuse rated a little
 > below the controller spec current draw, so
 perhaps those
 > specs are optimistic.
 Anyway, as a result of the double
 >
 failure all of our dives were done on just the side
 > thrusters because I was out of spare speed
 controllers.
 > Lesson for next sub:
 Design the electrical system with a
 >
 controller bypass, so I can operate thrusters with simple
 > on/off switches if a speed controller
 fails. They're
 > electronic, they
 will fail.
 > 2) Of air bubbles in
 compensation oil
 > Snoopy is now
 routinely diving deep (250 ft) and
 > this
 has showed up a puzzling issue with the thrusters. They
 > were feeble during dives, one died
 altogether on one dive,
 > and they kept
 coming up leaking oil. At first we thought the
 > seals were failing, perhaps due to some
 chemical
 > incompatibility. We found
 suitable seals at an Amish farm
 > supply
 store that sold things like tractor spares (viva
 > trolling motor simplicity!) When I
 disconnected the bladder
 > hose I got
 quite well sprayed with oil. The motor turned out
 > to be pressurized. 
 >
 Previously, I thought if one had a small quantity
 > of air left in the system it would not be
 an issue so long
 > as the compression
 volume of that air could be handled by
 >
 the flexibility of the hose (aka compensation bladder.)
 > Wrong. I now think what happens is that if
 the dive exceeds
 > the pressure rating of
 the shaft seal and there is a bubble
 > of
 any size, you will get water added to the oil and the
 > bubble stores the pressure. Upon
 surfacing, the bubble
 > squeezes oil and
 water back out until the pressure in the
 > motor falls to the "cracking
 pressure" of the
 > seal. Thus, you
 get an oil leak even though the seals are
 > fine. Lesson: Zero tolerance with oil
 bubbles, even a small
 > bubble is
 unacceptable if you are diving deep. I'm going
 > to put set screws on the motor caps so I
 can get rid of the
 > bubbles more
 easily.
 > 3) An easy way to add
 > buoyancySnoopy's buoyancy is adjusted
 by
 > placing trawl floats in PVC tubes.
 On one occasion, the
 > oncoming
 passenger's weight required the addition of
 > just one float (i.e. the new guy weighed
 seven pounds more
 > than the one getting
 off). The support diver wasn't
 >
 suited up and the water was 42 degrees, so I just pushed
 a
 > float under the lip of the forward
 MBT. It worked like a
 > charm, and the
 float even stayed in place throughout the tow
 > back to the ramp. Lesson: You can easily
 add a few floats
 > for buoyancy on a
 standard K sub, no special tubes
 >
 required.
 > Most of our dives were along
 a very steep
 > incline, not quite a wall
 but more like a series of ledges
 > and
 very steep slopes. Between the steep terrain and the
 > good visibility, the K250 dome for once
 offered a really
 > good view. We
 typically made our way down the slopes using
 > very slightly negative buoyancy, trailing
 the back corner of
 > a skid on the slope.
 Looking aft, you could see a zigzagging
 >
 trail of silt hanging motionless in the water and tracing
 > our path. The sub compresses with depth,
 so slightly
 > positive buoyancy at the
 surface turned into slightly
 > negative
 at depth, but we're speaking of just a couple
 > of pounds and not anything that caused
 difficulty. In fact
 > at one point we
 stopped dead in the water four or five feet
 > above a flat bottom for about five
 minutes, just waiting for
 > a
 pre-arranged touch-point call on comms. The sub
 didn't
 > rise or sink an inch, she
 just hung there completely
 > immobile for
 five minutes. At about 140 feet the visibility
 > would improve significantly, and the water
 changed from
 > green to blue. It looked
 like ocean instead of lake water.
 >
 I'll post a video, but that'll take a few days to
 > put together. The only
 "incidents" we had were a
 >
 cold bath we took when we closed the hatch over a corner
 of
 > the crew's shirt, and when we
 got hooked on a log at 220
 > feet -
 fortunately reversing got us right off
 >
 it.
 > 
 > Best,
 > Alec 
 > 
 > 
 > 
 > 
 > 
 > -----Inline Attachment Follows-----
 > 
 >
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 > 
 >
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