[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Fri Jun 5 22:18:47 EDT 2015

FWIW, my boat is available for any surface support for deep tests and I can also provide guidance to local wrecks in Seneca if anyone else is interested.
I also have a scuba compressor for air fills.

Al Secor

--------------------------------------------
On Fri, 6/5/15, swaters at waters-ks.com 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>
 Date: Friday, June 5, 2015, 9:20 PM

 Alec,So
 cool. I wish I could of made it! Can't wait to see the
 video.Thanks,Scott
 Waters

 Sent from my U.S.
 Cellular® Smartphone

 -------- Original message
 --------
 From: Alec Smyth via
 Personal_Submersibles
 <personal_submersibles at psubs.org> 
 Date:06/05/2015  5:16 PM  (GMT-06:00) 
 To: Personal Submersibles General Discussion
 <personal_submersibles at psubs.org> 
 Cc:

 Subject: [PSUBS-MAILIST] Dive report:
 Snoopy at Seneca 

 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 

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