[PSUBS-MAILIST] Dive report: Snoopy at Seneca

Sat Jun 6 21:32:35 EDT 2015

Also tuned inductors will help disipate the spikes caused by the controlers.

Keith T

Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

>Thanks Ken,I was nearly going to ask you to comment in my post.Is there an alternative to capacitors or to the electrolitic capacitors usually used?I was looking at this option.http://www.dialelectrolux.ru/files/file/electronicon/e61-data-charts-engl-deut.pdf
>Alan
>      From: Ken Martindale via Personal_Submersibles <personal_submersibles at psubs.org>
> To: 'Personal Submersibles General Discussion' <personal_submersibles at psubs.org> 
> Sent: Sunday, June 7, 2015 12:19 PM
> Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca
>   
>#yiv9053454032 #yiv9053454032 -- _filtered #yiv9053454032 {font-family:Helvetica;panose-1:2 11 6 4 2 2 2 2 2 4;} _filtered #yiv9053454032 {panose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv9053454032 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;} _filtered #yiv9053454032 {font-family:Georgia;panose-1:2 4 5 2 5 4 5 2 3 3;}#yiv9053454032 #yiv9053454032 p.yiv9053454032MsoNormal, #yiv9053454032 li.yiv9053454032MsoNormal, #yiv9053454032 div.yiv9053454032MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:12.0pt;}#yiv9053454032 a:link, #yiv9053454032 span.yiv9053454032MsoHyperlink {color:blue;text-decoration:underline;}#yiv9053454032 a:visited, #yiv9053454032 span.yiv9053454032MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv9053454032 span.yiv9053454032link-enhancr-element {}#yiv9053454032 span.yiv9053454032link-enhancr-view-on-domain {}#yiv9053454032 span.yiv9053454032EmailStyle19 {color:#1F497D;}#yiv9053454032 .yiv9053454032MsoChpDefault {font-size:10.0pt;} _filtered #yiv9053454032 {margin:1.0in 1.0in 1.0in 1.0in;}#yiv9053454032 div.yiv9053454032WordSection1 {}#yiv9053454032 Adding extra capacitors helps reduce the magnitude of the inductive voltage spikes.  Ken Martindale.  
>
>From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Alan James via Personal_Submersibles
>Sent: Saturday, June 06, 2015 6:48 PM
>To: Personal Submersibles General Discussion
>Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca  Thanks for the report Alec, great stuff.re the motor controllers; I've been reading a bit about inductance in long wire runs from battery tomotor controllers, that harms the capacitors on the controllers.This could be a problem that is unique to our submarines & not an issue with things like golf carts& wheel chairs.My reading has been mainly about BLDC motor controllers but asume PWM controllers for brushedmotors would be similar. Because of the rapid switching on & off of the power to the motor, there is acurrent surge hitting the capacitors & the longer the wire run, the more the power in the surge.A water analogy would be turning a valve off suddenly as washing machines do, sometimes witha "thunk" sound & a rattle of the pipes.Hugh mentioned he had problems with his Curtis BLDC motor controllers.Attached is the problem & solution, which is to put capacitors in parrallel along the battery wire; however there must be a better way.Regards Alantoo long battery wires will kill ESC over time: precautions, solutions & workarounds - RC Groups
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>      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
>Sent: Sunday, June 7, 2015 12:20 AM
>Subject: Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca
>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 
>
>
>
>
>
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