[PSUBS-MAILIST] Oil Compensator

Thu Apr 6 11:49:29 EDT 2017

OK, looking forward to seeing them.

Cliff

On Thu, Apr 6, 2017 at 10:41 AM, james cottrell via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Cliff!
>
> This is Greg Cottrell (my first name is James)
> I don't have any pictures of that set up. The sub had air comp from about
> 1994 to about 1998. I'm going to set it up again very soon and I'll be sure
> to take pics this time.
>
> Greg
>
> ------------------------------
> *From:* Cliff Redus via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Thursday, April 6, 2017 9:21 AM
> *Subject:* Re: [PSUBS-MAILIST] Oil Compensator
>
> James, this is an interesting approach using the scuba second stage demand
> regulator for pressure compensation.  Do you have any pictures of the
> setup?
>
> Cliff
>
> On Wed, Apr 5, 2017 at 10:54 PM, james cottrell via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
> Alan/ Cliff,
>
> That's interesting- but I don't understand why it's better than a good
> working second stage? This is what I did-
>
> Three trolling motors (one vertical and port/starboard pushers) had clear
> vinyl tubing connected to the tube/pipe where the wires come out.
> Each clear piece of tubing ran to the "inlet" side of a small water filter
> housing (the kind with a clear plastic removable sight glass).
> The water filter housing served as a junction box so each motor could be
> removed individually.
> The tubing them came out of the "outlet" side of the filter housing and
> went to a "T" fitting.
> One piece of tubing carrying the wires went from the "T" to a penetrator
> in the hull.
> The other piece of tubing went downward to a set of two "T" fittings that
> served as a manifold connecting all 3 pieces of tubing together.
> Finally one Large piece of tubing went to a scuba second stage mounted low
> on the hull (connected where the mouthpiece usually goes).
>
> When the sub descended, air was "inhaled" into the motors. When the sub
> ascended, the air in the motors "Exhaled" back out of the reg. Very simple.
>
> The only reason I went to oil was that it seemed to be all the rage at
> that time.  Having used both methods, I have to say that I like the air
> better. It was easy to set up and take apart without a lot of mess and best
> of all- no worries about a leak.
>
> Greg C
>
> ------------------------------
> *From:* Alan via Personal_Submersibles <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>>
> *To:* Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *Sent:* Wednesday, April 5, 2017 8:58 PM
> *Subject:* Re: [PSUBS-MAILIST] Oil Compensator
>
> Greg,
> Cliff's regulator is not a divers second stage reg. It runs direct from
> the first stage
> & you can dial in the overpressure you require. The excess pressure above
> set
> pressure escapes through the handle of the regulator but only in the
> "relieving" model.
> They go for around $150-
> I contacted the guys from Fugu sub a few years ago. http://www.fugusub.com/
> fugusub.html <http://www.fugusub.com/fugusub.html>
> about compensating, am pretty sure they use Minn  Kotas. They preferred
> air
> compensation. They operate out of Florida, so warm shallow waters.
> Alan
>
> Sent from my iPad
>
> On 6/04/2017, at 12:24 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Cliff,
> What is the cost for a air compensated set up?
> Hank
>
>
> On Wednesday, April 5, 2017 6:12 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
>
> Steve,
> Yes I need a bushing (bearing) that holds the prop shaft in the water.  It
> would be like a cutlass prop shat bearing on a boat.
> It would have to be long enough to hold the prop strait and true.  Also it
> would need to act as a thrust bearing.
> Hank
>
>
> On Wednesday, April 5, 2017 6:00 PM, Stephen Fordyce via
> Personal_Submersibles <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>> wrote:
>
>
> Hi Hank,
> By "finding a bushing for the propeller shaft that is lubricated by the
> water" do you mean the bearings which will sit outside the pressure housing?
>
> I started looking into ceramic bearings for just this application, and
> they were interesting - ie. some of them have no metal parts and little
> need for lubrication.
>
> Cheers,
> Steve
>
> On Thu, Apr 6, 2017 at 9:47 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Sean,
> I think one of us should develop a magnetic coupler in kit form.  Maybe
> if there is an interest with potential sales it could become a reality.  I
> have come close to starting and even bought the magnets.  My stumbling
> block is finding a bushing for the propeller shaft that is lubricated by
> the water.
> Hank
>
>
> On Wednesday, April 5, 2017 5:29 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
>
> I've decided to go with the   PSF - 20 cSt Silicone Bath Fluid for my
> motors.
>
> http://www.clearcoproducts. com/pure-silicone-low- viscosity.html
> <http://www.clearcoproducts.com/pure-silicone-low-viscosity.html>
>
>
> Brian
>
> --- personal_submersibles at psubs. org <personal_submersibles at psubs.org>
> wrote:
>
> From: Alan James via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> Subject: Re: [PSUBS-MAILIST] Oil Compensator
> Date: Wed, 5 Apr 2017 22:48:50 +0000 (UTC)
>
> Jon,
> I don't know whether you have followed, but I have made a brushless 2000W
> thruster
> which I trialed in a pool for 30 hrs. The glue on the hall sensor board
> melted
> & it stopped because the timing went out. Apparently the glue was designed
> to melt
> so people could adjust the timing. The thruster got hot because the
> compensating oil
> was being forced away from the motor through centrifugal force, & up the
> wiring tube.
> If I had an overpressure on the system I could have prevented this, but
> didn't think it
> was needed in a few feet of water. I was running this motor with 2 lip
> seals with ambient
> pressure in between, but have purchased a mechanical seal for the next
> version.
>    It had a comparable or better thrust to Watt ratio than a lot of the
> advertised ratings
> of commercial thrusters.
>    I think it is a matter of time before Minn kota put out a brushless
> thruster if they haven't
> yet. Most of the commercial ROV & submarine thrusters are now brushless.
>    If there was enough room to fit a mechanical seal on a Minn kota it
> would be a big
> improvement. The white paper suggests grinding the Minn kota shaft to a
> specific
> finish, with matching bearing & seal, however a mechanical seal is more
> tolerant of
> the shaft surface finish & you could avoid this.
>    Re the heat; one concern is transferring heat off the windings, which
> oil compensating
> will do 100 times better than air. However Minn kota motors would have
> large gauge windings
> that can cope with the heat.
> Below is a 2010 thread by Carsten dealing with expansion.
> Alan
>
> Alan and the other gentlemens,
>
> our expierence with oil filled motors, batterys or even propeller shafts is that the oil expand if the motor is runing longer time.
> Simple because its warm up. We had that problem on Eurosub on the first dives.
> And on Euronaut we filled the bladder complet up and the get pretty hard in the hot summer just by sun heating the sub.
> A full filled bladder with over pressure creates a lot of interal
> pressure in the wrong direct - a lot of force for the bladder itself and hose work.
>
> Therefore our bladder are only half expand during the filling. But still free of any air.
> An other point is that the bladder has to be not to small.
>
> To create a slightly overpressure on the motorseal you just install the bladder below the motorcasing.
> But we found out that on trolling motor (electric outboards) this is not nessesary. There seals are good for some
> douzend feets at least - so you can install the bladder else were.
> Filling is simpler if the bladder is slightly over the motor - you can vent the system direct on the filling point.
>
> Another point is that we install now one bladder per motor  - in the earlier sub (Sgt.Peppers) we install a central
> one for all motors. Hard to find a leak after a dive with all the T-crossing piepings and motorseals..
>
> vbr Carsten
>
>
>
>
>
>
> ------------------------------
> *From:* Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *To:* Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *Sent:* Thursday, April 6, 2017 8:31 AM
> *Subject:* Re: [PSUBS-MAILIST] Oil Compensator
>
> Hi Alan,
>
> Yeah, that white paper pretty much just states fill it with oil and you're
> good to go.  It doesn't address some of the issues that have come up on the
> list regarding heat and expansion, inter-seal cavity, etc.  I understand
> the drive to find a perfect solution and that minn-kota oil compensation is
> not perfect, I'm just trying to understand the real-world ramifications of
> using it as that white paper suggests and most psubbers have implemented.
> Given that water is such a good heat sink, are the heat and expansion
> issues of the oil really that serious?  I know Alec wrote something about
> his experience with this some time ago but am having a hard time finding
> that thread.  Pretty sure SNOOPY is still using simple oil compensation
> regardless.
>
> Jon
>
>
> On 4/5/2017 4:02 PM, Alan James via Personal_Submersibles wrote:
>
> Jon,
> Cliff has been doing a lot of work on Minn kota modifications & has the
> hands
> on experience. If he's not tuning in it would be worth contacting him
> privately.
> The Minn-kota seal set up is not ideal, with the gap between the two seals
> meaning one or the other seals will fail when their pressure rating is
> exceeded.
> The outer seal seems to serve a double purpose, being the first line of
> defense
> against water ingress & also a sacrificial seal that will see all the
> abrasive muck stirred up by the prop.
> Noticed in this kit that the outer seal has a shield to protect it.
> Historically in deep diving set ups they have had dual seals, but with
> either ambient pressure between them,
> or a cascaded pressure system, and normally mechanical seals. The outer
> seal was regarded as sacrificial.
>    Maybe you could pack between the seals with grease to reduce the air
> gap.
> I am not sure whether you could simply reverse the inner seal or not as
> they need a shoulder that the pressure
> will push them up against.
> Cliff is using a small relieving air regulator to compensate his motors.
> The regulator is fed air from your tanks
> & is set at an overpressure of about 4psi. The regulator is orientated
> upside down as the relieving air feeds
> out through the handle portion & the orientation will stop water entering
> when this valve opens.
> This system was suggested by Hugh, & Cliff is trialing it. It has the
> advantage that you could either air or oil
> compensate. If your motor ran out of oil it would just be replaced with
> air above ambient pressure.
> I am not sure at what pressure the relieving valve opens.
>    There is this very good Psub resource from an expert in modifying Minn
> kotas for underwater use.
>
>
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