[PSUBS-MAILIST] Thruster bladders

Sun Sep 19 21:22:50 EDT 2021

Hi Alan
I sent out a request to Jon the other day so will wait to see if he got it.
Thanks for your input and I'll keep ya posted as I go.
Rick

On Sun, Sep 19, 2021 at 12:06 PM Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Rick,
> Jon would be the one to ask about Zoom.
> I am not sure whether he will be providing that or not.
> I won't be going over. I don't know when I could get back to New Zealand
> if I did. You have to book a spot at an isolation facility & pay $3000 for
> the privilege of being locked up for 2 weeks.
> Sounds like you are getting there with the
> Sub.
> If you are now going with air compensation; are you familiar with how to
> modify a second stage regulator for that purpose?
> BTW you can always swap between air & oil compensation by having enough
> hose going up vertical from the thruster that the oil can expand up without
> it being able to turn a bend and come out through the 2nd stage exhaust
> valve.
> Alan
>
>
> On Monday, September 20, 2021, 08:58:04 AM GMT+12, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Alan, that is the most raised question when someone finds out that I am
> building a sub. I honestly don't have a clue as I have never done this
> before except the welding part which is easy for me to estimate as that's
> what i did for a living but when I look ahead on the plans and see an item
> coming up that needs to be done, some things take longer than I thought and
> some things are the opposite. All electrical systems are installed and have
> been checked except I haven't connected all the outside lites to my buck
> boosters, all my internal plumbing is done so once I re chase the threads
> on the flood nipple that is welded in the back dome, I will be ready to
> weld on the back dome and then I think things will pick up a lot faster
> again as I can then attach the back structural framing for the rear MBT,
> fabricate and install the bracket to hold the rear thruster, fab and
> install the steering linkage, mount and plumb both MBT's and finish
> painting the sub and then I can put her on the trailer to find my sweet
> spot for the tongue weight and then put the arm on that comes down over the
> front lifting eye and put my carpeted side guide on so when she comes down
> on the trailer as it is being pulled out, it will be centered, and attach a
> swinging arm that holds the spare tire like Dan Hycroft did,,,,,,,,so, to
> make a long story long, 6 months???🤔
> Are you guys going to the convention or are you going to do it via Zoom? I
> will do Zoom but not sure how it is gonna take place? can you help me with
> that?
> Rick
>
> On Sun, Sep 19, 2021 at 6:02 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Rick. Run it
> Hank
>
> Sent from my iPhone
>
> On Sep 18, 2021, at 3:08 PM, Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> 
> Rick,
> it's going to be fantastic, and you've got a lot of water to explore. I
> have snorkeled off shore from Mauii (Molekino I think it was called) & some
> really great visibility.
> How far off diving do you think you are?
> Alan
>
> On Sunday, September 19, 2021, 08:47:23 AM GMT+12, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> HI Alan
> Good point about using a solvent to get the oil coating off but then
> having an explosion due to the brushes sparking. I also am in a situation
> different than most about the motors getting hot due to the ocean surface
> temperature but I don't see me running them for any length of time while on
> the surface as I will almost always have a mother ship that towes me from
> the ramp to wherever I need to go. I installed a digital temp gauge that
> measures the water so it will be interesting to see what the temp is at
> 350' as well as any noticeable thermal clines. My Brother in law worked at
> a place that sells nothing but gauges and controls so I got it at cost and
> figured what the hell? I did a shore dive with an old friend I used to work
> with offshore and it had been months since I had done that and I just kept
> thinking what it would be like if I were in my sub cruising the coral reefs
> with the fantastic viz and not worrying about an uptake in nitrogen and
> sipping on a Pepsi!
> Rick
>
> On Sat, Sep 18, 2021 at 9:43 AM Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Rick,
> there are lots of pros & cons for running oil
> as apposed to air.
> I wouldn't put any solvent inside the housing in case it dissolves the
> coating on the winding wire, or something like that. And as a motor can
> also work as a generator, if you created a spark by turning the prop,
> perhaps you could blow the thruster to bits if the solvent gasses ignite!
> Some residue oil might be helpful lubricating.
> I am using silicone oil, as marvel mystery oil
> has the potential to harm plastics inside the thruster.
> Oil compensating is better for cooling the motor, which may be
> advantageous travelling on the surface in warm Hawaiian waters.
> The motors coils in a brushed motor rotate in the centre & are not up
> against the housing for direct cooling through the can. Also oil
> compensation gives you a safety aspect (to a degree) if you get any sea
> water in.
> On the negative side, I've heard of thrusters dripping oil on land, with
> the expansion and contraction of the motors & the height of the
> compensating bladder. There is a small power loss. I have heard of people
> adjusting the brushes on their motors to avoid lifting of the brushes due
> to centrifugal force on the oil. (more of a problem on smaller motors)
> Carbon from the brushes can blacken the oil & so it needs to be changed.
> Air compensation is as you say, cleaner. You can see a leak. I spoke with
> the guys that sell the semi-dry Fugu sub, and they prefer air compensation
> saying that if they see an air leak they don't mind, as it is a sign the
> system is working. They were mainly operating in fresh water though!
> The minn kotas are designed to work on boats in surface water with no oil
> in them so no harm in doing that.
> Alan
>
>
>
> On Sunday, September 19, 2021, 06:12:45 AM GMT+12, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Thank's Hank and Allen for your explanations. This would maybe be a good
> topic for someone to go over in detail on a chalkboard at one of our
> conventions if there are others out there that are having the same problem
> wrapping their heads around this type of system?
> Here's another question for ya..... based on these recent discussions and
> the messes I have made on my shop floor, table and myself, I think I have
> decided to go with no oil at all and just go with air, but, I have already
> filled one thruster with the Marvel Mystery Oil and then drained it all out
> but everything inside still has a coating of the oil on it so should I put
> a small amount of a solvent inside the oil fill hole and slosh it around to
> try and get the small amount of oil that is left inside the housing out and
> if so, what would be safe to use without harming the coating that is on the
> copper windings or, is it OK to just leave what small amount of oil that is
> in there and run it now just on air?
> Rick
>
>
> On Fri, Sep 17, 2021 at 2:01 PM Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Rick,
> Just a further explanation as to why you don't need all the air out of the
> thruster....
> If the thruster was 1/4 full of air, and you had a large external bladder
> full of oil attached; if you descended to 300ft, the air in the motor would
> be compressed to 1/12 th its original volume and just be replaced by oil
> from the flexible bladder. The bladder, oil and air in the thruster &
> surrounding water will all be the same pressure.
> When people used to wrap a tube around the thruster and attach it to two
> nipples, there was very little volume in the tube to compensate for the air
> compressing, & so it was critical to get every bit of air out.
> Alan
>
> On Saturday, September 18, 2021, 05:45:19 AM GMT+12, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hank, I forgot your thrusters don't rotate like mine. I assume you are
> talking about the Id of the hose being damaged as it collapses if the
> bubble was at the end? I am still having a hard time wrapping my head
> around having any air in the system as I would think that when the external
> pressure increases as you descend, the extra pressure would be pushing on
> everything evenly and the only things that are weak enough to give are the
> bubble in a bladder or hose and the extra pressure trying to squeeze the
> bubble going past the two factory shaft O rings?
> Rick
>
> On Thu, Sep 16, 2021 at 11:33 PM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Rick, my rubber lines are currently flapping in the breeze sitting on
> top of my drop weight.  Just tie them up, with an arc in the hose, so the
> bubble is in the middle.  This way when the hose collapses it is in the
> middle, not at the end where it could be damaged by the edge of the plug.
> Or taper the plug.   In my opinion, an air bubble is good in a hose.
> If you have a soft bladder, you can work to get rid of every bubble of air
> if you want because the bladder will expand and contract as needed.
> I see no point to worry about it, particularly with the bladder because
> the bubble will simple squeeze to nothing at the highest point of the
> bladder.
> I am trying to think of a reason why an air bubble outside the motor is a
> problem.  Maybe I am missing something.  If I were in salt water with
> expensive motors, i would try to have a small soft bladder.  I like the
> squeeze ball for individual locations, and an air bag for central location
> with multiple motors on it.
> I won't be travelling this fall other than local lakes.
> Hank
>
> On Thursday, September 16, 2021, 11:31:26 AM MDT, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi Hank
> would love a picture. Do you tie the 1' of vacuum hose to the housing so
> it's not flopping in the breeze? I thought I had heard conflicting ideas
> about, "make sure you get all the air out of the thruster and bladder" and
> others saying that they have a little air left in the bladder to allow for
> the hot oil expansion so I am confused. My thinking (which is limited) is
> that you can't have any air in anything because as you know, you can't
> compress a liquid so any air would compress and push out the factory "0"
> rings?
> Shoot me a picture if it's not too much trouble. Need to wrap my head
> around this better so I can pick a method and go for it.
> Are you going to the reunion?
> Rick
>
> On Thu, Sep 16, 2021 at 2:27 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Rick, the vacuum tube is about a foot long and comes out a threaded
> fitting in the housing.  You can drill and tap either end in most cases.
> Choose the location well to make sure the fitting does not interfere with
> the bolts etc.  I have a youtube video on how to do this.
> I can email you a picture of the motor with the hose.  It is still a good
> idea to have a bladder, just be sure it is real soft.
> Hank
>
> On Wednesday, September 15, 2021, 03:17:00 PM MDT, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi Hank.
> Do you happen to have a good picture of your set up? Not clear what you
> are saying. How long is your vacuum tube and I assume it comes out of the
> can but not back in? I woldn't think a rubber hose could inflate enough to
> allow the heated oil to expand it enough before pushing out the two factory
> "0" rings?
> Rick
>
> On Wed, Sep 15, 2021 at 3:31 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Rick.  I have oil filled at the moment because they jettison.  I use a
> length of vacuum hose from a car engine because it is soft.  I intended to
> install a car suspension air bag and connect all the motors to that.   I
> don’t worry much about an air bubble because it will just compress to
> nothing.
>
> Sent from my iPhone
>
> On Sep 15, 2021, at 7:18 AM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> 
> Hi Rick,
>
> You'll find people here who love oil compensation, and others who love
> air. They both work, so I guess it's just a matter of what has worked for
> each person.
>
> I used oil initially. The method was to put two 90 degree nipples in the
> motor can, and attach about a foot of plastic hose to them. To fill, you
> disconnect the top nipple and add oil through the hose until it comes out
> the top nipple. The hose wraps around the can and with that extra length is
> supposed to act as a bladder. I found it worked, but only until I started
> diving my K250 to 250 feet. Then, I was getting internal build-up of
> pressure in the motors. In the end, I figured what was going on was that
> the compression of the hose was insufficient for the thermal contraction
> between the surface, where I'd filled the motors, and the very cold ambient
> temperature at 250 feet. At depth, water was forcing its way past the shaft
> seals, and then the seals would keep the motors pressurized as I rose. My
> solution was to go to a larger bladder, namely this:
>
>
> https://www.google.com/search?q=squeeze+bottles&rlz=1C1CHBF_enUS807US807&sxsrf=AOaemvLRC6ixUOHC7wIDhQcAL78ShVP-Sw:1631711091091&source=univ&tbm=shop&tbo=u&sa=X&ved=2ahUKEwig_9a_hYHzAhUgF1kFHRK2AW0Q1TV6BQgBEKkC&biw=1536&bih=664#spd=4605806885737196691
>
> That said, the larger bladder was something I implemented just before
> selling that sub, so never got to dive it. It was also always a problem
> getting every last bubble out. I'd spend ages doing that, then come back
> the next day and find a bubble in the hose. I was never able to solve that
> issue, and I think the only way would have been to assemble the motor in a
> bucket of oil. The other problem was that if there was an issue, such as
> the over-pressurization one above, my sub created an oil slick. That is NOT
> good, and can attract the wrong sort of attention even if you were to
> use an oil that is harmless.
>
> Now I use air compensation. So far, so good. On my first dive with the
> mechanical arm, I noticed bubbles coming from a hose when I extended the
> arm. The bubbles would cease when I retracted the arm. Closer examination
> showed a nick in the hose, which got pinched closed when the arm was
> retracted. The beauty of air is that if there's a leak, you can see and
> trace it immediately. With oil, I'd have had a small slick but no idea
> where it was coming from. Also, it worked well in the sense that no water
> entered the arm. I have a shutoff valve, so that a leak won't drain the
> sub's air supply, or another way would be to supply the air comp with a
> small independent cylinder.
>
>
> Best,
> Alec
>
> On Wed, Sep 15, 2021 at 12:13 AM Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> I am re thinking what to use for my oil expansion bladder. Would love to
> hear from everyone who chose to go with an oil filled thrusters on what
> they used and how they liked it. I remember someone saying that they used a
> squeeze ball gas tank primer which I like because it is small but I just
> spoke with someone who didn’t use a bladder and had never had a problem.
> Rick
>
> Sent from my iPhone
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