[PSUBS-MAILIST] Motor modification

Sat Dec 10 13:42:44 EST 2016

Hey Alan,

Been tied up for a couple days since this post but thanks for the
heat/expansion/volume data as it makes it much easier to comprehend. Based
on what I see here, is it safe to assume that due to the amount of
expansion of oil, just wrapping the motor several times with the clear PVC
hose and connecting the other end to the second barbed fitting on the motor
would not work due to the fact that the hose would not expand enough to
allow for the volume of expanded oil where as a bladder half filled would
work better?
Also would like to hear from the others out there who have used only the
clear hose to see if they have had any issues with leakage?

Thanks all
Rick

On Wed, Dec 7, 2016 at 1:42 PM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Rick,
> Sean's beat me to it, but I'll add that you can usually look up
> your compensating oil's coefficient of thermal expansion, &
> calculate how much it will be. Engine oil is about .0007. That
> would mean that if you had a liter of oil (1000cc) & the temperature
> went up by 50 degrees C, then the oil would expand another 35cc.
> Not a lot given  that you would not require a lot of oil in the thruster.
> Getting the air out could be a bigger problem & it would expand more.
> In a declassified military document on compensating I read , it talks
> about & demonstrates how to pull a vacuum on a thruster to get all
> the air out.
> Another issue that I mentioned earlier is that all seals leak oil to
> lubricate themselves, so having a reservoir makes sense.
> What I am doing is enclosing my motor wiring in a hose & filling
> the motor & hose with oil. In to this I will have a T to a relieving
> regulator
> (PR 364) that will pressurize the system with air at 4psi above ambient.
> Carsten & Emile had all sorts of problems about oil expanding & leaking
> then contracting & sucking in water. Will re post their emails if I
> can find them.
> Regards Alan
>
>
> ------------------------------
> *From:* Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Thursday, December 8, 2016 10:38 AM
> *Subject:* Re: [PSUBS-MAILIST] Motor modification
>
> Alan,
>
> I am embarrassed to say that I am still not getting this concept. You
> mentioned in your email about the clear hose that people wrap around there
> Minn-Kota motors and mention about collapse pressure and also mention about
> lighting systems. Maybe we are talking about two separate things?
> My question was based on wondering about that same clear tubing that wraps
> around the motor pods to allow for when the oil gets hot from use and
> expands.
> Taking any air out of the equation, I got the impression that you could
> completely fill a motor with dielectric oil (or any liquid for that matter)
> and then take it to any depth and since you basically can't compress a
> liquid, there would be no water ingress to the motor (except for the small
> space between the two prop shaft 0 rings.) So now when you add a slight
> internal increase in pressure from the oil being heated from use, people
> use the clear tubing that wraps around the outside of the motor (which is
> also 100% filled with the same oil) as a place for the oil to go to expand
> rather that spitting out the prop shaft 0 rings. Am I correct so far?
> So my question was, the clear hose wall must be flexible enough to allow
> for expansion before placing enough pressure on the prop shaft 0 ring to
> dislodge? And then if you don't get all the air out of the motor or clear
> hose or bladder, don't you have the water pressure trying to compress that
> bubble from not only the bladder or tube but past the shaft 0 ring as well?
>
> Rick
>
>
> On Mon, Dec 5, 2016 at 11:03 AM, Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Some compensating thoughts.
> On James Cameron's sub they used IV drip bags. I am not sure what they
> were compensating.
> These come with various means of hose attachment.
>    With regard to the wrap around hose method; I did some calculations on
> a standard pvc hose, & surprisingly
> the colapse pressure was around 100psi. I am sure one of Nuytco's
> technicians told me they crimped the hose
> that was compensating their lights, to initiate the collapse of the hose
> for compensation.
>    The industry standard for thrusters seems to be around 4psi internal
> overpressure,
> but the compensators they use for this are relatively expensive. Hugh came
> up with
> the novel idea of using a releiving regulator set at 4psi (Parker PR364).
> Cliff is using this.
> This could be used for air or oil compensation.
>    The seals need oil for lubrication, & I have read that they can use
> about a teaspoon a day. Based
> on that I would have some sort of reservoir.
>    Depending on the motor it may be tricky to get all the air out. If you
> have a bearing in a bore
> followed by a seal, the air / oil would have to move through the bearing
> which may be a sealed type
> or packed with grease. The Minn kotta diagrams I have seen show 2 seals;
> so how do you get oil or
> ambient pressure between those? One will fail when you exceed it's
> pressure limit.
> Alan
>
>
> ------------------------------
> *From:* James Frankland 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:* Tuesday, December 6, 2016 4:44 AM
> *Subject:* Re: [PSUBS-MAILIST] Motor modification
>
> Hi Antoine\Hank.
>
> Thanks guys.  drinking bladder looks good.  I was thinking of a furniture
> lift bag, which is very similar.  I use a hot water bottle for the aft
> motor.
>
> Hank, what do you use for a bladder?
>
> Thanks
> James
>
> On 5 December 2016 at 13:18, hank pronk via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> James,
> I put my fill plug under the prop, in the flat end cap,  and it works like
> a dream.
> Hank
>
>
> On Monday, December 5, 2016 5:37 AM, Antoine Delafargue via
> Personal_Submersibles <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>> wrote:
>
>
> Hi frank
> I have done something like that for my prop shaft seal oil filled
> compartment.  But first i removed the hose and filled with a serynge with
> long steel needle. Then put the tube and filled it with the serynge.
> The tube is flexible and transparent, from endurance sport
> platypus drinking bladder
> Works well
> Regards
> Antoine
> On Monday, December 5, 2016, James Frankland via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Hi All
>
> I have been talking to Rick about motor compensation which has got me
> thinking.
>
> I originally did my motors like other psubbers have done with the rubber
> tubes around the sides, but have found them a real pain to fill.  Problem
> is the location of the tube, plus the tiny bit of protruding pipe nipple on
> the inside.
>
> So, I modified the motors by drilling a hole in the top part of the
> aluminium endcap and use that now as the vent\final fill.  Its better, but
> still awkward.
>
> I have suggested to Rick this idea, which I am tempted to adopt myself.
> Blocking off the existing side mounted pipe nipples and
> filling\venting\compensating all from the one top hole.  There would be a
> rubber bulb of some sort on the end of the pipe.  2x pictures show filling
> and operation.  Appologies for rubbish drawings, im at work.
>
> What does everyone think?
>
>
> 
> 
>
>
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