[PSUBS-MAILIST] Motor modification

Thu Dec 8 01:38:17 EST 2016

That's OK Rick,we will organize a Psub conference in Hawaii based around your submarine,when you have it perfected! :)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 4:03 PM
 Subject: Re: [PSUBS-MAILIST] Motor modification

Thanks Alan and Sean for bearing with me on this and re stating it so it made sense. I just want to make sure I get it rite the first time if possible!
Rick 
On Wed, Dec 7, 2016 at 12:11 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Rick - if all you have is the tube (i.e. no separate bladder), then if you fill it completely, any additional oil has no place to go unless the tube wall stretches. Similarly, most tubes with any rigidity at all resist collapse due to external pressure, so if you have an air bubble within the housing that shrinks and demands compensation oil, the tube won't necessarily deliver it unless it is able to collapse - meaning either it has to be flimsy, or you have to crimp or bend it in order to initiate the collapse, so that the collapse can propagate down the remainder of the tube length in order to lose volume.  Ideally, your compensation reservoir is filled to an intermediate volume that can either accept or deliver oil as demanded.  Keep in mind that as your motor heats up, the oil will heat up and expand, but then the housing will heat up and increase volume, drawing back some of that oil. A good compensation system has some ca! pacityin both directions. The comment about lights was that wiring can be run through oil filled tubes in order to pressure compensate the light housings, but this can suffer from the same problem - clear PVC tubing is a lot stronger than you might think, and you need to help it along with a crimp, otherwise external pressure may stress the tubing but not actually compress it. Personally, I am a fan of rigid plumbing to a remote non rigid oil reservoir (which may be pressure biased or not, depending on the application), but I know that doesn't work for everybody.  Bubbles aren't a huge deal, as long as you have enough compensation oil available to accommodate the volume change due to pressure. Obviously you should vent as much air as you can out of the system.Sean

On December 7, 2016 2:38:16 PM MST, Rick Patton via Personal_Submersibles <personal_submersibles at psubs. org> wrote:
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 theoutside 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 t! he 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.o rg>
 To:Personal Submersibles General Discussion <personal_submersibles at psubs.o rg> 
 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 aftmotor. Hank, what do you use for a bladder? ThanksJames  
On 5 December 2016 at 13:18, hank pronk via Personal_Submersibles <personal_submersibles at psubs.o rg> 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> wrote:

 Hi frankI 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 steelneedle. Then put the tube and filled it with the serynge. The tube is flexible and transparent, from endurance sport platypus drinking bladder
Works wellRegards Antoine 
On Monday, December 5, 2016, James Frankland via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

Hi All I have been talking to ! Rickabout 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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