[PSUBS-MAILIST] Motor modification

Wed Dec 7 22:03:45 EST 2016

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! pacity in
> 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 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 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.org>
>>> *To:* Personal Submersibles General Discussion <
>>> 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> 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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