[PSUBS-MAILIST] Minn Kotta 101 - Thruster Reliability

Sat Jul 29 09:52:20 EDT 2023

 John, I think mineral oil might work.  See page III-11, section 3.5 in  "
https://apps.dtic.mil/sti/citations/AD0894795
 I don't know anything about these thruster  motors but this oil is a petroleum base, red, hydraulic oil that is essentially mineral oil.  See https://petroleumservicecompany.com/blog/what-is-mil-h-5606/ for more info on MIL-H-5606.  It has a kinematic viscosity of 13.8 cs at 100 F and 0 psig. More than likely this is brushless motor with the brush arcing issues that we are seeing not relevant.
Cliff

    On Friday, July 28, 2023 at 10:02:26 PM CDT, John Bussard via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 While a little out of my depth on technical specs here-
A good friend and coworker here in San Diego has been an interesting person to discuss my “new hobby” with: He briefly worked as an electronic technician on ROVs with the Navy Deep Submergence Unit here, around the turn of this century.
When I told him about this discussion, his memory was that their oil compensation was done with plain old mineral oil.
Unsure if it’s worth considering but thought I’d share that historical context.
John

Sent from my iPhone

On Jul 28, 2023, at 19:46, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Cliff,I don't think brushed motors are the way to go.The brushes can contaminate the oil & lift due to the centrifugal force of the oil. And they are less efficient than brushless motors. Also the 101s have that double o-ring seal system, that means one of the o-rings will fail when over 30ft or so.A descent brushless option with a ceramic mechanical seal and silicone compensation would be a big improvement.I bought some of the Shell Morlina some years ago.  An industrial chemist advised me it was low in aromatics and less likely to dissolve plastics than other options. I believe it was used to lubricate high speed spindles etc.It still had an effect on plastics.Alan 
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  On Sat, 29 Jul 2023 at 12:42 pm, Cliff Redus via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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