[PSUBS-MAILIST] rpm

Sat Aug 30 10:36:22 EDT 2014

That's an interesting test Hank. and I wonder whether someone with more
motor knowledge than I could infer an efficiency figure from the speed
reduction. It's tempting to say 10%, but I imagine that would be
simplistic, assuming the test was in an unloaded condition. Do you have any
way of running the same test in a tub or with the thruster immersed, and
measuring the currents?

Thanks,

Alec

On Sat, Aug 30, 2014 at 9:22 AM, via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>  Hank,
>
> I don't know if you will find an oil with lower viscosity than WD40.  The
> problem with WD40 is that it is a solvent that damages plastic and rubber
> components within the motor.  Alec Smyth did a lot of testing on various
> oils.  The last I knew the medium of choice was Marvel Mystery Oil.  It's
> safe for the seals, etc., and has a lower viscosity than any straight
> mineral oil.
>
> For thrusters, comparative amp draw at a given RPM (with associated heat
> build-up) is probably more significant than drop in maximum RPM since we're
> not generally operating at maximum.  That might not be true when you're
> using the motor to operate a pump.
>
> Jim
>
>  In a message dated 8/30/2014 5:51:09 A.M. Central Daylight Time,
> personal_submersibles at psubs.org writes:
>
> Brian,
> Yes, I have heard others have had good success with different oils.  Maybe
> the rpm drop is less with other oils.
> Hank
> --------------------------------------------
> On Fri, 8/29/14, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Subject: Re: [PSUBS-MAILIST] rpm
> To: "Personal Submersibles General Discussion" <
> personal_submersibles at psubs.org>
> Received: Friday, August 29, 2014, 11:26 PM
>
> Hank, There is a very thin mineral
> oil that might be better that the wd 40
>
> Brian
>
> --- personal_submersibles at psubs.org
> wrote:
>
> From: hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] rpm
> Date: Fri, 29 Aug 2014 13:23:31 -0700
>
> Vance,
> Yes for sure, Gamma has two separate amp gauges, one for the
> motor and one for the rest of the sub. All 24v and the
> trolling motor is 12 v
> Hank
> --------------------------------------------
> On Fri, 8/29/14, via Personal_Submersibles <
> personal_submersibles at psubs.org>
> wrote:
>
>   Subject: Re: [PSUBS-MAILIST] rpm
>   To: personal_submersibles at psubs.org
>   Received: Friday, August 29, 2014, 4:03 PM
>
>   Yeah, too
>   simple. Maybe that's a good guess, but..... I will say
>   that an ammeter in the boat is a good thing. You can keep
> an
>   eye on things, and if it goes UP at some stage, you would
>   suspect a thruster issue (a tangle, or a bearing failure
> or
>   whatever). All it takes is an appropriate shunt and a
> gauge
>   (in my pre-digital steampunk mind). Okay, thanks anyway. I
>   was curious, that's all.
>   Vance
>
>
>
>
>
>
>   -----Original
>   Message-----
>
>   From: hank pronk via Personal_Submersibles
>   <personal_submersibles at psubs.org>
>
>   To: Personal Submersibles General Discussion
>   <personal_submersibles at psubs.org>
>
>   Sent: Fri, Aug 29, 2014 3:56 pm
>
>   Subject: Re: [PSUBS-MAILIST] rpm
>
>
>
>
>
>
>
>
>
>   Vance,
>   I did not do an amp draw test because I do not have the
>   technology in house. I
>   would guess with a 10% rpm drop, there may be a 10% amp
>   increase. That would be
>   to simple :-)
>
>   Hank
>   --------------------------------------------
>   On Fri, 8/29/14, via Personal_Submersibles <
> personal_submersibles at psubs.org>
>
>   wrote:
>
>   Subject: Re: [PSUBS-MAILIST] rpm
>   To: personal_submersibles at psubs.org
>   Received: Friday, August 29, 2014, 3:39 PM
>
>   Hank,
>   Did you check the amperage? I wonder if the
>   resistance causes a higher draw, and if so, how
>   much?
>
>   Vance
>
>
>
>
>
>
>   -----Original
>   Message-----
>
>   From: hank pronk via Personal_Submersibles
>   <personal_submersibles at psubs.org>
>
>   To: personal_submersibles
>   <personal_submersibles at psubs.org>
>
>   Sent: Fri, Aug 29, 2014 3:33 pm
>
>   Subject: [PSUBS-MAILIST] rpm
>
>
>
>
>
>
>
>
>
>   I am working on a hydraulic
>   pump that will be external and pressure compensated
>   in oil.  I am using a trolling motor to drive
> the pump.  A
>   while back there was
>   a question about rpm drop when a trolling motor is
> filled
>   with oil.  I bench
>   tested that today, and the motor runs at 2,000rpm
> stock and
>   1,800 rpm full of
>   WD40.
>   Hank
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