<div dir="ltr">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? <div>
<br></div><div>Thanks,</div><div><br>Alec</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Aug 30, 2014 at 9:22 AM, via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div style="FONT-SIZE:10pt;FONT-FAMILY:Arial;COLOR:#000000"><font color="#000000" face="Arial">
<div>Hank,</div>
<div> </div>
<div>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.</div>
<div> </div>
<div>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.</div>
<div> </div>
<div>Jim</div><div><div class="h5">
<div> </div>
<div>
<div>In a message dated 8/30/2014 5:51:09 A.M. Central Daylight Time,
<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a> writes:</div>
<blockquote style="PADDING-LEFT:5px;MARGIN-LEFT:5px;BORDER-LEFT:blue 2px solid"><font style="BACKGROUND-COLOR:transparent" color="#000000" face="Arial">Brian,<br>Yes, I have heard others have had good success with
different oils. Maybe the rpm drop is less with other oils.
<br>Hank<br>--------------------------------------------<br>On Fri, 8/29/14,
Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>>
wrote:<br><br>Subject: Re: [PSUBS-MAILIST] rpm<br>To: "Personal Submersibles
General Discussion" <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br>Received:
Friday, August 29, 2014, 11:26 PM<br><br>Hank, There is a very thin
mineral<br>oil that might be better that the wd 40<br><br>Brian<br><br>---
<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a><br>wrote:<br><br>From: hank pronk via
Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br>To: Personal
Submersibles General Discussion
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br>Subject: Re: [PSUBS-MAILIST]
rpm<br>Date: Fri, 29 Aug 2014 13:23:31 -0700<br><br>Vance,<br>Yes for sure,
Gamma has two separate amp gauges, one for the<br>motor and one for the rest
of the sub. All 24v and the<br>trolling motor is 12 v<br>Hank
<br>--------------------------------------------<br>On Fri, 8/29/14, via
Personal_Submersibles
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br>wrote:<br><br> Subject: Re:
[PSUBS-MAILIST] rpm<br> To: <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a><br>
Received: Friday, August 29, 2014, 4:03 PM<br> <br> Yeah,
too<br> simple. Maybe that's a good guess, but..... I will say<br>
that an ammeter in the boat is a good thing. You can keep<br>an<br> eye
on things, and if it goes UP at some stage, you would<br> suspect a
thruster issue (a tangle, or a bearing failure<br>or<br> whatever). All
it takes is an appropriate shunt and a<br>gauge<br> (in my pre-digital
steampunk mind). Okay, thanks anyway. I<br> was curious, that's
all.<br> Vance<br> <br> <br> <br> <br>
<br> <br> -----Original<br> Message-----<br>
<br> From: hank pronk via Personal_Submersibles<br>
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br> <br> To: Personal
Submersibles General Discussion<br>
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br> <br> Sent: Fri, Aug
29, 2014 3:56 pm<br> <br> Subject: Re: [PSUBS-MAILIST]
rpm<br> <br> <br> <br> <br> <br>
<br> <br> <br> <br> Vance,<br> I did not do an
amp draw test because I do not have the<br> technology in house. I
<br> would guess with a 10% rpm drop, there may be a 10% amp<br>
increase. That would be <br> to simple :-)<br> <br>
Hank<br> --------------------------------------------<br> On Fri,
8/29/14, via Personal_Submersibles
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br> <br> wrote:<br>
<br> Subject: Re: [PSUBS-MAILIST] rpm<br> To:
<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a><br> Received: Friday, August 29, 2014,
3:39 PM<br> <br> Hank,<br> Did you check the amperage? I
wonder if the<br> resistance causes a higher draw, and if so,
how<br> much?<br> <br> Vance<br> <br> <br>
<br> <br> <br> <br> -----Original<br>
Message-----<br> <br> From: hank pronk via
Personal_Submersibles<br>
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br> <br> To:
personal_submersibles<br>
<<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br> <br> Sent: Fri, Aug
29, 2014 3:33 pm<br> <br> Subject: [PSUBS-MAILIST] rpm<br>
<br> <br> <br> <br> <br> <br> <br>
<br> <br> I am working on a hydraulic<br> pump that will be
external and pressure compensated <br> in oil. I am using a
trolling motor to drive<br>the pump. A<br> while back there was
<br> a question about rpm drop when a trolling motor
is<br>filled<br> with oil. I bench <br> tested that today,
and the motor runs at 2,000rpm<br>stock and<br> 1,800 rpm full of
<br> WD40.<br> Hank<br>
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