<table cellspacing="0" cellpadding="0" border="0"><tr><td valign="top">Pete,<br/><br/>If you pay attention closely, Hank is a reincarnated soul from the Klondike era!<br/><br/>Joe <a href="https://overview.mail.yahoo.com?.src=iOS"><br/><br/>Sent from Yahoo Mail for iPad</a></td></tr></table>            <div id="_origMsg_">
                <div>
                    <br />
                    <div>
                        <div style="font-size:0.9em">
                            <hr size="1">
                            <b>
                                <span style="font-weight:bold">From:</span>
                            </b>
                            hank pronk via Personal_Submersibles <personal_submersibles@psubs.org>;                            <br>
                            <b>
                                <span style="font-weight:bold">To:</span>
                            </b>
                            Personal Submersibles General Discussion <personal_submersibles@psubs.org>;                                                                             <br>
                            <b>
                                <span style="font-weight:bold">Subject:</span>
                            </b>
                            Re: [PSUBS-MAILIST] Minn Kota 101 - thread spec                            <br>
                            <b>
                                <span style="font-weight:bold">Sent:</span>
                            </b>
                            Sat, Jul 26, 2014 10:46:24 PM                            <br>
                        </div>
                            <br>
                            <table cellspacing="0" cellpadding="0" border="0">
                                <tbody>
                                    <tr>
                                        <td valign="top"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"><div><span>Hi Pete,</span></div><div style="color:rgb(0, 0, 0);font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;font-style:normal;background-color:transparent;"><span>I went through all the usual steps to get a magnetic coupler for Gamma.  The cost was in the 2K range for all the parts, two magnet assemblies and a barrier.  I went to my best resource, ebay, and found a brand new surplus hydraulic pump with a magnetic coupler.  Based on the pump specs, port sizes etc, I new the magnetic coupler was sufficient in size for Gamma.  I bought the pump complete for about 200 dollars, amazing!  It was a simple machining job to make it work with Gamma's existing set up.  Magnetic couplers are
 really a great
 set up.  Guess that is why Nuytco uses them.  It would be nice to make a kit to fit the minkota  motors.  A small pump conversion is all it would take. If the end cap were replaced in the kit, I am sure sufficient depths could be achieved with them.</span></div><div style="color:rgb(0, 0, 0);font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;font-style:normal;background-color:transparent;"><span>Hank</span></div> <div class="qtdSeparateBR"><br clear="none"><br clear="none"></div><div class="yahoo_quoted" style="display:block;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"> <div class="yqt8395328103" id="yqt17729"><div dir="ltr"> <font face="Arial" size="2"> On Saturday, July 26, 2014 5:19:05 PM, Jon Eide Pettersen
 via Personal_Submersibles
 <personal_submersibles@psubs.org> wrote:<br clear="none"> </font> </div>  <br clear="none"><br clear="none"> <div class="y_msg_container"><div id="yiv2586516062"><div>Would it be a good idea to use an inert gas like nitrogen or argon instead of air to pressure compensate thrusters? This is because compressed air will have a high partial pressure of oxygen, making the atmosphere in the thrusters more flammable. Also, if there is water trapped inside the thrusters, a high pp of oxygen will greatly speed up the corrosion rate.<br clear="none">
<br clear="none">
The downside is, of course, that air is readily available while an inert gas cost more. <br clear="none">
<br clear="none">
Regards, <br clear="none">
Jon E. Pettersen <br clear="none"><br clear="none"><div class="yiv2586516062yqt4205053554" id="yiv2586516062yqtfd74730"><div class="yiv2586516062gmail_quote">On 26 July 2014 22:27:49 CEST, Pete Niedermayr via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv2586516062gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;padding-left:1ex;border-left-color:rgb(204, 204, 204);border-left-width:1px;border-left-style:solid;">
<pre class="yiv2586516062k9mail"><br clear="none">Hank, What is the story behind your magnetic coupler ? You were talking about them on the list and then you had one. Did you buy it ? If so where? Did you build it ? If so from what plans.<br clear="none"><br clear="none">Thanks Pete<br clear="none"><br clear="none"></pre><div class="hr" style="margin:5px 0px;padding:0px;border:1px solid rgb(204, 204, 204);height:0px;line-height:0;font-size:0px;"></div><br clear="none">On Mon, 7/21/14, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br clear="none"><br clear="none"> Subject: Re: [PSUBS-MAILIST] Minn Kota 101 - thread spec<br clear="none"> To: "Personal Submersibles General Discussion" <personal_submersibles@psubs.org><br clear="none"> Date: Monday, July 21, 2014, 6:20 PM<br clear="none"> <br clear="none"> there is a very nice<br clear="none">
 solution here.  Magnetic couplers, it wouldn't take<br clear="none"> much to convert a minkota  to a magnetic coupled<br clear="none"> thruster.Hank<br clear="none"> <br clear="none"> <br clear="none">      On Monday, July 21, 2014 8:56:11 PM,<br clear="none"> Jon Wallace<br clear="none">  via Personal_Submersibles<br clear="none"> <personal_submersibles@psubs.org> wrote:<br clear="none">     <br clear="none"> <br clear="none">  <br clear="none">     <br clear="none"> <br clear="none">       Dissipation of heat to the water environment via<br clear="none"> conduction with<br clear="none">       the motor housing would help temper overall thermal<br clear="none"> expansion. <br clear="none">       The motors are essentially surrounded by an infinite<br clear="none"> sized water<br clear="none">       jacket and not typically operated at full speed for<br clear="none"> long periods<br clear="none">       of time.  I suspect
 actual thermal expansion of the<br clear="none"> oil in the<br clear="none">       motor housing during typical underwater operations is<br clear="none"> negligible.<br clear="none"> <br clear="none">       <br clear="none"> <br clear="none">       In regards to viscosity effect on the motors,<br clear="none"> JimK's GUPPY is oil<br clear="none">       compensated and three 101's in a K-boat<br clear="none"> configuration and had no<br clear="none">       problem moving that heavy (7 ton?) sub.  Check out<br clear="none">       <a rel="nofollow" shape="rect" target="_blank" href="http://www.youtube.com/embed/u0b7NjxttL4?rel=0&vq=hd720">http://www.youtube.com/embed/u0b7NjxttL4?rel=0&vq=hd720</a><br clear="none"> at<br clear="none">       0:20-0:28 where he just about stops the sub on a dime<br clear="none"> with two<br clear="none">       forward 101's.  Also in<br clear="none">       <a rel="nofollow" shape="rect" target="_blank"
 href="http://www.youtube.com/embed/9Vaq4JK9wVs?rel=0&vq=hd720">http://www.youtube.com/embed/9Vaq4JK9wVs?rel=0&vq=hd720</a><br clear="none"> at<br clear="none">       3:39 he pulls out of the boat lift with just one 101<br clear="none"> aft, and at<br clear="none">       4:02 he pulls out with two forward 101's.  Alec<br clear="none"> has smaller motors<br clear="none">       on SNOOPY but they still have enough power to move it<br clear="none"> around.  I'm<br clear="none">       sure viscosity effect on the motors are measurable but<br clear="none"> from<br clear="none">       practical application it doesn't appear to be much<br clear="none"> of an issue<br clear="none">       when two or more motors are used.  There's enough<br clear="none"> power to move<br clear="none">       the subs as desired even with any viscosity effect<br clear="none"> that is<br clear="none">      
 present.<br clear="none"> <br clear="none">       <br clear="none"> <br clear="none">       Jon<br clear="none"> <br clear="none">       <br clear="none"> <br clear="none">       <br clear="none"> <br clear="none">       On 7/21/2014 10:22 AM, Cliff Redus via<br clear="none"> Personal_Submersibles<br clear="none">       wrote:<br clear="none"> <br clear="none">     <br clear="none">     <br clear="none">       <br clear="none">         <br clear="none">           <br clear="none">             <br clear="none">               <br clear="none">                James, a couple of points.  First, to<br clear="none"> me the fewer<br clear="none">                 the leak paths the better so I would not<br clear="none"> install the<br clear="none">                 added plug.  The issue is how to get traped<br clear="none"> air out of<br clear="none">                 the Md-101 when using oil compensation.  <br clear="none"> I like
 Alec<br clear="none">                 and Hanks ideas for removing trapped air due<br clear="none"> to nipple<br clear="none">                 protruding into body.  The other point is<br clear="none"> the wrap<br clear="none">                 around tube volume can compensate for the<br clear="none"> small amount<br clear="none">                 of air that remains trapped.  To deal with<br clear="none"> thermal<br clear="none">                 expansion of the oil, first of all you are<br clear="none"> dealing with<br clear="none">                 a small volume to start with so the<br clear="none"> tube/reservoir does<br clear="none">                 not have to be all that large.  If you do a<br clear="none"> quick back<br clear="none">                 of the envelope calc on the required volume<br clear="none">                 to compensate for only thermal expansion of<br clear="none"> the oil you<br clear="none">              
   about need 3 US teaspoons for a MK 101 (<br clear="none"> Assume oil has<br clear="none">                 a thermal expansion coefficient of 0.00056<br clear="none"> 1/F and that<br clear="none">                 there is one US pint of oil in the body of<br clear="none"> the 101 and<br clear="none">                 that the temperature swing is 70F to 130F. <br clear="none"> Delta volume<br clear="none">                 is 0.125 gal * 0.00056 1/F * 60F = 0.0042<br clear="none"> gal*128 OZ/gal<br clear="none">                 *6 US TSP/OZ = 3.2 teaspoons).  <br clear="none">               To me the design pressure inside the ME<br clear="none"> 101 should be<br clear="none">                 ambient pressure as they have lip seals on<br clear="none"> shafts.  Lip<br clear="none">                 seals are design to take external<br clear="none"> pressure.  They re not<br clear="none">                 designed to take
 internal pressure.  So a<br clear="none"> simple wrap<br clear="none">                 around tube for oil compensation with say a<br clear="none"> volume of 5<br clear="none">                 US teaspoons should work just fine as this<br clear="none"> would allow<br clear="none">                 for thermal expansion of the oil and a small<br clear="none"> volume of<br clear="none">                 trapped air and because the tube is<br clear="none"> flexible, the<br clear="none">                 pressure inside the 101 is ambient which<br clear="none"> makes the lip<br clear="none">                 seal happy.  As to Alan's suggestion on<br clear="none"> omitting all<br clear="none">                 pressure compensation and only relaying on<br clear="none"> the lip seal<br clear="none">                 without any pressure compensation, I am not<br clear="none"> wild about<br clear="none">                 this idea unless the boat is
 only designed<br clear="none"> for shallow<br clear="none">                 water.  MK designers when they speced the<br clear="none"> lip seals for<br clear="none">                 MK were designing shallow submergence of a<br clear="none"> trolling<br clear="none">                 motor with a factor of safety.  So as you<br clear="none"> get deeper and<br clear="none">                 deeper, you are starting to expose these<br clear="none"> lips seals to a<br clear="none">                 significant differential pressure which<br clear="none"> causes them to<br clear="none">                 overheat and fail at some point.  Is this<br clear="none"> 10ft or 50 ft<br clear="none">                 or 100 ft.  Don't know but to me this<br clear="none"> exposes the boat<br clear="none">                 to some risk particularly if use the<br clear="none"> 101's for depth<br clear="none">                 stability rather than a VBT
 and dive the<br clear="none"> boat negatively<br clear="none">                 buoyant, i.e., vertical thruster fails,<br clear="none">                 boat starts to descend and pilot is<br clear="none"> forced into dropping<br clear="none">                 ballast.  <br clear="none">               <br clear="none"> <br clear="none">               <br clear="none">               To me a bigger question on air vs oil<br clear="none"> compensation is<br clear="none">                 how much power are you giving up with oil<br clear="none"> compensation<br clear="none">                 due to viscosity difference between oil and<br clear="none"> air.  <br clear="none">               <br clear="none"> <br clear="none">               <br clear="none">               As both Alec and Vance point out, there<br clear="none"> has been a<br clear="none">                 lot of bottom time on MD-101s with oil<br clear="none">
 compensation<br clear="none">                 without a lot documented failures.  <br clear="none">               <br clear="none"> <br clear="none">               <br clear="none">               I have not decided in my own mind which<br clear="none"> compensation<br clear="none">                 method I will use on my MD-101's for<br clear="none"> future boats.  <br clear="none">               <br clear="none"> <br clear="none">               <br clear="none">               Cliff<br clear="none">               <br clear="none"> <br clear="none">               <br clear="none">               <br clear="none"> <br clear="none">             <br clear="none">           <br clear="none">         <br clear="none">       <br clear="none">     <br clear="none">     <br clear="none"> <br clear="none">   <br clear="none"><div class="hr" style="margin:5px 0px;padding:0px;border:1px solid rgb(204, 204,
 204);height:0px;line-height:0;font-size:0px;"></div><br clear="none"> Personal_Submersibles mailing list<br clear="none"> Personal_Submersibles@psubs.org<br clear="none"> <a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"> <br clear="none"> <br clear="none">      <br clear="none"> <br clear="none"> -----Inline Attachment Follows-----<br clear="none"> <br clear="none"><div class="hr" style="margin:5px 0px;padding:0px;border:1px solid rgb(204, 204, 204);height:0px;line-height:0;font-size:0px;"></div><br clear="none"> Personal_Submersibles mailing list<br clear="none"> Personal_Submersibles@psubs.org<br clear="none"> <a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br
 clear="none"> <br clear="none"><br clear="none"><div class="hr" style="margin:5px 0px;padding:0px;border:1px solid rgb(204, 204, 204);height:0px;line-height:0;font-size:0px;"></div><br clear="none">Personal_Submersibles mailing list<br clear="none">Personal_Submersibles@psubs.org<br clear="none"><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></blockquote></div></div><br clear="none">
-- <br clear="none">
Sent from my Android device with K-9 Mail. Please excuse my brevity.</div></div><br clear="none"><div class="yqt4205053554" id="yqtfd54399">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="javascript:return">Personal_Submersibles@psubs.org</a><br clear="none"><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></div><br clear="none"><br clear="none"></div></div>  </div> </div>  </div> </div></td>
                                    </tr>
                                </tbody>
                            </table>
                    </div>
                </div>
            </div>