<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span>I thought Gamma had an internal motor.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span>Or is this for something else?</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_6688">You could run a propeller fore & aft of the motor, & the </span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_4068">brushless motors I'm looking at have provision for that.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_4067">But you would need two shaft seals & have that additional friction.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_4792">It would make it more complicated bolting the motor can together.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_4791">If you had the propeller that was back the front, trailing, then the flow</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_4795">created by the forward propeller might help compensate for the inefficiencies</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_6687">of the propeller for reversing.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_6684">A lot of the thruster manufacturers ( of which there aren't many ) publicize</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_6683">the forward & reverse thrust. That might be interesting reading.</span></div><div id="yui_3_16_0_1_1418606052239_4058" dir="ltr"><span id="yui_3_16_0_1_1418606052239_6686">Alan</span></div><br> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1418606052239_4062"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1418606052239_4061"> <div dir="ltr" id="yui_3_16_0_1_1418606052239_4060"> <hr size="1" id="yui_3_16_0_1_1418606052239_4059"> <font size="2" face="Arial" id="yui_3_16_0_1_1418606052239_4065"> <b id="yui_3_16_0_1_1418606052239_4064"><span style="font-weight:bold;" id="yui_3_16_0_1_1418606052239_4063">From:</span></b> hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><br> <b id="yui_3_16_0_1_1418606052239_5465"><span style="font-weight: bold;" id="yui_3_16_0_1_1418606052239_5464">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Monday, December 15, 2014 2:09 PM<br> <b id="yui_3_16_0_1_1418606052239_4814"><span style="font-weight: bold;" id="yui_3_16_0_1_1418606052239_4813">Subject:</span></b> Re: [PSUBS-MAILIST] props<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1418606052239_4071"><br><br clear="none">Alan,<br clear="none">Another idea, make a thruster with a prop at each end of the motor, what do you think?<br clear="none">Hank--------------------------------------------<br clear="none">On Sun, 12/14/14, hank pronk via Personal_Submersibles <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"> Subject: Re: [PSUBS-MAILIST] props<br clear="none"> To: "Personal Submersibles General Discussion" <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"> Received: Sunday, December 14, 2014, 8:04 PM<br clear="none"> <br clear="none"> <br clear="none"> Alan,<br clear="none"> Maybe it is better to make a prop that works in<br clear="none"> both directions. I can afford to loose efficiency, that is<br clear="none"> better than mounting two thrusters in my case.<br clear="none"> Hank--------------------------------------------<br clear="none"> On Sun, 12/14/14, Alan James via<br clear="none"> Personal_Submersibles <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"> wrote:<br clear="none"> <br clear="none"> Subject: Re:<br clear="none"> [PSUBS-MAILIST] props<br clear="none"> To: "Personal<br clear="none"> Submersibles General Discussion" <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"> Received: Sunday, December 14, 2014, 7:04<br clear="none"> PM<br clear="none"> <br clear="none"> Hi<br clear="none"> <br clear="none"> Hank,I guess<br clear="none"> you would be getting the same<br clear="none"> thrust in both directions,<br clear="none"> butyou would<br clear="none"> be doubling the pitch of the propeller by<br clear="none"> doubling up, &<br clear="none"> there maybe a lot<br clear="none"> of turbulance between the propellers.There<br clear="none"> are<br clear="none"> propeller calculators that take a<br clear="none"> number of input variables<br clear="none"> like hp, revs,<br clear="none"> boat size,intended<br clear="none"> speed, diameter of the<br clear="none"> propeller & pitch. You leave one<br clear="none"> input<br clear="none"> out & it calculatesthat for<br clear="none"> you. You<br clear="none"> could call the two propellers one (add the two<br clear="none"> pitches together) & see what diameter<br clear="none"> it calculates for you at a given pitch &<br clear="none"> play around<br clear="none"> till you get the most<br clear="none"> efficientdiameter /<br clear="none"> pitch combination; then<br clear="none"> use the diameter but halve the<br clear="none"> pitch.I<br clear="none"> don't think I made a lot of sense, but if<br clear="none"> you go down<br clear="none"> that path I will explain a bit<br clear="none"> better.However<br clear="none"> given that submarines<br clear="none"> operate better with bigger diameter,<br clear="none"> lower<br clear="none"> pitch propellersit<br clear="none"> probably isn't a<br clear="none"> good idea going to two smaller higher<br clear="none"> <br clear="none"> pitched propellers.Alan<br clear="none"> <br clear="none"> From: hank pronk via<br clear="none"> <br clear="none"> Personal_Submersibles<br clear="none"> <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"> <br clear="none"> To:<br clear="none"> <a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none"> <br clear="none"> Sent: Monday, December<br clear="none"> <br clear="none"> 15, 2014 10:38 AM<br clear="none"> Subject:<br clear="none"> [PSUBS-MAILIST] props<br clear="none"> <br clear="none"> <br clear="none"> Hi All,<br clear="none"> If I build a<br clear="none"> thruster<br clear="none"> with an extra long shaft, then put<br clear="none"> two props on back to<br clear="none"> back, one prop<br clear="none"> reversed. Will the thruster perform equally<br clear="none"> in both directions?<br clear="none"> Hank<br clear="none"> <br clear="none"> _______________________________________________<br clear="none"> Personal_Submersibles mailing list<br clear="none"> <a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"> <a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">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<br clear="none"> Attachment Follows-----<div class="qtdSeparateBR"><br><br></div><div class="yqt6806977733" id="yqtfd56956"><br clear="none"> <br clear="none"> <br clear="none"> _______________________________________________<br clear="none"> Personal_Submersibles mailing list<br clear="none"> <a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"> <a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"> <br clear="none"> <br clear="none"> _______________________________________________<br clear="none"> Personal_Submersibles mailing list<br clear="none"> <a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"> <a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a></div><br><br></div> </div> </div> </div></body></html>