<html><head></head><body><div style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;"><div><div>Hi Greg,</div></div><div>Thank you for the input. That is good to know that the captain liked the diesel model. I have been torn over the idea, but since I have an actual engine room with insulated door, it should be fine. My 6 hp motor sounds small now, I can get a bigger one. My problem is it has to fit through a 18 in dia opening with ease so the escape pod can still be an escape pod. Gamma had a 2 hp electric originally with the prop in the centre of the height. I figure the 6 hp diesel should be double that and spin the prop twice the speed. I will take the transmission advice, I have one so no problem there.</div><div>Hank</div><div><br></div><div><br></div><div id="yahoo_quoted_3153971171" class="yahoo_quoted"><div style="font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;color:#26282a;"><div>On Friday, August 11, 2017, 6:31:48 AM MDT, james cottrell via Personal_Submersibles <personal_submersibles@psubs.org> wrote:</div><div><br></div><div><br></div><div><div id="yiv8310526204"><html><head></head><div><div style="color:#000;background-color:#fff;font-family:verdana, helvetica, sans-serif;font-size:13px;"><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11911">Hank,</span></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span><br clear="none"></span></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11913">Captain Kittredge built three diesel subs and liked them very much. He used 7-8 hp yanmar diesels with a transmission. He highly recommended using a transmission and considered reverse a necessity. Exhaust existed at the bottom of the hull just behind a makeshift "skeg" that created cavitation (vacuum to reduce back pressure). </span></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span><br clear="none"></span></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809">The prop should be below center on a sub due to the low center of gravity. If you place a powerful prop as high up as the middle it will lift the stern.<br clear="none"></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span><br clear="none"></span></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11809"><span id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12062">Greg C</span></div><div class="yiv8310526204qtdSeparateBR" id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11840"><br clear="none"><br clear="none"></div><div class="yiv8310526204yahoo_quoted" id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11934" style="display:block;"> <div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11933" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"> <div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11932" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div class="yiv8310526204yqt1107302114" id="yiv8310526204yqt82674"><div dir="ltr" id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_11931"> <font id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12180" size="2" face="Arial"> </font><hr id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12179" size="1"> <b><span style="font-weight:bold;">From:</span></b> hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none"> <b><span style="font-weight:bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br clear="none"> <b><span style="font-weight:bold;">Sent:</span></b> Thursday, August 10, 2017 5:14 PM<br clear="none"> <b><span style="font-weight:bold;">Subject:</span></b> [PSUBS-MAILIST] Gamma's diesel engine<br clear="none"> </div> <div class="yiv8310526204y_msg_container" id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12159"><br clear="none"><div id="yiv8310526204"><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12158"><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12157" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:small;"><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12156">Hi All,</div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12173">I have just purchased a 6 hp diesel for Gamma. The plan is to use the original prop assembly that can jettison. The only thing I am not sure of is will I have cavitation problems. The prop will be about 12 inches from the occupant sphere, mounted in the centre of the sphere (equator) </div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12175">Will I have to put a spacer between the sphere and prop assembly to move it further away?</div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12161">Hank</div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12177"><br clear="none"></div><div id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12171"><br clear="none"></div></div></div></div>_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a rel="nofollow" shape="rect" id="yiv8310526204yui_3_16_0_ym19_1_1502453497437_12164" 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></div> </div> </div> </div></div></div></html></div><html><div class="yqt1107302114" id="yqt09366"><body>_______________________________________________<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"></body></div></html></div></div></div></div></body></html>