<html><head></head><body><div style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;"><div>Hi Cliff,</div><div>The 12.5' length is overall. Maybe I'll have to dip into my Roth IRA and add those stiffeners sooner than I thought. Thank you!</div><div>God bless, Jim</div><div id="yahoo_quoted_6600296797" class="yahoo_quoted">
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On Wednesday, August 29, 2018, 4:25:03 PM PDT, Cliff Redus via Personal_Submersibles <personal_submersibles@psubs.org> wrote:
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<div><div id="yiv8005897176"><div><div dir="ltr"><div>Jon/Jim there is not enough info in the thread to do this ABS stress calculation rigorously. Not sure if the 12.5' length is overall or SS (seam to seam). Also we need details of stiffeners including dimensions of the inner stiffeners and spacing. The ABS spreadsheet is for stiffened cylinders. As you note, you can trick the spreadsheet by putting some stiffeners in with 0.001 web and flange thickness. If you do this, then you need to ignore results (maximum allowable working pressures) associated with stiffeners and just look at the depth associated with overall buckling. With this diameter of a hull, even with 0.625" wall it really should have stiffeners to address the concern of overall buckling. This is what happens on an externally pressured unstiffened cylinder when overall buckling occurs.</div><div><br clear="none"></div><div>Cliff</div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div></div><br clear="none"><div class="yiv8005897176gmail_quote"><div class="yiv8005897176yqt0652899617" id="yiv8005897176yqt16120"><div dir="ltr">On Wed, Aug 29, 2018 at 10:09 AM Jon Wallace via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"></div><blockquote class="yiv8005897176gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:16px;"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span></span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_29607">I'd like to see Cliff and Sean respond. </span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span><br clear="none"></span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_29981">The unstiffened cylinder calculator and Cliff's hull spreadsheet are pretty close, the former at 315 feet and latter at 308 feet. Both are based upon ABS rules but Cliff's spreadsheet does consider some of the finer and nuanced points of failure. There is one section of Cliff's spreadsheet calculator (inertia requirement) that shows a cause of concern but I think it is due to the fact that his spreadsheet requires stiffeners for this section to be calculated correctly and I assume Jim's cylinder has none. The spreadsheet will not accept "0" for a stiffener dimension to simulate a cylinder with no stiffeners, so I usually enter ".01" as a value with the distance between stiffeners the overall length of the hull to represent an insignificant stiffener effect. Using .01 for stiffener values, the "inertia requirement" section shows max depth of 5 feet. Using K-boat stiffener values the same section shows max depth of 101 feet, and using more appropriate stiffener values for this hull of .625 thickness and 2 inch flange the same section shows max depth of 227 feet. Now, I'm pretty sure...would bet money on it...that Jim's hull will easily survive 5 foot of depth without collapsing so I don't know how to really interpret the inertia requirement section of the spreadsheet in this case.</span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><br clear="none"></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411">Sean's calculator doesn't seem to take into account cylinder length so I couldn't use it as a triple check on the other two calculators.<br clear="none"></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span><br clear="none"></span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_30277">At this point Jim, I would tread cautiously with max depth until you (or we) are comfortable with a figure. Personally, I think your original max depth of 100 feet is reasonably appropriate. An unmanned test dive when the sub is ready would be highly encouraged.</span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span><br clear="none"></span></div><div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28411"><span>Jon</span></div><div class="yiv8005897176m_7451833063694151005qtdSeparateBR" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28326"><br clear="none"><br clear="none"></div><div class="yiv8005897176m_7451833063694151005yahoo_quoted" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28263" style="display:block;"> <div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28262" style="font-family:times new roman, new york, times, serif;font-size:16px;"> <div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28261" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div dir="ltr" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28304"> <font id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28324" size="2" face="Arial"> </font><hr id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28323" size="1"> <b><span style="font-weight:bold;">From:</span></b> james hughes via Personal_Submersibles <<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"> <b><span style="font-weight:bold;">To:</span></b> Alan via Personal_Submersibles <<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"> <b><span style="font-weight:bold;">Sent:</span></b> Tuesday, August 28, 2018 9:24 PM<br clear="none"> <b><span style="font-weight:bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Lurker finally surfacing!<br clear="none"> </div> <div class="yiv8005897176m_7451833063694151005y_msg_container" id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28260"><br clear="none"><div id="yiv8005897176m_7451833063694151005yiv3125103855"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28259"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28258" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28257"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28256"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28255">Thanks Allen for that hull calculation! I hope you're right! I thought it might be shallower than that without reinforcement. I've tried to build a good safety margin in all the parts on the boat (using thicker steel in the conning tower, for example, than what the K250 plans called for). Still, this being my first boat I don't really want to go deeper than I could safely get up from on SCUBA (I've got a 2" flood valve if I ever need to get out while on the bottom). Plus most of the sea life I'm hoping to see is usually in shallow water. But you're right, little more investment now may make a difference if I decide to go deeper for some reason in the future. </span></span><br clear="none"></div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28337"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28426"><span id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28425">THANK YOU again and God bless, Jim</span></span></div><div class="yiv8005897176m_7451833063694151005yiv3125103855yahoo_quoted" id="yiv8005897176m_7451833063694151005yiv3125103855yahoo_quoted_5988626133" style="display:block;">
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On Monday, August 27, 2018, 2:51:34 PM PDT, Alan via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:
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<div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28345"><div id="yiv8005897176m_7451833063694151005yiv3125103855"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28344"><div></div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28432">Hi Jim,</div><div>thanks for the introduction, and welcome along.</div><div>Can't help you with the seals as my motors are external.</div><div>I have been making my own thrusters & have contacted seal reps &</div><div>even emailed the manufacturer for advice on a non standard mounting</div><div>method I was proposing. Normally seals are used on pumps to keep</div><div>fluid that is under pressure in rather than out as in our case.</div><div>I did a quick calculation on your pressure vessel & it came out as a 600ft</div><div>crush depth. Don't take that as gospel, but it may be worth looking at it</div><div>in depth if you haven't already. If the 600ft is right you could dive to 300ft</div><div>with that hull! For all the work that goes in to building a submarine you may</div><div>find that it is only a relatively small amount of extra effort & cost to give</div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28343">you an extra 200 ft of diving capability. I would think about this first before</div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28347">choosing a seal as the added pressure may have bearing on your choice.</div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28349">All the best,</div><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28351">Alan (New Zealand)</div><div class="yiv8005897176m_7451833063694151005yiv3125103855yqt0133855491" id="yiv8005897176m_7451833063694151005yiv3125103855yqt48657"><div id="yiv8005897176m_7451833063694151005yui_3_16_0_ym19_1_1535544838254_28353"><br clear="none"></div></div></div></div></div></div></div></div></div></div></div><br clear="none"><br clear="none"></div> </div> </div> </div></div></div>_______________________________________________<br clear="none">
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