<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:14pt"><div><span>Jim,</span></div><div><span><br></span></div><div><span>There lies the blow and go last resort. Clever design huh? I wish I had met the man.</span></div><div><span><br></span></div><div><span>I have seven years to finalize a design and part of my decision point is whether of not to exceed sport diving depth. Around here, I don't have to, there's plenty to do and see in relatively shallow water.</span></div><div><span><br></span></div><div><span>This is why I am so tempted to upsize to something North of a K-350, but well South of Kraka. I wonder what you get if you breed a Delta and a Freya? :)</span></div><div><span><br></span></div><div><span>Joe</span></div><div><span><br></span></div><div><span><br></span></div><div class="yahoo_quoted" style="display: block;"> <br> <br> <div
 style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 14pt;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div dir="ltr"> <font face="Arial" size="2"> On Saturday, November 30, 2013 12:05 AM, "jimtoddpsub@aol.com" <jimtoddpsub@aol.com> wrote:<br> </font> </div>  <div class="y_msg_container"><div id="yiv9767629484"><div><font color="black" face="arial" size="2">
</font><div><font size="3" style="background-color: transparent;">Joe,</font></div>

<div><font size="3"></font> </div>

<div><font size="3">That brings up another design standard.  If everything except the pressure hull itself floods, the release of the drop weight must result in positive buoyancy.  So if both battery pods and all ballast tanks flood, you should still be able to surface by releasing the drop weight.  If the drop weight also sticks, you're screwed!</font></div>

<div><font size="3"></font> </div>

<div><font size="3">Jim</font></div>

<div></div>

<div></div>

<div style="color: black; font-family: arial, helvetica; font-size: 10pt;">-----Original Message-----<br clear="none">
From: Joe Perkel <josephperkel@yahoo.com><br clear="none">
To: personal_submersibles <personal_submersibles@psubs.org><br clear="none">
Sent: Fri, Nov 29, 2013 10:27 pm<br clear="none">
Subject: Re: [PSUBS-MAILIST] Stability & Buoyancy<br clear="none">
<br clear="none">




<div class="yiv9767629484yqt6969894133" id="yiv9767629484yqt37865"><div id="yiv9767629484AOLMsgPart_2_7acb4649-e0cc-4657-8a53-23089ef17dca">
<table border="0" cellspacing="0" cellpadding="0"><tbody><tr><td valign="top" rowspan="1" colspan="1">This issue, explains the existence of the snorkel in the K-350. Imagine for a moment, the loss of a MBT, or the flooding of a battery pod.<br clear="none">
<br clear="none">
I tell you, a lot of thought went into this little boat. Every time I look to exceed the parameters, I see better the original intent. Every time!<br clear="none">
<br clear="none">
Joe<a href="http://overview.mail.yahoo.com/?.src=iOS" target="_blank" rel="nofollow" shape="rect"><br clear="none">
<br clear="none">
Sent from Yahoo Mail for iPad</a></td></tr></tbody></table>            
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                            <b>
                                <span style="font-weight: bold;">From:</span>
                            </b>
                            <a href="mailto:jimtoddpsub@aol.com" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:jimtoddpsub@aol.com">jimtoddpsub@aol.com</a> <<a href="mailto:jimtoddpsub@aol.com" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:jimtoddpsub@aol.com">jimtoddpsub@aol.com</a>>;                            <br clear="none">

                            <b>
                                <span style="font-weight: bold;">To:</span>
                            </b>
                             <<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>;                                                                                                     <br clear="none">

                            <b>
                                <span style="font-weight: bold;">Subject:</span>
                            </b>
                            Re: [PSUBS-MAILIST] Stability & Buoyancy                            <br clear="none">

                            <b>
                                <span style="font-weight: bold;">Sent:</span>
                            </b>
                            Sat, Nov 30, 2013 3:45:36 AM                            <br clear="none">

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<div><font size="3">Yeah, Jon, the concept of a keel tank seems a bit spooky.  Trim tanks are often at the bottom of the boat but not below it, and their function has more to do with trim weight than with buoyancy. </font></div>



<div><font size="3"></font> </div>



<div><font size="3">To clarify what I said:  "The lower your tanks, the greater your freeboard, but less            CB/CG spread."  That's true when the tanks are intersecting the water line.  Once they are completely below the water line, moving them any lower isn't going to give you more freeboard, but it will lower your CB.   Not good.</font></div>



<div><font size="3"></font> </div>



<div><font size="3">Jim</font></div>



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<div style="color: black; font-family: arial, helvetica; font-size: 10pt;">-----Original Message-----<br clear="none">
From: Jon Wallace <<a href="mailto:jonw@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:jonw@psubs.org">jonw@psubs.org</a>><br clear="none">
To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">
Sent: Fri, Nov 29, 2013 9:10 pm<br clear="none">
Subject: Re: [PSUBS-MAILIST] Stability & Buoyancy<br clear="none">
<br clear="none">





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      I'm somewhat a novice with CG and CB but it does occur to me that
      the illustration in the document shows a circumferential ballast
      tank which from the perspective of CB must be the worst type to
      employ.  The K-350 design with both drop weight and battery
      compartments well below the ballast tanks provide an extremely low
      CG with CB well above it at all times. <br clear="none">

      <br clear="none">

      <br clear="none">

      On 11/29/2013 9:54 PM, <a class="yiv9767629484moz-txt-link-abbreviated" href="" rel="nofollow" shape="rect">jimtoddpsub@aol.com</a> wrote:<br clear="none">

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    <blockquote type="cite"><font color="black" face="arial" size="2">
        
</font>
<div><font size="3" style="background-color: transparent;">Hi
            Alan,</font></div>


        

<div> </div>


        

<div><font size="3">Re: "the centre of buoyancy moving upward
            past the centre of gravity... "  This implies that somehow
            the centre of buoyancy had been <i>below</i> the centre
            of gravity which would be really, really scary.  The ABS
            rule (per Cliff's spreadsheet) is that the CB must be at
            least 2" <i>above</i> the CG when the sub is submerged. 
            In the event the drop weight is released, the CB must still
            be at least 1" above the CG.  Frankly, that narrow a spread
            doesn't meet my comfort zone.</font></div>


        

<div> </div>


        

<div><font size="3">When the sub is surfaced, any portion above
            the water line is now dead weight since it is no longer
            displacing any water.  When that same portion was submerged
            it was contributing buoyancy.  Therefore the
            above-the-water-line portion contributes to the CB moving
            downward.  Offsetting that is the fact that the main ballast
            tanks were contributing little or no buoyancy to the extent
            they were full of water when the sub was submerged.  Once
            they are filed with air they move the CB upward.  If the
            tanks are fore and aft as on the K-boats, they are located
            even with the top of the cylindrical hull.  However remember
            that the portion of the ballast tanks now above the water
            contributes no buoyancy.  With the fore and aft tanks, the
            tanks don't contribute much to lateral stability
            (anti-roll); you're dependent on the CB/CG spread for
            lateral stability.  I'm purposely staying away from
            any direct discussion of metacenter for now.</font></div>


        

<div> </div>


        

<div><font size="3">My MBT's are fore and aft.  My original plan
            for setting design procedures for adding saddle tanks was
            this:  Calculate where the surfaced water line would be <u><i>if</i></u>
            I installed the saddles at 4:00 and 8:00 positions, then
            actually install them higher so that the top of the saddles
            would be right at the water line.  This would give me
            maximum lift and freeboard since no part of the saddles
            would be above the water line.  However Alec correctly
            pointed out that having a portion of the saddles above the
            water line contributes to anti-roll since the down-rolling
            tank would then provide extra displacement and buoyancy to
            push that side back up (handy if someone steps on that side
            of the sub<font face="Arial, Helvetica, sans-serif">).</font> 
            The lower your tanks, the greater your freeboard, but less
            CB/CG spread.  The higher your tanks, the greater your
            surface stability, but you sacrifice freeboard.  The design
            challenge is finding the optimum level.</font></div>


        

<div> </div>


        

<div><font size="3">Jim</font></div>


        

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