Alec,
Thank you for sharing your experience and insight into the course, it is very much appreciated.
My reference to Jays inertia statement was more of a metaphor for my lack of knowledge in materials in this area and how that is related to expected stressors, particularly large entrained water masses on my design while surfaced in wave action.
http://www.frappr.com/?a=viewphoto&id=269116&pid=1324644
This...is a surface yacht, and although I have figured out how to make this work mathematically as a submersible...practical application of materials scantlings eludes me. To use an aeronautical metaphor, " I don't want to end up using rivets, where I should have used bolts".
But Alec, that is not my only reason to take the Macnaughton course, it goes much deeper than that. You see because...I am the preverbial..."fish out of water."
15 Years ago, I lost my job at Eastern airlines at the same time Pan Am went bust and the industry furloughed thousands. Job / financial security and my future retirement meant more to me than airplanes, so I jumped ship to health care and became a Critical Care RN. My wife did the same, a wise desicison but, I would have been happier doing something else all these years, however, here I stay until retirement in 11 years.
I have always also...loved the sea and have owned various boats over the years, and always, attracted to classic lines. I am beneath the surface, a bit of a "closet artist".
Besides this little submarine, (which I am determined to build), I have had in my mind, locked away and suppressed, various other ideas such as, a little cute but stout tug yacht, a 1920's facsimile of a 32' gentlemans motor yacht with an 8" draft, a plywood flats fisherman....you get the idea.
I discovered something about myself while drawing up this little submarine and I see myself in the not too distant future, drawing up a portfolio of plans like an author types text. Not tied to any employer, I would be free to design what I like and market it as I please, not to make a living but, just to have fun with it! It hit me yesterday in the form of a middle aged epiphany.
Macnaughton now offers the course to be submitted in CAD only and teaches guess what...Rhino. I won't use a single pencil...it's a new era....this is perfect for me.
Thank you so much Alec.
Joe
From: "Smyth, Alec" <Alec.Smyth@compuware.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Yacht Design School!
Date: Sun, 12 Mar 2006 09:15:33 -0500
>Hi Joe,
>
>A couple of years ago I started out with McNaughton's yacht design course.
>First off, let me say I would give it the very highest marks. Unfortunately
>I didn't have the time to continue, but may yet pick it up one day. However,
>I do think I did enough to give you a heads up on what it's like.
>
>I'm originally from Argentina, and I've got a degree in engineering from the
>Merchant Marine University in that country. As you can imagine, at that
>school the course work had an emphasis on naval architecture and marine
>engineering. Vessels were treated as beams, warehouses, or vehicles
>depending on how you looked at them. Nowhere was there any discussion of
>aesthetics, local traditions in boatbuilding, wood construction techniques,
>etc. It was all engineering, similar to what you would get if you were
>designing bridges or industrial machinery.
>
>McNaughton's course has a heavy emphasis on everything related to boats that
>was NOT in my engineering education. You will read lots of books about the
>aesthetics and history of sailboat design. There will be emphasis on using
>good old fashioned drawing with paper and pencil before you move to CAD.
>When you design a vessel in McNaughton's class, those traditions will be
>your starting point. After you have a design, you will use engineering
>calculations to validate it. But it's straight forward things like
>calculating whether the boat is stable. You will probably not see any
>sentences like the one you are referring to. Which is not to say it isn't a
>wonderful course. But you may want to study the basics like physics and
>mathematics.
>
>cheers,
>
>Alec
>
> _____
>
>From: owner-personal_submersibles@psubs.org on behalf of Joseph Perkel
>Sent: Sat 3/11/2006 12:46 PM
>To: personal_submersibles@psubs.org
>Subject: [PSUBS-MAILIST] Yacht Design School!
>
>
>
>Ok, that does it for me now, the straw that broke the camels back. This
>statement 1.92 metric tons-m2/sec2 and 6 mph equals a KE of 7.68 metric
>tons-m2/sec2
>
>Convinces me that there is just too much that I am guessing about in this
>game. I intuitively knew this but, intuitive just ain't good enough to
>invest the time, money, and risk at the level I am contemplating without
>some kind of structured study. My entire adult professional life has always
>been based on structured study anyway.
>
>So my little butt is enrolling in a yacht design course....this one
>http://www.macnaughtongroup.com/school.htm
><http://www.macnaughtongroup.com/school.htm>
>
>before I end up building something that falls apart on me. I've been looking
>at it for some years now anyway....what the hell!
>
>Joe
>
>
>
>
> _____
>
>From: "Jay K. Jeffries" <bottomgun@mindspring.com>
>Reply-To: personal_submersibles@psubs.org
>To: <personal_submersibles@psubs.org>
>Subject: RE: [PSUBS-MAILIST] manned torpedo
>Date: Sat, 11 Mar 2006 09:45:08 -0500
>
>
>
>Bill,
>
>There are issues with concerning the rapid descent of an ambient
>submersible:
>
>1. Many divers can rapidly equalize on a fast descent
>while the ambient submersible pilot has their hands full manipulating the
>sub's controls on a fast dive and may not be able to pinch their nose for a
>Valsalva maneuver. Additionally, for those people that have had the
>pleasure of taking a ride in a hyperbaric chamber, you will have noted that
>it seems to be more difficult to clear your ears while in an air environment
>as compared to when your head is submersed.
>
>2. Bounce dives to deeper depths are an animal unto
>themselves. Recent experiences in the tech diving world points out that a
>slower descent is more advantageous for the subsequent decompression regime
>followed during ascent (note that all dives are decompression dives as our
>ascent rate on supposed no-deco dives is there to allow elimination of
>absorbed gases). Additionally, it has been shown through laboratory
>hyperbaric experimentation that a bounce dive after a previous dive should
>be avoided as the rapid pressurization and depressurization causes a large
>quantity of micro-bubbles to be released and this is very undesirable.
>
>3. Most people when thinking of ambient subs only take
>into account the mass of the sub, it's equipment, and passenger(s). When
>moving, especially fast, the mass of entrained water must also be
>considered. As a simple example, a straight cylindrical (with flat end
>caps) ambient sub that is 24" in diameter (a snug fit and difficult to get
>out of in an emergency) and 12 feet long (I am going to convert to metrics
>here because 1 m3 of fresh water equals 1 metric ton) entrains 1.068 metric
>tons of water. This is a lot of mass especially when considering the
>kinetic energy (KE) the submersible possesses while moving. KE = mass x
>velocity2, therefore every time we double our speed we quadruple our energy.
>For this model case, a speed of 3 mph would equate to 1.92 metric
>tons-m2/sec2 and 6 mph equals a KE of 7.68 metric tons-m2/sec2 This tells
>us:
>
>a. To get up to the high speed is also going to expend a lot of
>energy;
>
>b. Stopping is going to be a bitch; and
>
>c. An out of control, high-speed descent and subsequent meeting with
>the bottom (or other inanimate object) will have unhealthy aspects for the
>submersible and passenger(s).
>
>
>
>Two personal anecdotal experiences to reinforce the KE issue:
>
>1. I was part of the Florida Atlantic University (FAU)
>FAUboat human powered submarine race team a few years back that set a
>world's record for speed in a tow tank located. As an alumnus, was able to
>provide dry suits to keep the team warm and acted as a "catcher/diverter" at
>the end of the tow tank to slow down/stop the high speed runs. FAUboat
>reached just under 4 kts and entrained about as much water as our above
>model case). Since then the speed records has almost double by a Canadian
>team if I remember correctly. As it passed through the speed trap and then
>would put the dive planes to hard rise and the catcher would attempt to grab
>an eye fitting near the bow to also push up and add drag to slow the sub.
>By the end of the day your arms felt like they were going to fall off and
>once in a while you missed and got hit by the sub (BIG HURT'N!!). One
>catcher experienced broken ribs that went unreported at the meet.
>
>2. The USS Ray while running slowly with passive sonar,
>met up with an uncharted sea mount (now named Mount Ray) years ago in the
>Med. I witnessed her deformed bow being cut away by divers at the pier in
>La Mad. It was pushed back on itself in an "S" fold large enough for the
>diver to lay in the fold while cutting. Over 1200 stitches were
>administered by the corpsman and 3 broken limbs were encountered by the
>crew. Many of you may have seen the extensive damage to the LA-class
>submarine that struck another uncharted sea mount in the South Pacific about
>a year ago, A sailor was killed in that accident.
>
>Hope this answers your questions.
>
>Respectfully,
>
>Jay K. Jeffries
>
>
>
>Hi Jay.
>
>
>
>Your post concerning possible injury from rapid decents caused me to wonder.
>I know divers who make quick jump dives
>
>to 200 ft wherein they quickly sink to the bottom and stay about 30 seconds
>and then immediately accend without
>
>decompressing since they did not stay long enough to build up harmful
>nitrogen to make decompression necessary.
>
>They have suffered no ill effects and do this in a very controlled and
>carefully timed way. How does this tie into your post
>
>wherein you warned against barotrauma from too rapidly decending?
>
>Bill Akins.
>
>
>
>
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