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. ************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. 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