RE: [PSUBS-MAILIST] Open Discussion's Allowed in PSUB's Mailing List

Brent,

You make a valid, reasoned, and well thought out response. I may have been tired and too crotchety when responding to your post…way to rough with the bubbling enthusiasm that you constantly display. The point is that we must all consider when we post what the consequences are potentially for some newbie that is only a lurker on the list and thoroughly reads the archives without true understanding. I am adamant on this point as there is a responsibility to others. I read every post and do not block those senders that in my opinion are off the wall…once in a while they present nuggets of wisdom or a link to some information that opens up a new avenue of thought on how to approach an issue from a different direction (boy do you have to wade through a lot of BS to get there J). Open discussion is valuable but it should be prudent and measured.

It is not the job here of members to teach others how to design and build subs. While some of that does occur, the onus is on the individual to do some basic research. The prudent person should cross-reference any serious matter presented here as the credentials of many presenters here is unknown. While you don’t have to certify your boat to ABS Rules, the prudent person should read this free resource and use the Rules as guidance in building their submersible. That person needs to fully understand the hull strength spreadsheet, where the calculations come from, their limitations, and that if a particular hull type is not covered then there is a pretty good reason why an amateur should not attempt to configure their sub with an unusual hull shape. Every naval architecture text and school tells you that you need to start a “Weights & Moments” spreadsheet the minute design is commenced…otherwise you end up with an unstable sub (most think of only static stability on the surface, surfaced dynamic stability and underwater stability can make a statically-stable, great looking submersible into a hell ride). A submersible is an expensive endeavor, if you can’t afford a few basic reference texts how will you be able to build even a small simple sub? The money spent on PVHO and Dr. Stachiw’s text is money well spent that will save money when building your sub and even may save your life. Dan Lance also suggested as a welding reference Gas Metal Arc & Flux Core Parameters by Ed Craig.

Joe Perkel has a great approach to submersible design. He focuses on his conceptual design and repeatedly fends off questions pertaining detailed design that he can’t immediately answer. Often the answer presents itself later or is learned as experience is gained through the design process. Unfortunately quite a few people rush out and buy steel early on without properly understand ALL of the basics of submersibles. They end up with a dangerous sub or one that they feel uncomfortable with taking below 20 feet once they learn more. They exerted the same effort and spent the same dollars that would be needed for a proper K-350. Please remember while you may be comfortable with a higher than normal level of risk in operating your submersible, a failure on your part reflects poorly on the PSUB community and may lead to government intervention. A little guidance that I have found fruitful in the approach to many things, “Would I feel comfortable with a loved one using this item or having this person take care of my loved one?” We all are more willing to risk more with our life than risk others but we need to consider the consequences. And if you decide not to heed what is here, “Shear stupidity is self correcting”. Maybe Dan Lance can repost a previous email that I posted that several members noted was very valuable in guidance on submersibles and design.

R/Jay

Jay K. Jeffries

Andros Is., Bahamas

A skimmer afloat is but a submarine, so poorly built it will not plunge…

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig
Sent: Wednesday, August 22, 2007 5:11 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Open Discussion's Allowed in PSUB's Mailing List

Jay,

I've heard a number of times in the past how some choose to be blunt with new comers to the group and/or amateurs in the field of subs. I think one can be straight forward with important information in a way that doesn't come off as rude or disrespectful to those that lack or one believes, lacks there expertise and experience in that area. This group is primarily for, and always has been for learning and exploring of how to design, build, and safely operator ones own sub through open discussions and sharing of information and/or hardware with amateurs and experts alike.

Perhaps there is a need for a new forum for a select group of individuals that don't wish to deal with teaching and/or reading what amateurs are talking about, and want only very serious factually accurate post in there group. To join this group one would need to have done more then 500 dives in a sub worth more then $100,000, and/or been in the submarine field professionally for more then ten years, and/or they have a doctorate in a related field.

I've seen discussions more or less shut down by a type of intimidation, on subject matter that some were tired of discussing and/or not interesting in. I think that is wrong for this group, and that if one doesn't want to read and/or respond to subject matter(s) they are tired of and/or not interested in, it is very easy to just delete all messages with said subject matter and/or content. We will hopefully always get new comers into this group with basic questions and great new insights to old problems, and they shouldn't be required to read and understand the whole PSUBS archive before they post a question to the group. I spend a massive amount of my time researching subs and related data, and I barely have time to read and try to fully understand the current emails from the list, let alone read and understand the whole archive. Perhaps I'm slow, and if that's the case then I'm ok with that. Those are the jeans my parents gave me, and I'm happy to have what I got.

I once posted a question about whether or not I needed to anneal acrylic, if I only cut it with a aqua jet cutter. Since I had reason to believe the aqua jet cutting process wouldn't put any heat stesses on the acrylic that would need annealing to take care of. I did a PSUB's archive search before I posted my question. Along with the speculation that my question wouldn't be answered in a great but slightly dated $200 book, (I hadn't aquired yet) since I believed aqua jet cutting of acrylics was basicly a new process, I asked the question. I got the patt answere of that, all acrylic needs to be annealed after cutting, in such a way I couldn't tell if they really knew that, with regards to my question, or if they just didn't want to deal with it. Then they shut the discussion down by intimidation by being an expert in the group (most don't want to perturb) and stated that the topic was basicly old and dead.

When I said, " How about an non educated guess. ; )' " that was tough and cheek Jay.

In my opinion, I'm reasonably well educated and practiced in a fair number of areas, and I worked very hard to get to where I am today. I have so many skill sets and interest it's hard to keep on track most days. Almost everything is of interest to me. Many far more negative people then you, have tried to get me to hide in a corner because I've chose a very different path then them selves. You can see the result.

I would guess that for most of us here in this group, this is a passionate hobby of there's. Hobby's are supposed to be fun and enriching, not negative things that suck the life out of you.

We have talked about using the KISS (Keep It Simple Stupid) principle for sub design. I agreed with you that one should do that if at all possible. How simple is simple? The fact is that most subs in order to have the capabilities one wants them to have, can't have all aspects of there design be simple.

Just recently you gave me a link for a book called Simplicity in Design, as a response to one of my post. Again I ask, how simple is simple? It's all subjective to ones brain power and understanding of how things work. What makes art beautiful? It's mostly all in ones head.

During that same period in your post in response to mine, you made it sound pretty clear that I shouldn't post to this group until I read and understood the ABS manual and reams of other technical manuals, science articles, and books relating to sub design and operations. If I and or others were required to do that, then it would likely be years before we could post here.

"Instead of “guessing” all of the time, please do some real research."

I do massive amounts of research almost every day before I send most of my longer post to the group. But at some point with all the massive amounts of data out there on the net, one just needs to post a question or two to the group and see if anyone can, or is willing to give some insight, or even give a guess, that can help discover the answere.

I'm not interested in perturbing or annoying anyone on this group. I'm here primarily to learn and share what I've learned.

Since many subs are military or trade secrets for large organizations, many times we are left guessing why they designed it a certain way. It's a mystery, and who doesn't love a good mystery. It's like a puzzle that with enough brains but to task can figure it out or find someone that can.

I think that if the MIR subs have one or more very large drop weights, that if dropped could make vortex shedding a problem that the rear stabilizer would be very helpful in dealing with.

When I said I don't know if that is a Kort or Rice nozzle, that was a prompt for someone that does really know to please speak up and so we could learn more about the sub.

"I can tell you from an early proposal for building the Mir subs that they are size constrained for carrying in aircraft holds and the fins on top are probably a means for shortening the overall length due to deck housing issues (this is a factor in a number of submersible designs)…but it is pure speculation on my part."

So why is it you can speculate and I can't? I had reason to believe I had a couple of possible good reasons they designed the rear stabilizer the way they did and I was bouncing them off the group for an open discussion to pool the groups large knowledge base. I don't know how many times colabortion with others has produced wonderful things in my life and others. If I had a part of a good idea, one or more people would come along and fill in the blanks and make it a whole good idea.

"Neophyte PSUBers often take as gospel any information that is found here on the PSUB list and can lead to misconceptions on their part in the future…some of which may be dangerous if not down right deadly."

I would expect anyone with the were-with-all to build, and then operate there own sub wouldn't believe that this "DISCUSSION" groups postings are all, or even mostly all the gospel truth. Such a person wouldn't likely able to read and understand enough of what this group is talking about to hardly get started on there own sub, let allot survive the walk to the garage.

Regards,

Brent Hartwig

From: bottomgun@mindspring.com
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIR aft planes
Date: Tue, 21 Aug 2007 15:59:28 -0400

Brent,

Instead of “guessing” all of the time, please do some real research. Neophyte PSUBers often take as gospel any information that is found here on the PSUB list and can lead to misconceptions on their part in the future…some of which may be dangerous if not down right deadly. You will note that many of us refrain from making replies here unless we have some expert knowledge to bring. A number of us have to waste a good deal of time better spent on other endeavors dispelling misinformation that is either represented as fact or not clearly labeled speculation by a non-engineer or scientist.

I did not respond to this particular request by Joe as I do not know why the Russians have used this configuration but I can tell you it is not because the water is not disturbed yet and vortex shedding is not an issue here. Both issues are related to speed here and speed is not one of Mir’s fine points. You can not tell whether it is a Kort nozzle, a Rice nozzle, or simply an entanglement guard without viewing the cross section of the nozzle or someone more closely associated with the Mir submersibles making a response. Due to the small size of most all submersibles, there is little reserve buoyancy that can be effectively designed in…all of them have handling issues on the surface. While a lot can be learned from images and visiting various submersibles, hard calculations along with weight and trim spreadsheets are necessary prerequisites for a successful submersible with a long, safe lifespan. How do you know you are not looking at a given submersible’s weak point or a poor design?

I can tell you from an early proposal for building the Mir subs that they are size constrained for carrying in aircraft holds and the fins on top are probably a means for shortening the overall length due to deck housing issues (this is a factor in a number of submersible designs)…but it is pure speculation on my part.

A dunce can appear brilliant if he holds his tongue.

Jay K. Jeffries

Andros Is., Bahamas

A skimmer afloat is but a submarine, so poorly built it will not plunge…

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig
Sent: Tuesday, August 21, 2007 2:39 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIR aft planes

How about a non educated guess. ; )'

Thanks for the link to the pic Joe. I would "GUESS" that the aft plane is controlled my the pilot directly or by hydraulics or the like. The swept-back feature is for coolness factor Joe. Na for that I would say it helps if you lightly hit some thing you'll just bounce off and keep going instead of braking the aft plane, but more importantly I would say its for reducing entanglement issues. That is why I like to have surfaces on my sub rounded over and swept back to some degree, with no item protruding forward like the weapons systems on the Star Wars X-wing fighter.

On another note since the aft plane is acting like a planes elevator, having the said aft plane up and out of the way of the swirling water coming off the subs hull, gives the pilot more control then if its down and directly behind the sub. This is why allot of ships are now using forward facing props, that pull instead of push. This is more efficient since the water hasn't be really disturbed yet and you can get a better directional bit into it.

I would say that the whole stabilizer assembly also really helps to deal with vortex shedding. But for that I would use a larger assembly.

I like the Kort nozzle on the sub, or is that a Rice nozzle? From what I understand the Rice nozzle is more efficient.

I wish they would add some soft saddle tanks to the Muir subs, to give them more freeboard staybility. Allot of people get really sick in them when at the surface. Watching the Zodiac cowboys try to attach the crane cables to the subs in rough water is one of the reasons I started designing trimaran subs. I know that adding tanks to the subs gives them more hydo drag, but that is another one of these trade-offs we have been talking about.

Regards,
Brent Hartwig

> From: joeperkel@hotmail.com
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] MIR aft planes
> Date: Tue, 21 Aug 2007 12:15:46 +0000
>
>
> Can someone please explain to me the precise function and mechanics of the
> aft planes / stabilizer on the MIR submersibles?
>
> In this image, you can see it rotated at an exaggerated angle, which makes
> me wonder if this was done mechanically by the pilot from within, or the
> unit is "free pivoting" for some reason which escapes me.
>
> http://www7430.nrlssc.navy.mil/7432/hydrates/images/Muir_1.jpg
>
> Why then I also wonder, the extreme sweep-back of these planes? You see this
> in aircraft for aerodynamic purposes in the transonic flight envelope
> (airliners) but, why here? This is repeated in both MIR's as well as the
> proposed Alvin replacement.
>
> Any info is most appreciated, even an educated guess.
>
>
> Joe
>
>
>
>
>
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