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[PSUBS-MAILIST] SCUBA Limits

Hi Mark,
Interesting question, one I've been hashing around myself for about two years now. With the real underlying question being, "What do I want to do with this?" I've come up with three answers. 

---The machine itself.

--- I'll always love the sea.

--- I'm getting older.
Every year here, usually around mini-season for lobster, they drag some poor unfortunate middle-aged guy back to shore whose heart gave out. Sure, it's easy enough to say the words "keep in shape" but, with our busy lives, it gets harder to fit in gym time. In my twenties, I had nothing but time. 

It's tough to get old. You lose respect for your own physical limitations.
I'm thinking about the time I was diving a wreck at 90' and my buddy and I couldn't swim back to the boat through the current. We dropped to the bottom and pulled ourselves to the anchor line, (topside wind did not match bottom conditions, my mistake in anchor placement). 

Sorry to be depressing but, it's tough to get old! :)

Joe









From: "Mark Roberts - Harbortronics" <Mark@Harbortronics.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Welding Revisited
Date: Wed, 25 Jul 2007 23:29:12 -0700

James,
I'd like to pose the question the other direction... if you are gonna stay within scuba limits, why not scuba dive? Sure, a 1ATM sub will keep you dry and comfy, well, comfy may be pushing it. A dry suit will keep you warm and dry if that's the problem. If you are looking for extended down times, invest in a re-breather. It'll save you a mint. If all you want is scuba depths, then there's no particular advantage to 1 ATM either... an ambient pressure vehicle will do the job so much easier.
In my thinking, the only reason for making a real sub is to go deeper, and go places and hopefully see the things I can't see on compressed air. If I was passionate about exploring stuff at 300 ft, then learning to dive on mixed gas will give me the opportunity with less risk and technical issues than a psub.
If the goal is just to make something, a PSub is as good a project as anything, but if the intent is to explore where the pretty fish are, scuba is a heck of a lot easier! 

Mark
----- Original Message ----- From: "Lil Brother LLC" <lil_brother_llc@bellsouth.net> 
To: <personal_submersibles@psubs.org>
Sent: Wednesday, July 25, 2007 9:28 PM
Subject: Re: [PSUBS-MAILIST] Welding Revisited



Joe,

Ok....I'll change my answer to this.......it is possible to survive a
depressurization at 200 feet, but very unlikely. At 900 feet we all know you 
won't, not a chance.( maybe by miracle)

Also.....why go to 900 feet. There is little down there to see. If you are
looking at something down there....you probably shouldn't be. I mean if you are poking around a shipwreck, that is a dangerous place for a submersible. 
Maybe research or something.....but a personal sub...come on. I think I
would like to stay in the realm of regular scuba. If something does go
wrong....at least I have a chance, even if it is a small one.

James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
----- Original Message ----- From: "Joseph Perkel" <joeperkel@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, July 25, 2007 10:23 PM
Subject: Re: [PSUBS-MAILIST] Welding Revisited
".............The statistics would say that you are mistaken. The human body 
(if not
crushed) would be far more likely to survive the pressurization(even
rapidly) at 200 feet,........."
Careful there James. That statement makes me wonder about your appreciation 
for dive physiology.

Big "D" lies at 235' and continues to take it's toll on people who prepare
like this..

http://www.mikey.net/scuba/pics/andrea_doria_july_2001/tami_night_dive.jpg

Joe






From: "Lil Brother LLC" <lil_brother_llc@bellsouth.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Welding Revisited
Date: Wed, 25 Jul 2007 21:03:23 -0500

Dan,

You said the magic words:

"Most psubers won't spend the money to x-ray
their welds , but would'nt you like to know they would pass a test if you
did one ?"

I don't care who the person is, how good they are, there is a possibility
of
the weld failing x-ray inspection. If that were not the case, the U. S.
Navy
wouldn't x-ray every weld on a sub.
Just because a highly qualified welder is diligent and does his best, does 
not mean he will not make a mistake. He is human after all.

You couldn't actually tell if the weld would pass an x-ray unless it is
actually performed. Granted the welder will be very careful about his work, a third person is always less concerned with your safety than you are. This 
is just a fact of human nature.

"If your hull fails at 200 hundred feet you will be just as dead
as if it failed at 900 feet."

The statistics would say that you are mistaken. The human body (if not
crushed) would be far more likely to survive the pressurization(even
rapidly) at 200 feet, but is extremely unlikely to survive at 900.

James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
----- Original Message -----
From: "Daniel Lance" <lanceind@earthlink.net>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, July 25, 2007 8:04 PM
Subject: RE: [PSUBS-MAILIST] Welding Revisited


James,
If you tell a welder his welds are going to be x-rayed when the job is
completed there is a tendency for that person to be more diligent in his
work.
X-ray "quality"welding as it applies to Pressure Vessel Quality work means a bare minimum of porosity, slag inclusions, undercut etc. and no tolerance 
for lack of complete penetration and/ or non fusion in the root pass. A
submarine pressure hull must be built to PVQ standards to acheive 100% of
the hull integrity needed for its intended purpose.Setting the "bar" high
for selecting a weld process, procedure or weldor is whats necessary for
such a demanding application. Most psubers won't spend the money to x-ray
their welds , but would'nt you like to know they would pass a test if you
did one ? If your hull fails at 200 hundred feet you will be just as dead 
as if it failed at 900 feet.
Dan Lance


> [Original Message]
> From: Lil Brother LLC <lil_brother_llc@bellsouth.net>
> To: <personal_submersibles@psubs.org>
> Date: 7/25/2007 12:45:47 AM
> Subject: [PSUBS-MAILIST] Welding Revisited
>
> Ok,
>
> We have discussed welding and the methods involved.
>
> Shouldn't we also discuss the situations that pertain to each type and
the
> critical requirement for each?
>
> I know that a professional welder knows what he is talking about, but I > think x-ray on welds that will never pass regular scuba diving depths > is 
a
> little extreme on the side of safety.
>
> I'm not knocking safety at all, I tend to lean to the safe side of
> everything. But there is a point to overkill when it comes to safety
> measures.
>
> I agree, if you are going to depths of 600 -1000 feet, I would
definitely
> have the most certified welder available, and have the welds tested by
> x-ray.
>
> But I don't see the need to go to that measure if the sub is only going 
to a
> max depth of 200 ft.  I do see the need of the welds being proper,
airtight
> and strong.
>
> But I'm a realist, so I can handle the opinions from whoever disagrees
with
> me.
>
> James Long
> Owner/Designer
> Lil Brother LLC (Instrument Division)
>
>
>
>
>
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