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[PSUBS-MAILIST] dual hull
As I stated I agree with point 5 and 3. On your list are not No.s 1, 2, &
6 the same? If the interior hull were fibreglass, it would be lighter
overall? Even I, the steel guy, would go for a fibreglass hull if it was
guaranteed to only ever see a set pressure (100 psi, 50 psi, whatever) and
was impossible to bump it into something and crack it. What welding
in-between? Maybe none is needed? You would need heavy endcaps to take
the end load, but that isn't insurmountable.
Really all I wanted was for someone to check the math and concept?
Like I said, I didn't really want to be flamed and I wasn't advocating it,
I just thought it was an interesting mental exercise, with possible
benefits?
The major drawback I see is the overall larger displacement (thicker hull),
but perhaps it would be significantly lighter overall, if done right?
And you still have to weigh enough to sink, but that could come from
batteries, or other useful goodies.
Jay.
I still believe that Jeff's 3/4" Fibreglass hull that is light and fast and
good to 1000' is stretching it though. I don't believe that weight is the
problem for speed in a sub, as all subs must have a density close to that
of water, correct??
Ray Keefer
<Ray.Keefer@Sun.COM> To: personal_submersibles@psubs.org
Sent by: cc:
owner-personal_submersible Subject: Re: [PSUBS-MAILIST] Re: Welcome, apologies and multi-hulls.
s@psubs.org
28/01/2003 04:41 PM
Please respond to
personal_submersibles
Hi EM,
Yes, this has been discussed before.
Yes, you can use a multi hull with a bunch of partial pressure zones
and it would work.
The drawbacks make the idea not worth it. They are:
1. Added complexity in construction and welding. All the joints have to
be accessible to weld properly.
2. The partial zones all have to be big enough with access hatches
to allow for welding, inspection and cleaning. Adding cost.
3. The material costs adds up to more then what you would of needed
with a single pressure hull. Three 1/4" plates are more expensive
the a single 3/4" plate.
4. The pressure difference between the interior of the sub and outside
is still the same.
5. Multiple pressure zones adds to the displacement for the size of
interior space. So you get a heavier sub with less room inside.
6. More weld seams create require more inspection. More joints for
possible failures.
Regards,
Ray
> From: emm03@mirapoint.uow.edu.au
> Date: Wed, 29 Jan 2003 08:55:42 +1000
> Subject: Re: [PSUBS-MAILIST] Re: Welcome, apologies and multi-hulls.
> To: personal_submersibles@psubs.org
> Content-Transfer-Encoding: 7bit
>
> Hi People.
> In an attempt to make up for my embarrasing, unhelpful, and
> narrowminded comments I made earlier. I would propose some
> more discussion on this idea of 'compartmentalising'.
> (please excuse any spelling mistakes, I dont possess the
> apparent intellectual capacity of some giants on this list)
>
> Is there any merit in using a multi-layer hull?
>
> For a single layer hull for an ambient machine, the pressure
> differential is at a maximum. If we were to use TWO layers
> (or more) in the pressure hull, and partially pressurise the
> layers in between, then is it not possible to sustain a
> greater TOTAL pressure differential?
>
> I am now going to attempt to draw an ascii illustration..ahem.
>
> The traditional method:
>
> |
> Inside | Outside
> @ | @
> 1atm | 4 atm
> |
>
>
> pressure differential = 3 atm.
> Depth ~30m
>
>
> A multilayer hull:
>
> | |
> inside | Intermed. | Outside
> @ | @ | @
> 1 atm | 4 atm | 7 atm
> | |
>
> Pressure differential per layer is still at 3 atm.
> Outside depth ~ 70m
>
> If I have this right..I think I have it vaguely correct,
> compartmentalising might be a really good way to get to
> greater depths. I know this sort of thing has been discussed
> before, but I am too lazy to look up the archives..
> My apologies for any spelling mistakes Herve, I hope you can
> overlook them just this once.
> If I have overlooked any fundamental physics of hydrodynamics
> and hydrostatics, please be nice!
>
> Thanks!
> EM.
>
>
>
>
>
> ---- Original message ----
> >Date: Tue, 28 Jan 2003 16:21:43 EST
> >From: BauWauHausDesign@aol.com
> >Subject: Re: [PSUBS-MAILIST] Re: Welcome to the
> Personal_Submersibles_Disc ussion
> >To: personal_submersibles@psubs.org
> >
> > In a message dated 1/27/03 5:56:13 PM Pacific
> > Standard Time, dub@linuxmail.org writes:
> >
> > Even if it increased to ambient, or even half of
> > ambient, you would not
> > be able to withstand the bodily strain at the
> > depths in question.
> >
> > Warren.
> >
> > provided that the pressure is ambiant. what if you
> > were able to stratify pressure zones without a
> > structural membrane (ie cockpit, pressure suit...)?
> > to say it is not possible is to deny many example in
> > nature that rely on non-compartmentalized stratified
> > pressure zones to exist.
> >
> > jeffrey
>