[PSUBS-MAILIST] Terminating a conical transition

Sun May 4 17:53:30 EDT 2014

Hank,

Most boats see about 100 hours use a year. I expect this to be no different. I want a neat little toy to play with in the garage on the occasions when my wife turns me loose! :)

This is why I want to section the hull,...and I just convinced myself to shorten the thing a bit!

Joe

On Sunday, May 4, 2014 5:45 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Joe,
Sounds like you need to have the longest cones possible at each end to reduce the size of the free flooded areas.  Another option is to change the design, decide what your priorities are.  What is most important? if long transits are the plan then you may need to change things.  If fuel cost is a consideration, another change.  Looking very cool dock side, you nailed it. It just wouldn't be fun if it was easy.
Hank
--------------------------------------------
On Sun, 5/4/14, Joe Perkel via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Subject: Re: [PSUBS-MAILIST] Terminating a conical transition
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Received: Sunday, May 4, 2014, 5:30 PM

Sean,
Have
you ever notice how the Civil War design of the USS
Alligator stabilized the boat submerged? A couple of crazy
little tethered floats, but the rationale has
never escaped me.
I
will reduce free flood space wherever I can. Trapped
inertia being on my mind, but I needed someone to remind me
of the waste in efficiency / power requirements,
thanks! Also, your comments bring home some compelling
reasons to shorten the design with a "Just
enough but no more" design
mindset.
I've
given thought to the conical section in the front, I can
reduce this down to a 30" head with forward viewing ala
Kraka, but quite the tight fit! Not sure, I have to give it
some more thought.
If
I reduce the aft end with a cone, then I would bring the
motor inside and do a standard marine hybrid
installation. Expensive, but certainly a more reliable
answer. If I do that, I would dispense with the notion of
propulsion units in the aft end of the pods, truly no
  need then. This boat requires a  massive
ventilation / climate control scheme for surface operations,
that's why I've been overly generous with the
machinery space in these early drafts.
I'm
still concerned about stability because I have to contend
with what to do with all of that centerline space. The VBT
would take up some, but I would have to flood the
rest.
Thanks
again Sean!
Joe
     On Sunday, May 4,
2014 4:56 PM, Joe Perkel via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
     Hank,
What
you see there is the
  original Seehund arrangement, my intention is as you say,
up higher. The aft cone on mine essentially now an MBT.
Those lower volumes will be flooded in practice, but I am
wondering if they could be blown down dry to help with
trailer launching and recovery??
Plenty,
and I mean plenty of room along the centerline for keel
ballast.
I
keep thinking about what you've told me regarding Gammas
attachment, always in the back of my
  mind!
Thanks
Hank!
Joe
     On Sunday, May 4,
2014 4:34 PM, hank pronk via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
     Joe,
Your dive tanks are to low, they should be at
the top of the sub.  The way you have it will be less
stable.
The motor pod should be okay, just
like the K subs. You do not want your torpedo's to be
buoyant, they should be as heavy as possible for
stability.
Hank
--------------------------------------------
On
  Sun, 5/4/14, Joe Perkel via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:

  Subject: Re:
[PSUBS-MAILIST] Terminating a conical transition
  To: "Personal Submersibles General
Discussion" <personal_submersibles at psubs.org>
  Received: Sunday, May 4, 2014, 3:07 PM

  I've incorporated
  some of the suggestions in the attached
drawing. Still,
  I've got a lot to think
about here but I am also excited
  about the
possibilities and the potential outcome. This
  image should give some idea of
  what's on my mind.
  What you see is the
water ballast arrangement
  on the original
Seehund, and how my proposed pressure

boundary fits into this scaled down version. The
following
  is a list of concerns and or
design
  considerations.

1)
  Clearly, I have no need to compensate
for the loss of

  torpedoes
  2)
  New pressure
boundary provides for massive MBT volumes

(Low pressure compressor to blow down

volumes)
  3)
  Torpedo
battery pods may need to incorporate some free
  flooding spaces to reduce weight, or perhaps
reduce battery capacity to a single pod in

lieu of the former forward water ballast tank, then
  completely free flood both torpedoes
completely??.
  (Boat will incorporate a
gen-set)
  4) Questionable

reliability of external motor pod assembly.

5)
  Stability considerations
  Thanks for the input
  gents,
It really helps me to take a step back on

occasion!
  Joe

      On
Sunday,
  May 4,
  2014 10:19 AM, hank pronk via
Personal_Submersibles
  <personal_submersibles at psubs.org>
wrote:
     Joe,

When I mounted the tanks back on
  Gamma, I changed the
  mounting location to
give a greater angle also I did what
  Vance
is saying on a small scale.    I then poured
  a gallon of paint in 
  each tank and rolled the sub slowly to
ensure there was
  complete paint
coverage.  If I was operating in salt

water I would mount some nipples to the tanks with
  plugs.  After a dive in salt water,
remove the plug and
  you have access to
spray fresh water inside and rinse the
  salt
water out. A large panel is a good idea also because
  you
  can open it up after each
dive and let it dry out.   
  If I
had a K350, I would not copy the Nekton tanks
  exactly.  I would change the shape so
they have more
  volume at the top reducing
the
  rolling effect. Also I would
  consider
making them from SS. Also SS heads solves the
  problems entirely. Start watching ebay for ss
heads.  I
  once saw a ss tank exactly
the
  same as a 500gal propane tank
  for 1,500
dollars on ebay.
  Hank

--------------------------------------------
  On Sun, 5/4/14, via Personal_Submersibles
<personal_submersibles at psubs.org>
wrote:

Subject: Re: [PSUBS-MAILIST] Terminating a conical
  transition
  To: personal_submersibles at psubs.org
  Received: Sunday, May 4, 2014, 8:32
AM

  Joe,

  Consider using an elliptical head back
there, for
  starters. You aren't
building for much depth here, so
  the
K-350 size will be fine (.375" ish). The ellipses
  are cheaper, do the same job, and give
you a touch more
  inside
room. Then I would have
  a cone rolled
  with a short flange on
the major diameter, maybe a couple
  of
  inches, to match the hull OD.

  The Nekton
cone-to-dome caused a
  pinch point
that was always a hassle to clean and paint,
  and
  ultimately left
some pitting in the pressure hull that had
  to
  be
weld-repaired. A short cylinder on the sheet metal
  would give you a little more room under
there to sandblast
  and paint during
assembly and later for overhauls. I would
  say for maintenance a couple of
flush-mount, gasketed
  panels
  in the tank would serve you well.
Don't make them
  too
  ornery to remove or you
won't do it as often as you
  will
  wish you had.

  I'm wondering now about my own
  boat and using tanks like that. Is there
  anyone in the
  group

who can plug and chug a metacentric height on Nekton
tanks
  installed on a K-350? Assembly
would be so simple that
  way.
  And it would tow better, which is always
a good thing. The
  Nektons roll a bit,
but are reasonably stable. A K with
  the
  pods should have plenty of weight down
low. Hmm. Would it
  work? I'm
thinking yes. Anybody else have an opinion

on
  that?

  Vance

  -----Original
  Message-----

  From: Joe Perkel via
Personal_Submersibles
  <personal_submersibles at psubs.org>

  To:
personal_submersibles
  <personal_submersibles at psubs.org>

  Sent: Sun, May
4, 2014 12:28 am

  Subject: Re: [PSUBS-MAILIST] Terminating
a conical
  transition

  Vance,

  Rethinking that aft assembly to make it
all soft tanks aft
  of a hemi head ala
Nekton.

  If I
go weld-on to the head ala Nekton, how best to attach
  to the head to allow for periodic access
and maintenance?

  Joe

  Sent from Yahoo Mail for iPad 

  From:

             via
  Personal_Submersibles <personal_submersibles at psubs.org>;

  To:

          <personal_submersibles at psubs.org>;

  Subject:

         Re:
  [PSUBS-MAILIST] Terminating
  a conical transition     

Sent:

             Sat, May 3,
2014
  2:03:36 PM     

   Joe,

  It
  seems like an expensive and complex
assembly for what you
  get. Why not
close the aft segment in a simpler way and
  fair
  the stern to the
shape you prefer? A hemisphere with an
  extended shaft housing to put the prop
where you want it,
  for instance.

  Vance

  -----Original

Message-----

  From: Joe Perkel via
Personal_Submersibles <personal_submersibles at psubs.org>

  To: Personal Submersibles General
Discussion <personal_submersibles at psubs.org>

  Sent: Sat, May 3, 2014 8:17 am

  Subject: Re: [PSUBS-MAILIST] Terminating
a conical
  transition

  Sean,

  Yes,
  a bolted
flange with O ring.

  I've
  attached an image of what's on my
mind. This hull is
  36" OD,
cylinder length is 120". Anything bigger
  in diameter, simply gets way to big and
bulky for
  handling.

  I'm
  thinking at this size, I must bolt at
least two hull
  sections together for
outfitting and maintenance, and the

cones can be un-stiffened or perhaps only at the
  joints.

  Joe

     On
Friday, May
  2, 2014 9:50 PM, Sean T.
Stevenson via
  Personal_Submersibles
  <personal_submersibles at psubs.org>
  wrote:

  Each cone
section in that case is considered

alone, so if you were using stiffeners, you would need a
  heavy stiffener at every joint.
Depending on the size, it
  may be
simpler to use unstiffened geometry for such an

  assembly.

  The rules do not address bolting
pressure
  hull sections together, but
I don't see why you
  couldn't,
provided you meet the requirements in terms

of
  the stress analysis under the
maximum combined loading
  conditions,
which are prescribed in the ABS rules.
  Might
  require
some FEA to be sure. You're thinking an O-ring
  groove seal? Or other arrangement? 
I think an ASME
  code compliant flange
would be a good place to start, but
  I
  would make sure that the cross-sectional
area of each half
  of the flange
considered individually met the requirements
  of
  a heavy stiffener per ABS, at a minimum material
  location
  (bolt hole). I
would also be inclined to use SuperBolts

for
  the connection. 

  http://www.nord-lock.com/superbolt/multi-jackbolt-tensioners/

  Sean

  On May 2, 2014
6:03:21
  PM MDT, Joe Perkel via
Personal_Submersibles <personal_submersibles at psubs.org>

  wrote:
  Sean,

  Would the heavy stiffener rule apply
equally to several
  cone
  segments stepping down at different
angles?

  Also, do ASME
pipe flange specifications translate equally
  to bolted
  pressure hull sections? Have I missed a section
  somewhere on bolted cylindrical
sections?

  Very helpful
Sean thank you!

  Joe

  Sent from Yahoo Mail for iPad 

  From:

         Sean T. Stevenson
  via

Personal_Submersibles <personal_submersibles at psubs.org>; 

           To:

           Personal
  Submersibles General

Discussion <personal_submersibles at psubs.org>; 

Subject:

             Re:
  [PSUBS-MAILIST] Terminating
  a conical transition     

  Sent:

         Fri, May 2, 2014
  11:45:11 PM    

  2:1
semi-elliptical heads are usually

fabricated with some
  length of straight flange (tangential
  cylindrical section) beyond the axis of
the ellipse.
  Hemispherical heads may
or may not have a straight flange

section, but in either case are
  permissible to use
  adjacent
  to conical sections, provided all other
requirements are
  met. For stiffened
cones, you must have stiffeners meeting
  the "heavy stiffener" criteria
at both ends, as
  close as practicable
to the cone-to-cylinder and

cone-to-head transitions. For unstiffened cones, the
  length
  L_c used in
overall buckling calculations must be the

total
  length between the next heavy
stiffener to either side of
  the
entire compartment length, or between the 40% of head
  depth points if otherwise
  unbounded.  Cone to head
  welds are done in the same manner as
cone to cylinder
  welds,
  and if your

    head is supplied w!
    ith a
  flange, it is the same

  thing.

  Sean

  On May 2, 2014 2:48:52
  PM MDT, Joe Perkel via
Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:

  I have
  spotted the ABS diagrams and
specifications for
  re-enforcement and
butt welds at conical to cylinder

transitions. I am somewhat unclear however as to
  terminating

  at the head.

  For
  example, the
diagrams in the 2014 ABS underwater vehicles
  and hyperbaric chamber publication shows
conical
  transitions

either bordered by a
  cylinder at
either end, or simply
  open
  at the small end???

    I want to terminate the small end of a
conical
  transition

directly to a small diameter hemi-head without another
  straight section, but I am unclear
as to whether or
  not

that is acceptable
    in practice.

  Joe

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