[PSUBS-MAILIST] Newbee to psubs...

["John R. Farrington" <jrf@austin.ibm.com>]

Hi all,

Just wanted to take a few moments to introduce myself.
I've been lurking on the list for a little while, and
interested in psubs for quite a number of years now.

I'd exchanged some mail with a guy named Matt Hunsaker
about 6 years ago and he'd given me some interesting
info on a sub of his, a Sportsman 300.  That kinda
got me interested in psubs, but I pretty much shelved
the idea until now.

I've been digging through the archives to start becoming
more familiar with psubs, and to start getting a grasp
on what is involved in building one.

I'm in contact with Vance concerning the Kittredge plans
and now have a few more general questions that I thought
I'd pose to the group.


With respect to psub certification:

  It appears that psub certification is very valuable.
  Any idea if most psubs that are out there are actually
  certified, or do most people just do away with having
  them certified?

  I do have welding experience, but have no license or
  welding certification of that sort.  If I do my own
  welding on the pressure hull, is the hull still
  certifyable if it passes the appropriate depth tests?

  The sub that I'd be building would likely be of the
  Kittredge variety, I believe rated to a depth of 250
  feet.  This means it should be tested to 500 feet or so.
  I live in Austin TX, which doesn't have any 500 foot
  deep lakes around.  When others pressure test their
  subs, do they typically trailer them down to the ocean,
  hire a boat with some sort of crane/winch mechanism,
  haul the sub into deep water, then do a number of
  plunges with the sub to the test depth?
  (BTW, if anyone owns a sub, and lives in central TX,
   I'd be interested in seeing the sub in person)


The sub that I build would probably do 99% of its
dives in the local lakes, which usually have a visibility
of 15-20 feet, or less.  Sometimes 5 feet or less in some
areas.  Because of the limited visibility, I've got big
concerns about getting the sub tangled in someone's old
anchor line, or whatever may be lurking on the bottom.

Has anyone out there had any serious incidents involving
entanglement?  Ever had to abandon because of entanglement?

I'd like to be able to get out of the sub, clear the
entanglement, and get back in, without having to flood
the sub.  Anybody have a sub with a hatch on the bottom
as well as on the top?  ie: Raise the air pressure in
the sub to ambient, exit with scuba gear, clear the
entanglement, climb back in, head to surface, bleeding
off extra pressure on ascent. (keeping in mind all 
nitrogen-related issues)

A K-250 has an approx. volume of 40 cubic ft from what
I can tell.  So one full scuba tank would get you
an additional 2 atm inside the sub, which is about
65ft of water.  I'd need 2 full tanks to be able to
exit the sub at 125 feet, three would get me over
180ft, (max lake depth is around 160), but at that
depth, I don't think I'd really have the time
(decompression-wise), to fill the sub, get out, clear
an entanglement, get back in, and get the sub to
shallow water before taking on too much nitrogen.

(sorry for being long-winded)  ;-)

But maybe at 50ft I could get out and back in.

The idea is to save the sub, without flooding it.
Or, are my efforts better spent building the sub such
that flooding it damages as little as possible?

I'm still trying to decide if building one of these
would be worth it, knowing all of the risks, as well
as knowing that my primary dive opportunities will
just be in a lake.

Sure sounds like fun though!

Thanks for any advice.

-John Farrington