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Myles,
I don't drill the rings. What I wrote is
CLAMPING TO the rings. I have seen holes drilled in framing rings but I'd
rather not compromise them either, so I fashioned clamps that either clamp to
one ring or clamp between two adjacent rings as need be. But, all
my PREPAINTING mountings were made by welding to the hull itself.
Some builders go through the trouble of making
their farming rings a bit over sized and have them machined true round, then fit
them to the hull. I built mine to exact size in a pretty accurate steel
jig. Welding can warp them into a pretzel if not done with some fore
thought. You need to preheat, then weld in separate stitches ,mine
were about four or five inches long at different locations on the ring to
minimize warping.
The forces of weld shrinking as it cools can be
used to your advantage when welding the rings into the hull. There, I
skipped around stitching them in also. My rings came off the jig with
maybe 1/16 to 1/8 out of roundness. When installing them in the hull, I
used this out of roundness to compensate for the out of roundness of the tube by
orienting the rings so the two forces counteracted themselves. There were
many times I need to jack the hull inside, from side to side, as the frames
were being installed also, but the result is my hull is no more then 1/16 out of
round.
There is a frame in the location of the conning
tower but part of it is removed. The framing keeps the hull plate from
deviating from true roundness so any place there is nothing to support the hull
plate is potentially a place for the hull to flatten out just enough for a
catastrophic failure by implosion. You need to keep the hull round
and hold it there with framing. The conning tower reinforcement ring
intersects the one frame. The terminated ends of that frame, must be
welded securely, and maybe even reinforced, to the conning tower reinforcement
ring to carry the forces through the intersection of these two pieces. The
result is, even though the hull in compromised by the hole cut in for the
conning tower, it isn't compromised in it's structural integrity in that
location.
You should be able to see some of what your
questioning in the pics of my Persistence and also Johns Lake Diver.
If you want to see more, contact me off list and
I'll attach you a pic or two.
Dan H.
----- Original Message -----
Sent: Wednesday, November 09, 2005 11:22
PM
Subject: Re: [PSUBS-MAILIST] Inner /
Outer support ribs.
Dan,
The point I never considered was
using the rings to force the hull into roundness. I can definately see
where this would be easier when putting them on the inside as they could be
pounded / hammered / tapped into place, spot welded, and then secured when all
was well. That answers another question in that the rings are to be pre
made and not welded onto the pressure hull when building them. In that
way, the roundness of the rings could be made true before installing. As
for attaching things to the rings inside the hull, is it safe to drill 1/4"
holes for bolts or is that comprimising the integretity of the ring too much
? ...or would welding mounting brackets to the rings and then drilling
the holes be preferable ?
On the K350, does the design just
eliminate the ring where the tower is, the tower collar providing the strength
in that area ?
Thanks for making my mind up for me
Dan.
Myles.
----- Original Message -----
Sent: Wednesday, November 09, 2005 9:10
PM
Subject: Re: [PSUBS-MAILIST] Inner /
Outer support ribs.
Myles,
A K-350 has ribs spaced 12 inches apart, and at
the ends where the hull tube meets the end caps, they are 10 inches apart
leaving two inches of hull tube sticking past the last frames to weld
the end caps to.
True, the frame would be easier to apply
to the outside of the hull, for convenience of working, but it's easier to
spring the hull into better roundness when working from the inside. No
rolled tube is perfect round. You have to work it as your
installing the framing.
Ribs on the outside give you more places for
corrosion to attack, but do increase the inside room. Ribs on the
inside cramp the space in the sub, but are a convenient place to clamp
things that you want to add later on, without welding on the finished sub
hull.
Dan H.
----- Original Message -----
Sent: Wednesday, November 09, 2005
6:11 PM
Subject: [PSUBS-MAILIST] Inner /
Outer support ribs.
I understand that support ribs offer the same
strength increase whether they are on the inside or outside of the
pressure hull. As I am planning on adding fairing, I am also
considering puting the ribs on the outside to free up interior
space. Is this a good idea ? In other words, is it easier to
install the ribs when they are on the outside ? Are the ribs
pre-made and then welded on or built right onto the pressure
hull ? I can't seem to figure out the ribs, how they are made, and
the best way to install them. My pressure hull is of a similar
design as the K350 36" x 1/4 " x 8'. I am considering a rib
spacing of 18".
Myles.
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