Re: Visibilty / Safty or Safty / Visibilty ?

[Rick Lucertini <empiricus@sprint.ca>]

Jonathan Shawl wrote:

Phil Nuytten wrote:

>  [snip] The point is, you can make a sub out of damn near anything that is
> impermeable
> to water . .it's just that some materials and shapes are more efficient that
> others. Sub design, like life, is a series of trade-offs and compromises.

I agree with that totally. My first sub was made from an aluminum wing tang
(hull). one half of a 275 gallon oil tank, the end of a water tank (hatch), the
hatch gasket came of a washing machine tub, and 4- 100 lb size propane tanks
(ballast tanks), and it worked to 12'. Then I tested it later and it crushed at
15'.
[snip]

> How deep are they going in the successful fiberglass
> dry 1 Atm, subs?
> Do they know the crush depth? Are they operating them close to crush
> depth and
> don't even know it?
Actually, they do.  The individuals Phil is referring to are seasoned
pro's.
> Is there any way to reliably predict the crush depth
> of the one off subs you
> are talking about?
By following your suggestion of blowing a hull first.
> I can't think of any tradeoffs that would make it
> worth while to build a flat
> sided pressure vessel or to make one out of anything other than time
> proven,
> cheep, strong, steel.
There are several reasons, not all of them technically satisfactory. 
Sometimes, a decision can be a "just because".
I don't work much with metal.  But, I enjoy wood.  So, I
read the following with lust in my heart.  Why?  Because. 
Does steel make more sense?  Probably.  But, using a plexi dome
for hi-vis, on top of two plywood pontoons is, to me, a fantastic tradeoff. 
Like Phil's saying, UNDERSTAND THE PARAMETERS.  That's the qualifier
here.

Read the following and weep . . .

1st of 2:  '"Hikino"  (US Navy), 56 in. by 0.75 in. thick acrylic sphere, test depth 30 ft.  Pardon me?  3/4 in. plexi?  Not that thick.  But, it worked.  Another hull may have been made at 1/4 in. thickness.  Operating depth of that one was 20 ft.

2nd of 2:  "Submanaut".  Made of 4 in. thick PLYWOOD "donuts", covered with 0.75 in. of epoxied glass fibre.  TESTED to 350 ft., operating depth 200 ft.  Crush depth calculated at 1,000 ft.  4 hrs. at 1 kt

> Maybe someone can enlighten me? I like to think I
> have a open mind. But I will
> always stick to safety first over all other thinking.
That goes without saying.  But, I believe we all are really agreeing
on safety.  It's the parameters that we're a little fuzzy on.
> After all, what is the
> point in making a unsafe sub, or one that is only safe to, lets say
> 30'? Might
> as well go diving.
Well, the experience of sitting in a sub with water over your head is quite
different from diving.  I remember the first time I used hookah. 
Unlimited air time.  Spent four hours on one dive!  Or what about
the first time you wore a hi-vis diving mask?  Could always have said
that they were too hi-volume, hard to clear, too buoyant, too many windows,
etc.  But, damn, you could sure see a lot more!
> I think we are agreeing. If not, how long before
> we get to the part where
> people start beating the dead horsie? What type of club or whip do
> I buy?  Just
> asking, I'm new here. ;-)
Um, I think you've got an intuitive sense of survival here, Jon. 
It's just about now we start wondering how far THIS thread's gonna go.           
:-)

Rick
 
 
 

--
Rick Lucertini
empiricus@sprint.ca
(Vancouver, Canada)

"Most people die with their dreams still inside them."