Re: rusty tanks (was: Trojan)

[VBra676539@aol.com]

Jon,
	You thrill seeker you!
	The problem with blowing the trim tank is that you commit yourself 
without any recourse.  You're going up, and that's all there is to it.  And 
then the ski boat moves over and ....   Of course from 40 feet you already 
know things are clear and it figures to be the equivelant of our hold point.  
We always made a bubble for the surface to find or, at night, let them find 
our lights, waiting at depth until we were cleared to surface.  Then it was 
blow and go.
	Working the North Sea we were doing 8-hours a day give or take in the 
water and sometimes got a little loony.  Okay, maybe we were loony all the 
time.  For instance: there was a sort of informal contest to see if anyone 
could blow for the surface hard enough from our hold point at 50-60 feet to 
get the entire forward viewport clear of the water.  Perry MBTs are nearly 
1000 pound displacement for the saddle tanks so if you could glow hard enough 
.... well, you get the idea.  The viewports were 40" OD and completely below 
the water line, so it was pretty near impossible to get the nose up steep 
enough. I only did it once but it was a very rough day and we kind of surfed 
out of the front of a biggish wave on the way. Jean-Francois Durand was not 
overly amused by all this foolishness with his half million dollar (and up) 
submersibles as you might well imagine, and put a stop to it.
Vance
In a message dated 5/7/99 3:59:30 AM, shawl@torchlake.com writes:

<<Hi Vance and all,
I like a guy with a sense of humor!
How I surface from the great depth of 40' (in my 5/16" thick propane tank 
sub), is
to just blow the trim tank and wait till I get to the surface then blow the 
MBT.
Nothing gets out of control and I don't waste any air. I did have some fun 
doing a
fast surface with a fast full blow from 40 or so feet. The sub was moving up 
so
fast it started making a buzzing sound.
It took a while to figure out what it was. It was the 3/4 " dia by 3' long
magnesium anode rods that are located about a 1/4" from the bumpers. When the
water flows down past them they start to vibrate till they hit the bumper. 
It's
like a built in alarm for over speed surfacing. Only made it into low orbit 
for
about a 1/4 second, then splashdown right into the same hole in the water it 
came
out of. Weeeeee...   Didn't have to call NASA. :-)
Jon Shawl


VBra676539@aol.com wrote:

>       Ascent rates are usually held at 60 feet per minute or thereabouts
> (easy to do as bubbles handily rise at about that rate and you just follow
> them up) unless you are coming up from pretty deep in which case nearly 
twice
> that is possible.  Regardless, you will slow down in shallower water because
> things can get out of hand very quickly indeed if you do not. The volume of
> air in your MBTs will double every once in a while enroute.  This gets to be
> a very important thing to remember as you near the surface.  Volume doubles
> at 60 from 120--again at 30 from 60--again at 15 from .... well, you'll be
> skyrocketing and out of control by then and Katie-bar-the-door because 
you're
> coming through!!!!!  The clever psubber will of course remember that the
> shallower he gets (during ascent) the bigger his MBT bubbles get and the
> faster he goes the faster the bubbles get bigger and the faster the bubbles
> get bigger the faster the sub goes and pretty soon he can't dump enough
> through the vents to slow down and there's nothing left but that cabin
> cruiser between him and a space shuttle rescue as he's likely to be in low
> orbit before the thing slows down.
>         In point of fact, you will be pretty steadily venting squirts of air
> from the tanks as you rise to maintain that 60 feet per and watching upward
> pretty carefully for that cabin cruiser.  Then you can stop at 50 feet or so
> and let the bubbles go past and make a nice surface marker so your support
> crew can see you and make sure the area is clear.  Much better than
> contracting NASA for a rescue.
>



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Date: Thu, 06 May 1999 23:00:20 -0400
From: shawl@torchlake.com (Jonathan Shawl)
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Subject: Re: rusty tanks (was: Trojan)
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