I believe ABS requires 125% without unexpected deformation and collapse levels calculated at a minimum of X2. Testing is done with strain gauges to 110% annualy. I wouldn't be happy with decimal points in FRONT of my safety margins.
Frank,
The hull calculator works good, but doesn't take into account ribbing on tank heads. The best you could do with the existing calculator is determine the max depth for a non-strengthened tank head. If the majority of your diving is going to be in 150 feet of water, you might find that the tank heads without ribbing will support that depth, resulting in a lot less manufacturing work for you.
I can never remember the exact dimensions of your tank heads, but I seem to recall 84 inch diameter and 3/8 thickness. The hull calculator shows me that with a tank head depth of 23.25 inches and a skirt of 2 inches, your un-ribbed tank heads will buckle at around 362 feet. With a .5 safety margin you could do 181 feet, and with a .67 safety margin you could do 242 feet.
I'd be interested in any ribbing data or specs you have for ellipsoidal heads.
Jon
ShellyDalg@aol.com wrote:
> Hi Jay. Although the maximum depth I'm aiming for is 600 fsw, I expect > to stay above 300, with MOST dives maxing at 150.
> I will be testing ( unmanned ) to 500 feet and it calcs out for a > crush depth at about 900 and change.
> This is partly an educated guess though because I never got the hull > calculator program to work so I had an old engineer friend work up the > numbers. That's what he came up with and frankly, I'm no math whiz.
> I haven't installed the stiffeners yet either so the deep water > testing will be after it's had a few shallow dives on it.
> I'll just be careful to stay in water that doesn't go that deep until > I get better information. The stiffener design for a saucer is a > little more complex than a straight tube. It resembles the ribs on a > pumpkin with extra supports near the windows, gussets under the hatch > flange, and behind the window flange bases.
> On the scuba tanks, I'm piping the tanks directly into a HP manifold > with regulators on the outlets.
> The tanks get pumped to 2400 psi but that drops as the air is used. > Here too I'm relying on a friend who as a pipe fitter, has a lot of > experience with high pressure gas systems.
> Frank D. >
> ------------------------------------------------------------------------
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