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Re: [PSUBS-MAILIST] Damage stability & ballast tanks at an angle




Alec,

Whether the sub goes vertical is going to depend upon where the center of gravity ends up after flooding and any shifting of equipment that might occur (jimk makes a good point here). Think of the flooding as not adding weight but reducing buoyancy and changing the center of gravity. Assuming you weighed enough and had some weights inside for trim that could be moved you could potentially move the center of gravity to balance the sub even if the forward compartment had flooded. Realistically that forward compartment would have to be a rather small volume to balance it out this way, but theoretically it would work.

The soft ballast tanks are definitely a problem if the sub tilts to the point that you lose buoyancy from them, however you always have your emergency drop weight which you can let go of. The sub should be configured such that dropping the emergency weights will allow the sub to surface even if the soft ballast tanks are flooded. Whether it will do the same with a compartment flooded depends on whether that situation was planned for.

Jon


On 4/17/2012 8:53 PM, Alex wrote:
I've been thinking about what happens if you have a water tight
bulk head in the middle and the forward or aft compartment floods. Or possibly
with 3 compartments with forward or aft flooded.

Does the submarine go almost vertical? And the most important part of this is
what happens to the external soft ballast tanks. If the tank has a bottom vent
in the middle and it becomes vertical, it will only fill up half way with air
before it bubbles out.

Worst case scenario: Let's say you have a sub with huge ballast tanks on the
bow and stern that can surface even if it is fully flooded inside. Let's say
that the forward ballast tank is damaged and the forward compartment is
flooded. The unflooded aft compartment and stern ballast tank should be enough
to surface. But will the stern ballast tank work with the bow pointed way down?

Alex




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