Re: Ballast Bladders

[Ray Keefer <Ray.Keefer@eng.Sun.COM>]

Hi Martin,

> Is anyone using soft external ballast bladders for emergency ascent or
> surface  freeboard?

Yes. I always thought of using some kind of bladder or lift bag as an
emergancy bouyancy device. I would use soft ballast tanks for regular 
usage. But if they get damaged like in a collision I would like to open a
valve and pop open the emergancy bouyancy bags.

> Unfortunately, there are some other problems,like containment of the
> inflated bladder,  possible bursting as you ascend, volume of blowing air,
> reliability etc.
> 

I would put them in flat boxes on the upper hull. The boxes would protect
the bags from wear and tear but would open up to let the bag out.

The air pipe would be  located inside the bag with possible a length of
flexible tubing. In any cases the opening of the bag would be centered above
the air pipe. The bottom of the bag would be open. So fill it up at depth and
as we ascend the expanding air will just leak out the bottom.

> Any comments?

Always. :)

Regards,
Ray