Oh Suzanne,

I envy you this! In an alternate universe, I would be the sub pilot.

Now take note on a few things, will you? If I can't be there, I need you to be my eyes and ears.

Do you have to pop your ears going down in the submersible? As a diver, we have to.

Can you feel the pressure mount as you descend? Is the internal air pressure built up to counter the ocean pressure so the craft doesn't implode?

Does this thing have a sea door, where a diver could exit for outside work and come back in?

Do the folks have to breathe heliox and talk like Donald Duck so they don't suffer from the bends upon surfacing?

Do you have to make decompression stops on the way up?

These are things I have ALWAYS wanted to know. It's hard to write undersea science fiction with these annoying gaps in my knowledge -- but also very hard to find answers to these esoteric things.

I hope you read this before you descend!

Bon voyage!

12:28:56 a.m. on June 6, 2006
HENRY STEPHENS | 06.06.06 - 12:33 am | # |Report as offensive

Some Answers to Henry's questions from someone who works at Harbor Branch. For more information about this cruise , the ship and the sub, go to http://www.hboi.edu and http://www.at-sea.org to follow this cruise day by day.

No, unlike a diver, inside the sub you don't have to pop your ears to equalize pressure. The pressure inside the sub remains at 1 atmosphere, whether you are at the surface or at the sub's max depth of 3,000 ft. The vessel doesn't implode within this range because the pressure hulls are designed to handle pressures well in excess of 1,360 lbs per sq in, which is the pressure at 3,000 ft (keep in mind that at 1 atmosphere you have a mere 14 lbs per sq in. weighing down on you). To accomplish this, the sub has an aft compartment made of aluminum and a forward compartment made of plexiglass that is more than 5 inches thick.

The aft compartment was designed as a lock-out chamber and has a hatch mechanism that opens downward so that if the cabin were pressurized to the same pressure as the water outside, that water would not rise into the chamber. We no longer conduct lock-out dives because we have equipment and tools that can carry out the work that divers used to have to do. Using manipulator arms and other tools is safer and allows us to conduct work at much deeper depths.

In the sub, regular air is breathed, again because the occupants are not exposed to higher atmospheric pressure. There is consequently no risk of bends either, for that same reason, and no decompression stops are necessary on the way up.

I hope this answers your questions and do check out the web sites listed above.

Best,
Jan Petri
Harbor Branch

4:29:35 p.m. on June 6, 2006
JAN PETRI | 06.06.06 - 4:34 pm | # |Report as offensive