Our last science cruise to the Samoan Passage, we spent a lot of time sending instruments to 5,200 meters. The pressure at these depths is intense.
Consider this: A few feet below the surface of the ocean the pressure is about 14 pounds per square inch (p.s.i). Where I sent this Styrofoam cup to the pressure was 7,080 p.s.i. at just over 4,600 meters deep or 15,180 feet.
The cup on the left was made as a present for my daughter’s 18th birthday. It started as a normal cup like the one on the right.
The pressure affects the science operations as well. The moorings can use floats made of dense foam. The problem is they are very expensive. The more common method is to use a series of glass floats encased in a hard plastic shell called a hardhat. Each glass float provides about 50 lbs. of lift and is rated to 6,000 meters deep. They are set up in series like this:
Some moorings may use several series in different locations on the mooring line, for example to keep an instrument in the correct position. Sometimes, even though the deepest we went was 5,200 meters, the floats implode from the pressure. This is what they look like when they implode:
The remnants of the glass float inside the hardhat looks like a large chunk of salt:
Sometimes we get little shards of plastic back impregnated in the glass.
Pretty cool to witness. That is all for today’s lesson. Carry on.