Dive and Discover : Daily Updates

Today’s sunrise was a study in grays and peach colors, and streaks of white clouds high in the sky. Our gazing at the dawn was interrupted as we pulled the Towed Camera Sled up over the side of RV Atlantis at 0630 hours. When it was on deck we noticed there was a problem - one of the battery boxes had its rubber bladder bulging out like a balloon ready to burst! Each battery box contains oil, not too much different from cooking oil, which protects the electrical connections and the gel in the battery from the harmful effects of seawater. It turns out that some seawater (almost 2 gallons!) had seeped into the casing, forming an oil-water emulsion, or what some chemists call a “mousse” (like the texture of chocolate mousse - but you can’t eat this stuff!).

An emulsion is created when two immiscible (not able to be mixed) liquids are forced together, causing one of the liquids to break up into tiny droplets held in suspension within the other liquid. Some common emulsions you use every day include oil and vinegar salad dressing, milk, and mayonnaise. The bladder was bulging because the seawater had reacted with the gel of the battery and made gas. Greg and Dan puzzled over whether this could have been the reason why the Sled was not taking pictures for more than 7 hours on some of the last tows. We’ll find out tonight. The “Night Owl” Towed Camera Team worked quickly today to replace the battery with a spare and the Sled will go down again tonight, as planned, for Tow #7.

Today’s dive included a special event. It will be Dave Olds’ last dive in Alvin. Dave has been a very valued member of the at-sea Alvin group, and one of the key electrical techs for the sub for more than 5 years. He took the PIT (Pilot in Training) seat and piloted the sub expertly for the entire dive. Bruce Strickrott was the official pilot, and Dana Yoerger was in charge of the geophysical data collection.

While the science goes on every day, and Alvin is sent to the seafloor to carryout experiments, the crew of RV Atlantis take care of our floating “home” away from home. Today we saw one example of how important it is to do routine maintenance and checking of all the complex systems that keep Atlantis running. Over the past few weeks, Chief Engineer Kevin Fisk has been monitoring some noise made by the port aft thruster. Basically, that is the big “eggbeater” or Z-drive that propels the boat forward.

Unlike many ships that use a conventional rudder to steer, the two rear propeller thrusters on the Atlantis can turn a full 360 degrees, allowing them to control the ship’s direction instead of a rudder. Combined with the bow thruster, which can be used to effectively ’push’ the ship from side-to-side, Atlantis is able to finely tune its position - very important for all of the geophysical survey work done on board, as well as for the delicate launch and recovery operations of deep sea vehicles like Alvin, ROV Jason and ABE.

Kevin and his engine room crew have been keeping track of the strange noises that the equipment has been making and taking measurements. They found out today that they need to keep the port thruster off, so that it does not get damaged by further use until it can be opened up and inspected in port, and any worn parts replaced. This means that the ship can only go about 8 knots using the starboard thruster.

Captain Silva spoke with the engineers and support staff at the Marine Operations Office at Woods Hole Oceanographic Institution and they decided that instead of heading up to San Diego, California, where the cruise was supposed to end on February 11, we will be heading back to where we started this leg of the journey - Manzanillo, Mexico. We hope to arrive in the middle of the day on February 9. After letting the science party off, the ship will continue to head North to San Diego. They expect to arrive there on February 17.

After Alvin got on deck and the observers and pilot got out of the sphere, the Alvin crew decided to celebrate Dave’s last dive by sending him back down to the bottom... of the pool! We'll miss you, Dave! And Best of Luck in Your Future Work!

Dive Summary
On Bottom: 0940 hours
Off Bottom: 1446 hours
Maximum Depth: 2555 meters

Today’s dive continued “mowing the lawn” as marine geologists and geophysicists call doing grid surveys of the type that Alvin is doing here on the East Pacific Rise crest. Dana’s doppler sonar continues to provide excellent relative navigation information and the acoustic transponder navigation is also providing very good absolute position information. The two data sets combined will make the interpretation of the geophysical data much easier and help improve our ability to make geological and geophysical interpretations. At the end of the dive they were reminded by Pat Hickey, in Top Lab, that they had passed one of the way points where they were supposed to turn North. Dana called up saying that they were seeing great geology, and even a large field of extinct hydrothermal chimneys, so they decided to keep going another few hundred meters before turning. When Dan heard this he was excited because no one had ever found any evidence of past hydrothermal activity in this area. Tomorrow, Dan and Del will start near the old chimneys with BLee as their pilot and carry out the last geophysical dive of the cruise.