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Daily Updates: January
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partly cloudy weather

Latitude: 18deg 38’ 53” N
Longitude: 104deg 24’ 42” W
Wind Direction: NW
Wind Speed: 14.5 Knots
Sea State 2
Swell(s) Height: 1 Foot
Sea Temperature: 83°F (28.6°C)
Barometric Pressure: 1014.3 MB
Visibility: 10 Nautical Miles

what's to eat today?

French toast
Canadian bacon
Scrambled eggs
Saut�ed potatoes
Assorted fruits
Multigrain oatmeal

Salad bar
Tater tots
Chicken with rice soup
Tuna Sandwiches
Grilled reuben sandwiches
Fried rice

Salad bar
Halibut with ginger sauce
London broil with onions and mushrooms
Half baked potato
White rice
Cauliflower with cheese sauce
Black and white cherries

Transit to Dive Site
January 28, 2000
By Dr. Dan Fornari

Daybreak saw the RV Atlantis steaming at almost 13 knots through near glassy seas, scattering flying fish by the dozens as it headed to the dive site on a course of 185°. All the scientists on board are getting used to the routine of life at sea, learning when meals are served, and getting acquainted with the ship’s crew. Patrick Hennessy has the trolling lines out but so far no fish has hit the lines, probably because we are going so fast. Interestingly, we’ve heard that the fishing out in this area of the Pacific has not been very good the past few years because of El Nino. We’ll be able to tell first hand when we get to the dive site and the fishermen among us break out their rods and reels!

Today, graduate students, Greg Kurras, Jenny Engels and Del Bohnenstiehl worked hard at preparing the Towed Camera Sled for the night-time surveys it will do. This camera sled is a much simpler version of the Argo towed mapping system operated by the Woods Hole Oceanographic Institution for many scientists [Click here to learn more about ARGO]. Argo is able to send up four video signals, sonar data, and loads of other types of information to scientists on board a ship so they can look at, and map the seafloor as they are driving over it. It can even steer around a bit using its 2 thrusters.

The Towed Camera, on the other hand, has affectionately been called a “Dope on a Rope” because it does not have any of the “smart” features of the fiber optic based Argo. The Towed Camera Sled does a good job though by collecting photographs of the seafloor that scientists can use for their research. It has a deep sea digital camera made by Benthos, Inc. of North Falmouth, MA, a well known manufacturer of deep ocean cameras and equipment. Dan Fornari has been working with Bill Hersey , an engineer at Benthos to develop this camera over the past few years. This camera takes 2300 black & white digital pictures on each lowering to the seafloor and stores them on a 4 Gigabyte (a Gigabyte is 4 billion bytes of information!) hard drive in the computer that is built into the system.

The camera uses 2 high-power strobes (600 watt/sec) for lighting. The sled is towed about 7 meters (23 feet) above the seafloor and scientists onboard Atlantis are able to tell how high it is above the rocky bottom by using a pinger. The pinger makes a sound that is bounced off the seafloor and also travels directly to the ship. The two sound pulses (the direct one and the bounced one) are received by a hydrophone, an underwater listening device on the hull of the ship, and fed into an amplifier to make a record on a screen. The separation between the two pulses tells us how far off the ocean floor the camera is. Sometimes, if the seafloor is very rough it is hard to keep from hitting. That’s why the Camera Sled is so sturdy! After the tow, when the camera is back on board Atlantis, the students will transfer the images from the camera to computer disks and then analyze them. We’ll hear a lot more about the discoveries that the Towed Camera Sled will make in the days to come. We are hoping to do a first test lowering tomorrow night.

Briefing the scientists who will be diving on this cruise continued today as the Alvin crew kept doing their routine maintenance of the submarine as well as checking all the wiring and operation of the gravimeter, magnetometer and another Benthos digital camera (this one takes color photographs) that will be used during the dives. One important task that the crew has to do when a new science party comes on board and installs new equipment is making sure that there are no grounds in the electrical systems (Read more about the electrical system in Alvin)

Because Alvin operates on batteries, and because it dives in the ocean where the salt water easily conducts electricity, they have to be very careful about how the electricity flows in all the equipment that is operated in the sub. so that it is safe and not wasted. It takes a lot of time, patience, and knowledge to do this correctly. Tomorrow we plan to launch transponders in the morning, and survey-in their positions so that we have good navigation for Alvin when it dives on Sunday.

Keeping The “Big O“ Out of Alvin
By BLee Williams
BLee Williams holding one of Alvin's penetrators. These penetrators are located around the viewports and are where wires from outside of Alvin's sphere come inside the sub.
Submarine are often called “electric boats” because they need lights and power to see and move, computers to log data, and sensors to measure temperature and pressure. Add to that the manipulation capabilities and the needs of the scientific equipment that Alvin uses, and you can see why Alvin needs electricity to operate.

Understanding how electricity can be safely used in the “Big O”, as submariners sometimes call the ocean, is one of the first and most important lessons a new submariner learns. Seawater is able to conduct electricity very easily. Very pure water will not conduct electricity, but if you add salt to it, then electricity will pass through it because of the dissolved salt. The electrical energy to run Alvin and all its tools is stored in big batteries made up from lots of high-power golf cart batteries (see the Interview with BLee Williams - Alvin’s chief electrician and the person responsible for its batteries). It is very important that the energy stored in these batteries is not allowed to ’leak’ out of Alvin. Apart from wasting precious power and not being able to complete all the science planned for a dive, leaking power causes damage to equipment.

Electricians call leaking power a “ground”. When a piece of equipment becomes grounded, the electricity no longer flows through it correctly. Instead of staying in the wires, electricity gets out where the equipment is plugged in or, in the case of equipment on Alvin, into the pressure housing (the titanium metal case that protects the wires and components from the pressure in the deep ocean). These grounds allow the electrons holding together the atoms of metal in the electrical wires to “float” away into the ocean. If the ground is bad enough, or is left uncorrected, the metal actually begins to disappear as the bonds holding the atoms together are removed. This is called “corrosion”. Pretty soon, the wire disappears and electrons can no longer move along it. This could lead to electrical connectors failing and could let seawater into pressure housings or even the Alvin personnel sphere.

A close-up view of one of Alvin's penetrators.
Grounded equipment does not work properly, so sensitive instruments that rely on electricity from Alvin’s batteries need that power to be good, or “clean” as electricians call it. Alvin’s electrical team (ETeam) is primarily responsible for the sub’s electrical systems and testing for grounds on all its permanent equipment, as well as additional equipment that different scientists bring out to do their experiments. The ETeam inspects Alvin’s electrical system for grounds before and after every dive. During the dives, the pilots check for grounds frequently. Equipment that becomes grounded is never operated. Even a “little” ground on a piece of electronics is not “good enough”; it is either not grounded or it is not used.

I tell new members of the Alvin Group: “It’s nice to love the sea, but a healthy respect for the awesome power of the water is what will keep you alive”. Keeping track of grounds and where electricity is flowing in Alvin is important when working in the “Big O”.