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PIT Phil Forte, filmmaker Mike deGruy, and pilot BLee Williams pose beforemaking Alvin dive #3500. |
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| 3,500 Dives to the Bottom |
Sunday, November 28th, 1999
Location: 9º 49.804' North, 104º 17.361' West
Dive # 3500
3,500 Dives to the Bottom
Today marked the 3,500th journey Alvin has made to the seafloor.
Named for its builder Allyn Vine, Alvin made its first dive in 1964 near Woods Hole, Massachusetts. Owned by the U.S. Navy and operated by Woods Hole Oceanographic Institution (WHOI), Alvin has been the workhorse of the deep-sea scientific community ever since. It has a depth rating of 4,500m (14,728ft) and can accommodate 3 people, including its pilot, in its 6-ft diameter titanium sphere. Its 35-year history has included 3 support vessels: Lulu, a catamaran named after Allyn Vine's mother; the 245-ft R/V Atlantis II, its mother ship from 1983 until 1997; and now the 274-ft R/V Atlantis.
Over the years, Alvin has been involved in a countless number of amazing expeditions, including the first-ever manned submersible dive to hydrothermal vents in the Eastern Pacific in 1979 and the discovery of cold-water hydrocarbon seeps in the Gulf of Mexico in 1984. Alvin was also the first submersible to dive on the most famous shipwreck of our time, the RMS Titanic. In addition, along with the French submersibles Cyana and Archimede, Alvin participated in Project FAMOUS (French-American Mid-Ocean Undersea Study), the first close-up study of the Mid-Atlantic Ridge.
Alvin has indeed had a colorful past, including an unintentional "trip" to the bottom in 1968. During a series of dives looking for whale outfalls, Alvin's support cables failed and the submersible slid into the water and sank to the bottom 5,000ft below where it spent almost a year waiting to be recovered. To find out how it was recovered, and for the complete history of Alvin, visit WHOI's web site.
What Does This All Mean?!
Scrubber scrubbing? UQC check was sat? Leaks, dumps, and grounds normal? As promised in the November 16th Expedition Log [LINK THIS TO THE NOVEMBER 16 LOG], pilot BLee Williams explains the conversation that takes place between Alvin, the Atlantis, and the Avon just before the submersible disappears beneath the surface.
Alvin is a team effort. It's not just the Alvin Group, but all of "Team Atlantis" that is required to operate the sub for a safe and successful dive. There are 17 pages of pre-dive checks performed on the sub, and the A-frame crane that lifts it, before the sub even gets wet each morning. Just prior to the launch Alvin's pilot carefully reviews these checklists before sealing the hatch, and verifies that each critical item has not been missed. Not properly completing the pre-dive checks endangers the sub, its occupants, and the objectives of the dive.
Even after the sub is launched the safety checks continue. As the sub enters the water, the pilot verifies that the circuits that drop the dive weights are still connected and have not been "shorted out" by seawater. Dropping these weights allows Alvin to surface, a highly desirable thing when the dive is completed. The circuits were checked on deck before the launch...but if the seas are rough, the sub's entry into the water can be rather abrupt. The pilot also checks the circuits that release the explosive bolts that connect various equipment to the sub. Releasing equipment from the sub isn't part of a normal dive; in fact it has never been done as far as I know. But ensuring that the pilot has the ability to "dump" things that may prevent the sub from surfacing is part of the safety blanket required to operate Alvin.
Once the dump circuits, including the weight droppers, have been checked, the pilot tells the swimmers to remove the science basket "safeties." These safeties are ropes that help support the weight of the science gear mounted on the front of Alvin as it is lifted off the deck and into the water. The swimmers remove the safeties so the pilot can drop the science basket if it becomes snagged or if a large rock falls into it during the dive. The basket is mounted on an assembly identical to the weight droppers, and it is checked for a proper connection after the sub is in the water; the swimmers stay clear of it until the pilot tells them that he has completed his checks. A dropped science basket would be a rapid one-way trip to the bottom for a swimmer caught on or under it.
Next the pilot checks the rest of the sub's electrical systems for grounds to the ocean. He checks his Leak Detector, which verifies that water has not leaked into any of the 25 different areas that it monitors. The pilot looks at the Nav (navigation) Box, checking to see that his tracking frequency is set. He checks his life support systems: the oxygen bleed and carbon dioxide "scrubber," a device that keeps carbon dioxide from reaching dangerously high levels, even though he started them only a few minutes before (you need air to breathe!). He talks on the underwater telephone, called a UQC in sub-speak, and gets an answer from an Alvin pilot back aboard the Atlantis who stands watch in "toplab." That pilot, called the Surface Controller, keeps track of where the sub is and talks to its pilot every half hour ensure all is well.
If all the previous checks were "sat" (short for satisfactory) the pilot instructs the swimmers to "turn on the light, open the valve." The light is the Submarine Identification Light, which would help the Atlantis find Alvin if it surfaced in the dark or in poor weather conditions. The valve is the Forward Main Ballast Tank Isolation Valve. With this valve open the pilot can let water into his ballast tanks when he is ready to dive. The resulting loss of buoyancy causes the sub to start sinking toward the bottom..
With all that done, he picks up his radio. "Atlantis, Alvin; the hatch is shut, the valve is open, the light is on, oxygen's on and the scrubber is scrubbing, tracking is on 12.5, the UQC check was sat, leaks, dumps, and grounds are normal. Request a launch altitude and permission to dive when the swimmers are clear." As I do this I look at each item as I speak, performing a final check before starting down. The Surface Controller initials each item on the Post Launch/ Pre-Dive Checklist as the pilot goes through them. He has determined the water depth (typically 2500 meters here at 9º North), and if all conditions are within the "operating envelope," the conditions required to make a dive, he replies "Alvin, Atlantis, your launch altitude is 2500 meters, you are clear to dive when the swimmers are clear."
When the swimmers are back in the support boat, called the Avon, the Avon Coxswain (pilot) reports, "Alvin, Avon, the swimmers are clear." "Roger Avon, this is Alvin diving..." The pilot vents his ballast tanks and another trip to the bottom begins. Back to top.
Tomorrow
Tomorrow filmmaker Mike deGruy and chief scientist Rich Lutz, along with pilot Steve Faluotico, will make the second to last Alvin dive of this expedition. The end is drawing near - but there is still one more IMAX dive to be made, and the site it will visit is sure to be a grand finale.
Stay tuned! Back to top.
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