That is very interesting! Do you ever see the giant catfish as big as a van that some other FReepers with underwater jobs have mentioned?
Thanks "Interested" for your interest, there's so much here I will try not to go too long. (I guess I did)
Does Remote Observation Vehicle mean that you are actually in the Vehicle when it descends, or is it an unmanned Robot that you control from the launching ship?
The Vessel is 250 ft long and 55 feet wide with 2 moon pools cut though the deck, one for the ROV and the other for work wires, etc. for construction work. The vessel is equipped with a "Dynamic Positioning System" consisting of a DP console on the bridge wired to the thrusters of the ship. The DP operator keys in commands activating thrust of the ship. I monitor and send 4 independent Differential Global Position Systems (DGPS) and Acoustic Transponder Reference positions from the seabed to the DP desk. The vessel then moves by the commands from the DP operator based these signals. He only needs to type in a range and bearing and the vessel drives itself to that point and stops. We can then "hold station" within a few feet indefinitely for months in the same spot and in any depth of water without the aid of anchors. The whole operation is monitored with Real Time Graphics displays showing the outline of all moving objects to scale as well as any bottom features, pipelines, wells, etc. We use our own navigation software to display these moving and stationary objects in whatever projection we are working in. What used to be done by hand, computers do every second. Spheroid to spheroid conversions and spheroid to projections (Geodesy)
The ROV is an unmanned vehicle (the size of a van)deployed through the moon pool from a winch drum with 16,000 feet of armoured electrical umbilical. The ROV itself is a very sophisticated ROBOT made of stainless steel tubing layered with specially designed blocks of syntactic foam (very dense foam) to give it slight positive buoyancy. It's loaded with fibre optics for cameras and twisted pairs of wires to run altitude, depth and pressure sensors. Hydraulically driven thrusters that pivot vertical and horizontal are on all sides to stabilize the ROV during operations, it flies like a helicopter but underwater. The ROV is equipped with 2 very strong hydraulically driven manipulator arms to do the work. This whole package rides in its own "cage" designed to carry the ROV to the working depth, the cage also has thrusters and cameras; Once the seabed is reached by the cage, with an altitude anywhere from 50 to 100 feet off bottom, the ROV flies out of the cage on its "tether". Tethers can range from 600 to over a 1000 feet depending on the system. The cage reel on here holds about 800 feet.
The WASP is a "manned" dive suit utilized when more dexterity is needed. The diver enters the suit feet first (there's no legs to this suit, just a compartment for his body in the tail). The suit is mounted on a stand and looks like it belongs in outer space. The Wasp suit's clear Plexiglas "globe" is then shut and sealed. It resembles a "wasp" hence the name. The Wasp is "flown" by the diver using manipulating levers to activate thrusters and arms built onto the suit. The Wasp is totally self-contained with oxygen tanks and only needs a cable to lift the suit over the side into the water via custom deployment crane; the cable remains attached during operations for safety reasons. The depth rating for this pressurized Wasp is about 2200 feet. Being the diver is breathing an air mixture there is no need for decompression as found with systems using a helium gas mixture. Basically its a submarine shaped like a wasp designed for a single person, not for me thank you.
When the WASP jobs are mobilized the paperwork states we need to be in "DP CLASS 2". This means I need not only DGPS but also 2 other independent sources of positioning for input into the DP Desk. It would be catastrophic to have a "drive off" because of a loss to satellite positioning. A mans life is at stake here, so I need 2 Intelligent Transponders positioned on the seabed as "Acoustic References". I actually calibrate these based on DGPS position. The other device is a "Fan Beam", a laser device that remains locked onto a prism reflector pre-installed on a nearby structure. The DP system takes in all these systems and "weighs" them into the solution checking one another constantly 24 hours a day. I wouldn't be typing to you on FreeRepublic during these operations.
Everything deployed over the side or through the moon pool must be tracked. USBL (Ultra Short Base Line) acoustics is the choice for average work but degrades in accuracy the deeper you get to the tune of 1 half % the water depth. So in 4000 feet I could be off by 20 feet at the seabed. This is okay for most of what we do. More expensive but highly accurate LBL (Long Base Line) acoustics is more desirable for construction work. Accuracies are in the order of 1 to 2 feet in any depth depending on the calibration of seabed array.
I mentioned I would try to keep it short, however that’s impossible to paint a picture of things with just a few paragraphs, let me try to finish up
So you can go about a third of a mile under water. What lives that far down?
More like 3 miles down, but very rarely do we go that deep, yet. Average depth is anywhere from 3000 to 8000 feet in the Gulf of Mexico. This is where our technology has taken us thus far in constructing permanent installations in ultra deep water. At these depths the creatures, as rare as they are, move very slow. Some so strange words cannot explain. I would see at times, very large crabs, things growing up out of the seabed like cactus, that seem to sense with contortions the lights of our arrival. At first you ask, is this a plant or some fleshy organism? One time I couldn't believe it, there was this fish, instead of bottom fins it had small legs and was actually walking on the seabed! Some of this stuff is right out of fossil records but they're alive! One other fish, translucent white, strolling ever so slowly one would think of it as a slow motion video, amazing. In shallower depths around 600 feet we get curious visitors. A whale hanging itself in the water column upside down as to get a better view of the ROV, looking right into the lens of the camera. Those are just some of neatest moments.
So, you're looking for damage under water? What sort of damage is that? Are you talking about damage to man made structures, or is this for ecological investigations? Can a hurricane cause damage 1600 feet under the sea? If so, how severe?
Man made structures yes... The industry is still playing catch up from Hurricane Ivan in 2004, Katrina and Rita added insult to injury in a big way.
There are structures in deep water that were meant to withstand Cat5 impact and for the most part they held up well considering they were hit with some say 70 foot waves.
Let me explain the designs first so you may have a better idea...There are 3 major platform designs implemented since 1994 which revolutionized the industry, these were first in the world built in our Gulf of Mexico. One is the TLP (Tension Leg Platform) next is a Compliant Tower (Rigid Steel Tower from the sea floor up, a skyscraper under the water. And finally the SPAR or DDCV (Deep Draft Caisson Vessel)
TLP first design was "Shell Auger" called TLWP which is TLP "wire assisted". Then came "Shell Mars" TLP, no wires. Steel tendons manufactured in Japan (they look plastic their so perfectly milled). These tendons are assembled together with special oil filled connection joints $40,000 a piece (no welding). The 250 foot sections assembled run the length to the seabed and stab into foundation piles pre-installed with an underwater hammer (German). LBL Positioning required, with inclinometer Compatts for verticality. My division manager wrote a story for Oil and Gas Journal and the first line of the first paragraph was: Imagine dangling a pencil by a string from the top of the Empire State building, landing the pencil in the middle of a nickel on the sidewalk below. That’s the accuracies in acoustic surveying needed to install the Shell Mars TLP foundation piles. The topside of the tendon stand is then attached to the bottom of 4 giant pontoons with 4 tendons stands per pontoon, the pontoon is actually the hull of the rig. The rig is ballasted down until the submerged top of the tendon comes in contact with the hull locking them in. The rig is then de-ballasted (floating the rig upwards) pulling tension on the tendons, hence its name TLP, all of this done in 4000 feet of water.
The DDCV is a floating structure much like a huge pipe section, though this one is 800 feet long and 150 feet in diameter. The hulls are built in Finland and shipped across the Atlantic on special transport ship. These Caissons are then brought to the site and flooded by pumping in seawater until it is vertical. A temporary work deck is then lifted to the top as a stage to run the chain winches for mooring wire recovery. The chains are attached to mooring piles 3 nautical miles out from center of location rising up to meet the hull which is now vertical. Usually the depth of water is around 4500 feet upwards to 6000 feet water depth. After all of this, a massive deck section is then installed on the top this caisson. The S7000 SSCV (Semi Submersible Crane Vessel) performed the lift for Exxon’s Diana DDCV, total weight of the deck was 9000 metric tons, and that was only one of 2 deck sections. The dual cranes on the S7000 have a combined lift capacity of 14,000 metric tons. Diana has 12 anchor piles / moorings holding her in position. Exxon engineers estimated 4 moorings would be more than sufficient to withstand the forces of a Cat5 hurricane, A bit overdone but we’re talking billions of dollars for just one platform. Each mooring cable is coated for protection and should last more than 30 years. We're talking some big stuff here, the interconnect and chain is massive with one link of chain weighing over a 100 lbs, just 2 links is the height of a man. The counter pin for the shackle looks like an artillery shell.
The Texaco Petronius Tower (Compliant Tower) is a "free standing" structure the height of the Sears Tower in Chicago except its underwater!
These facilities described above are still there after Ivan, Katrina and Rita. The main damage was due to very large wave heights smashing some components and modules on the upper decks. But the facilities themselves, in spite taking a beating they survived this awesome force
Where I am at present the water is very shallow in a place known as "the shelf", these are old fields. Water depth is around 75 to 150 feet and these are old structures from the 60s and 70s still producing, some anyway. Ground zero of Katrina cut a path along what is called "The Mississippi Canyon" where the Mississippi River empties into the Gulf. Thousands of years of sediment gave way on the seabed resulting in "liquefaction" causing an undersea avalanche. This mud flow I am told was travelling some 300 miles per hour after giving way under the sea. It literally sliced through the steel legs on some of these old platforms cutting them down like butter. All of this mess is on the seabed now, shattered pipelines and tap valves some buried too deep in mud to excavate and repair, they are just simply written off. We are presently using what is a deepwater designed system as a 2 million dollar dunker, just to hold some sonar equipment. But they have the money. The ROV stays in the Cage the whole time, rigged with special sonar devices for mapping called Multi-Beam. The resulting data creates a very impressive deliverable in a 3D mosaic map of the lost rigs. After all is done, someone will be able to navigate the hazards with caution though this maze of debris in order to decommission the still live oil and gas wells. That’s what’s going on. No attention is given to this story and more than likely will never run on television as to not upset Wall Street or drive up already high gas prices.
Do you use acoustic tracking because you can't track visually at those depths? I assume in colder waters that it's very dark at 1600 feet. Is that the case in the Gulf of Mexico?
The water I am in now is very murky but passed 1000 ft water depth is stunningly clear. Even when visibility is good we still need to "map" the area of concern with accuracy. To do this I must first find out the properties of the "water column" from surface to seabed. I deploy a sound velocity probe that gathers: Pressure, Temperature, Conductivity, Density, and Salinity. Based on the values derived we calculate a "Speed of Sound" through the water column for a particular location on that day. There are differences in temperature at certain depths so the "thermal cline" can change. We must check periodically due to weather and currents, seasonal change etc the validity of this data. The values for "Turn around time" in milliseconds are then applied in the Acoustic Processor. I can now acoustically track based on a correct turn around cycle of transmit and receive times. For this shallow water stuff it really does not make a difference in USBL positioning, the cage is only 60 below the hull, I just use the offset for the moon pool and I’m okay. The sonar’s need this turn around time more, so in this instance I just leave the probe logging in real time during data collection. Every time the sonar picks up an object it receives the reflection back to itself thereby creating an image. So its important to have that speed of sound coming in all the time to know how far away the object is for mapping.
Do you ever take the ROV into fresh water? If you're at 1600 feet depth in the Gulf of Mexico, how far out from the shore does that put you?
There are fresh water ROVs out there but they're small and usually hand tethered. Fish eyes we call them and mostly they are used for dam inspections etc. I haven't had any dealings with these ronco pocket ROVs. :)). There may be start up companies out there to make a buck with Home Land Security issues in ports, etc. which may prove to be profitable
Depending on what port you depart from and what part of the shelf East to West you are going, and what the shelf's widest point is, you may have to transit further South to reach 1600 feet of water. On average its about 1 hour helicopter ride or 8 to 12 hours boat transit. One of our main ports of call was a place called Venice, Louisiana. Katrina wiped this place off the map as it was on the tip of the toe of Louisiana’s boot. All the news kept talking about was New Orleans, with little mention of the even lower lining parishes like St Bernard and Plaquemine’s Parishes.
I know I went a bit long here, believe me there’s plenty more I left out. Very rarely do I explain what I do even back home and most certainly not to any level of detail. I may have gotten too much on the technical side, however I thought it nice to bring it life that way.
You may think differently about where I am this coming hurricane season. I will not be out here should another Katrina come I grant you that. Once is enough...1985 Hurricane Juan... still to this day the imagery of that experience lingers. 50 foot waves 400 feet apart with 120 mph blistering winds...The sea looked as though it merged with the sky...large amounts of water being vacuumed up in a torrent of chaos. Like giant fingers formed of black clouds scooping the tops of the swells like hands feeding a monster. Yes, I will be home on dry land for certain.
Now back to discussion about the "One" in control of all these things
Thanks again, God Bless