lewko

OK. You know more about ROVs than I do, but I was under the impression that Ocean Shield shipped out with a TPL, an AUV and a little ROV (maybe not a Remus 6000, but still...) They also have the Echo standing by with a lot of other electronics.
This is a three-week 'old' link now:
http://www.news.com.au/national/weat...-1226864685171

[Quote] The US Navy will deliver a Towed Pinger Locator for the Ocean Shield in the search for the black box.
They will also provide a CURV-21 Autonomous Underwater Vehicle.[unquote]

Here are the specs n the CURV-21 from http://www.supsalv.org/00c2_curv21Ro...2&pageId=2.5.3 :

(Check out the Lift Capacity)

CURV 21

Curv CURV-21 is a 6,400-pound Remotely Operated Vehicle (ROV) that is designed to meet the US Navy's deep ocean salvage requirements down to a maximum depth of 20,000 feet of seawater. This vehicle is loaded with a host of new technologies and was built as a direct replacement for CURV-III but with a smaller overall system footprint.

ORION and CURV-21 can be combined into a single integrated search & recovery system capable of being deployed on a USNS T-ATF. The system is based on a .680 fiber-optic umbilical cable and a shared handling system that can switch at sea between side-scan sonar and ROV operations. The system is self-contained and fly-away transportable for world wide response on vessels of opportunity.

The ROV can be controlled in all six degrees of motion with auto-control functions for depth, altitude, and heading. An integrated DVL allows 1 and 2 meter incremental movements as well as cruise control for extended axial movements. The vehicle is equipped with CTFM sonar for target location and pinger detection. The ROV uses two seven function rate manipulators. It has a high-resolution digital still camera, black and white, and color television cameras. The system includes a load bearing, pressure compensated, Electro-Optical Umbilical Swivel.

The fiber optic multi-plex system can combine up to eight channels of video, sonar, USBL, RS-232/422/485 data communications, and navigation data on a single fiber. 2 spare fibers are available subsea for additional sensors. A digital communications network with a data capacity of 400 MHz controls the vehicle and has significant capacity for future expansion. The system is designed to interface easily with additional sensors or tool packages using standard data formats.

For special operations, the ROV can accommodate customized tool packages. These packages can include, but are not limited to specialized salvage tools, instrument packages, or other mission-oriented equipment.

GENERAL SPECIFICATIONS
VEHICLE
Length - 8 ft
Width - 5 ft 0 in
Height - 7 ft 0 in
Weight - 6,400 lbs

PERFORMANCE
Depth - 20,000 ft of seawater
Speed - 2.5 knots
Power - 45 Hp
Auto Controls - Depth, altitude, heading, cruise, auto translate
Lift Capacity - 4,000 lbs via ROV frame & umbilical (releasable)
Payload - 240 lbs.

Manipulators & Tool Packages
Two 7-function Schilling ORION Manipulators rated at 150lbs @ 5ft.
Custom tool packages: Guillotine cutter, rotary grinders & tools, and T-handle shackles w/ heavy rigging.

INSTRUMENTATION

Navigation
1 x Electronic Gyrocompass
1 x Attitude and Heading Reference Unit
1200 kHz Doppler Velocity Log
1200khz Doppler Velocity Log
Altimeter, 200Khz
Ultra Short Baseline Tracking ( 17Khz)
Emergency Locators - Acoustic beacon -37.5 kHz
Strobe flasher - high intensity Xenon (100-hr life)
Radio Direction Finder

Sonar
CTFM with 2000 ft. maximum range with pinger locator
(27/37/45 khz)

Cameras
1 x 460 Kongsberg 1364 color video on pan and tilt
1 x 400 Black and white Fixed pilot camera
1 x 3.3 Meg Pixel Digital Still with strobe

Lights
4 x 250 Watt Halogen fixed
2 x 400 watt HMI

[Update]
I don't know if this is true, but i saw a post by 'underfire' on prune that said that Ocean Shield is packing a Remus 6000:
http://www.pprune.org/rumours-news/5...-lost-504.html

There is also a lot of mixing of terminology so an AUV can be a ROV. I don't really know what the boundary of the definition is. I couldn't find a verification of which ROV is on OS. Anyone know for sure?

Hill713

So at this point, the chances they find the FDR is.... 1 in 100? 1 in 1000?

bimmerdriver

Thanks for your post. Now that you mention it, I recall reading that the CURV is deployed on the Ocean Shield. The CURV is a USN asset, designed to be deployed on "vessels of opportunity". Ocean Shield, like many offshore vessels is a "vessel of opportunity" for ROVs, specifically "work class" ROVs or WROVs, such as the CURV, as well as for AUVs.

An WROV system is very large, consisting of a huge winch (typically 4000 m or 6000 m in the case of the CURV) for the umbilical and tether management system (TMS) and the control room, which for such cases is typically built inside a large shipping container. The TMS is typically either a top-hat which sits above the WROV or a cage, which houses the WROV. When the WROV is deployed, it's lowered to the operating depth while still attached or inside the TMS, then it detaches and "flys" away from the TMS, to the maximum length of the tether, which is typically up to 1000 m in length.

AUV systems are relatively smaller and simpler. They consist of a launch and recovery system (LARS) and a control room, also typically built inside a shipping container.

It's usually pretty easy to tell an ROV from an AUV. ROVs are rectangular shaped and they always are tethered (i.e., connected) through the tether / TMS / umbilical to the surface vessel, from which they are powered and "flown" by a human operator. AUVs on the other hand are practically the opposite. They are torpedo like, fully self-propelled and autonomous. They are programmed with a mission, then they are launched. After that, they carry out the mission, then surface to be recovered. There are "grey areas", but that's pretty typical.

AUVs are good for covering a lot of territory, but they can't stop and take a look or pick something up. ROVs are relatively slow and because they are tethered, they are usually operated from a stationary vessel or relatively slow moving vessel. They are great for moving around in 6 degrees of freedom and making turns about 3 axes. Many of them can lift and carry heavy loads. They also have cameras, lights, sonar and manipulators so they can look at things, take pictures/videos and grasp things. In search and recovery operations, AUVs do the searching and ROVs do the recovering.

FYI, a REMUS is an AUV, not an ROV. If the Ocean Shield has a REMUS 6000, I find it surprising they would be diving the Bluefin beyond its maximum operating depth, but there could be valid reasons for doing so.

I hope that helps.

polarbreeze

The point is that they were going on about suspecting the ELTs had been disabled, more conspiracy theory stuff. That's the nonsense. I don't normally watch CNN but I have watched them a few times for this event and they are clearly more interested in delivering sensationalized entertainment rather than real news.

lewko

Yes it does, thanks. i can see there might be better AUVs and ROVs but Ocean Shield is already in position and capable of going to the depth that is currently required and and bringing back some smaller pieces of debris if it finds them.

http://www.jacc.gov.au/media/release...ril/mr029.aspx

[quote]Early this morning, Bluefin-21 AUV completed mission seven in the underwater search area. Bluefin-21 has searched approximately 50 per cent of the focused underwater search area to date.

The focused underwater search area is defined as a circle of 10km radius around the second Towed Pinger Locator detection which occurred on 8 April

No contacts of interest have been found to date.

Bluefin-21 AUV's eighth mission has commenced.[unquote]

Whatever Abbott says, Bluefin will probably search for another week until they get 100 % of the 300 sq km target circle covered. I looked at a map of the AF747 debris field and the vast bulk of it was in a 500 m X 250 m oval. MH370's debris field may be a little bigger because it is deeper.

I don't want to exclude the possibility that they will bring in another AUV but it seems they would want a consistent mapping of the entire area using one method before they try another method to overlay the first.

In terms of luck, they wasted the first week searching the South China Sea. The search was reasonable based on what was known, but wrong. Then a lot of well-intentioned, but wasted effort went into chasing the satellite photos of ocean debris. When Inmarsat produced the arcs of actual radio contacts it narrowed the search area considerably and the refinement of the earlier radar contacts narrowed the search field even more. That is when the Ocean Shield deployed the TPL.

Ocean Shield was very lucky to have heard the pings from the FDR the first day out in the newly refined area. The pings faded fast over the next few days and are gone now, so they deployed the Bluefin.

I think the odds of the Bluefin finding some debris go up every day until they cover 100% of the search circle. The blackjack analogy is that the deck is getting richer so it's time to increase the bet. If the Bluefin finds something they can drop the CURV and try to pick it up.

If the Bluefin finds nothing they will have to try something else because they will have obviously missed it. Switching to craps: "Seven, the line loses. New shooter coming out."

bimmerdriver

I didn't hear the report and if that's what they did, I'm not surprised. However, confirming that the aircraft actually had not just one, but four, ELTs is newsworthy and like I said, debunks some lines of speculation.

buckeyefanflyer

How do you loose a 777. I feel sorry for all the passengers and their families. 7 weeks and no trace and CNN is running out of ways to cover this.

bimmerdriver

I agree, it's very lucky indeed that the Ocean Shield was in the right place at the right time to detect the beacons. If the wreckage is ever found, it will be due firstly to Inmarsat and secondly to the TPL.

Now that they know which "corner" of the ocean the aircraft went down in, they just have to keep looking until they find wreckage. It's not a matter of whether the Bluefin is the best AUV or not, or whether the mapping is "consistent", it's a matter of how much area one AUV can search. The more AUVs they have, the more area can be covered.

Once the wreckage has been located and mapped, they will probably deploy more OSVs (and ROVs) to the location, although if the wreckage is deeper than 4000 m, there are not a lot of ROVs capable of doing the job, because most WROVs are rated to 4000 m. That's unfortunate, because while the CURV can dive to 6000 m, it's not the most powerful or capable vehicle compared to many others. A 777 is a very large aircraft and they may have to recover a lot of it to determine what happened. It will be a monumental task.

lewko

I'm no expert, and if the search is visual or covers a very large territory then it seems to me a lot of them would definitely help. I think the search right now is doing a mapping with sonar and maybe the kind of sonar they are using is very strong and would interfere with others using the same kind of mapping technology in the same area.

What I find weird is they are still sending a fleet of planes every day to do an aerial search for debris in an area 1000 km SW of the Ocean Shield. The weather there is bad and even if they drop a marker buoy the chance of a chase ship finding the debris is very small, and then all they have is possibly a seat cushion or the odd piece of luggage, assuming they can see something that small from the air.

aussienanna

Much has been said re the function of the Ocean Shield in the search zone but I cannot recall what equipment the HMS Echo has onboard and her role in the search. Would someone please be so kind as to refer me to the appropriate entry or else enlighten me.
HMS Echo has been skirting just outside the main search zone and doing much zigzagging back and forth so must have some capacity.

Thanks.

ExpatExp

Am not familiar with aviation ELTs. Are they the type which require a person to remove them from their storage bracket in order to switch them on?

luckypierre

No, they are activated by unusual G forces on the device. Their absence in this tragedy certainly adds to the mystery.

bimmerdriver

AFAIK, the Bluefin can carry either an edgetech side scan sonar that operates at 120-410 kHz or a reson multibeam that operates at 400 kHz. They are probably using the side scan because it covers a wider area. The range of this sonar is not so great that there isn't plenty of space for more than one vehicle to operate. It probably comes down to availability.

Regarding the ships, they are presumably searching for surface debris to unambiguously confirm the aircraft went down in the region. Since they haven't found any wreckage (yet), they still don't know with 100% certainty that they are in the crash location.

luckypierre

I presume the Bluefin generates a finely detailed map of the bottom. From a search perspective, what are the benefits of such detail at this point rather than use a more powerful transmitter aboard a ship, such as the survey vessel Echo. At 4K meters, can a surface ship image a structure like a 777 debris field on the bottom? If so, seems to me that the sweep area would be significantly larger with a surface vessel and allow a much more rapid search. Is there any difference in the return signal after pinging off an aluminum and steel surface? Once committed to a particular search alternative (ie Bluefin), is it possible to "tune" other sonars to avoid increased noise in the search area?

bimmerdriver

Good questions. The problem is the depth, specifically the range. The 4500 m depth creates two problems that make an AUV much more effective for "mapping" than a vessel on the surface. Two key parameters of any sonar are the resolution and the range. This is oversimplified, but a typical hydrographic sonar will have around 0.5 to 1.0 degree resolution. By the time a 1 degree beam reaches the bottom (from a surface vessel), it will have spread out to almost 80 m, meaning it will only detect very large strong targets and even then, there will be very little detail. Not good if you're trying to locate a debris field with unknown target size. Also, for a sonar to have 4500 m range, it must be very high power and very low frequency. The lower the frequency, the lower the resolution. That's why it's impractical to survey the area from the surface and conversely why an AUV works so well. Unfortunately, an AUV can cover only a relatively small area, but at least if there are reasonable sized targets, it's more likely that they will be more visible than they would be from the surface. Of course, all of that depends on the conditions of the bottom. If the bottom is very soft and the debris sinks into it, the debris will be difficult to detect. If the bottom is very rocky, it will be difficult to distinguish debris from rocks. There isn't much difference between the return from different types of metals. They tend to be good acoustic reflectors, which makes aircraft wreckage relatively easy to detect.