ROV survey of a dam

[Bill Bulloch]

Lost Boy, Thanks for highlighting those points.
Access can be a major hassle and be the difference between a succesful or unsuccesful survey.
Point taken on the divers compass. Have you used a LBV for anything like this? With its overlay and dual cameras, especially the FO models with the smaller diameter umbilical, look, on paper anyway, a very suitable system for dam inspection. Anybody got any valid opinions?
Cheers

[Andy Shiers]

Sorry Rovdo , I have not used one so cannot comment.
Is the survey to be carried out straight down and on the outside or internal following tunnels ?
Small is good but you really need a ROV with some Ompf if it is to go any distance.

[c]

rovdo pm sent

[James McLauchlan]

I’d also be interested to see some LBV experience being discussed openly in this thread so that it may add to the overall picture.

Lostboy brought out a good point. When you need to lower a vehicle a good distance before hitting water you are already using up valuable umbilical length on that alone.

For example: The AC-ROV may have a working depth of -75m but it also has a maximum manufacturer imposed tether length of 120m, full stop.
With anything over 45m of air before hitting water to be able to work in water at -75m it would need to be deployed from a boat.

[Craig Thorngren]

I’d also be interested to see some LBV experience being discussed openly in this thread so that it may add to the overall picture.

James,
Do you think it would be a good idea to start a topic concerning the differences in the ROV’s in this thread or starting a whole new one?

Ideally, I think an entire new section might be best. Keeping it under "dam inspection" just doesn’t seem to do it justice. There is another website that lists alot of ROV’s with the manufacturers specs and even has a link to reviews. The problem is that the link to reviews doesn’t work so it’s really just a site for manufacturer’s to promote their product. Something similar so that users could post their comments (good or bad) and discuss the merits of using different units in different situations could be beneficial to all.

Thoughts?

Chief

[James McLauchlan]

Chief

I was close to suggesting that earlier in the thread when the AC-ROV, LBV, Falcon debate started to happen, but as the dam inspection topic seemed to be still under discussion I thought we could let it run for a bit.

I’m inclined to agree with your suggestion that it may be better to start a new thread on the subject of Micro/Mini ROV’s and see where it leads.
Work class and light work class ROV’s are all well and good but these days Micro/Mini ROV’s have established themselves are more than ‘unreliable toys’ so worth debating.

I’ll start a new thread and see what happens….

Update:
OK…. the new thread is: HERE

best regards
James Mc

[Rons_ROV_Links]

http://www.deepocean.com/civil.html

Deep Ocean provided technical, service, and initial operational support to Vortex Marine Construction. A standard Phantom HD2+2 was utilized to perform a variety of critical path construction support tasks in a first-of-its-kind repair of the Walter F. George Dam on the Chattahoochee River, located at the border of Alabama and Georgia.

The ROV with sensor suite provided rapid metrology and QA monitoring feedback and reporting of a tight tolerance set of underwater construction tasks under harsh and potentially hazardous conditions. DOE provided the initial deployment of equipment, operating personnel, and technical expertise in a rapid project start-up. Thereafter, DOE helped train the ongoing operational personnel, while continuing the technical support and parts, repairs, and troubleshooting back-up throughout the project.

This approach provided remarkable quality and speed of completion for the project with an excellent safety record. Unpredictable working conditions in a complex civil works project tested the ruggedness and reliability of the ROV system, the result was: zero (0) project downtime. Vortex recently received the Safety Award from the US Army Corps of Engineers, who gained the appreciation of the importance in utilizing ROV systems in lieu of divers for difficult and dangerous underwater inspection and construction tasks.

Please see the Hydro Review article about the Walter F. George Dam project in Alabama

Recommend ROVs by DeepOcean:
– Vector L4
– Phantom® HD2+2
– Phantom® P150E
– Triggerfish

Also check out this DeepOcean page: http://www.deepocean.com/rovMind.html

[digitellus]

Nobody has mentioned the Sub-Atlantic Navajo yet? I have operated both Falcon and Navajo and would pick Navajo everytime for video inspection. The navajo will outperform the falcon in stronger current too. But the Falcon has a nice open frame which allows you to fit sensors and hydraulic packs etc. Falcon controller is slightly better also versus the standard PS2 controller that comes withthe Navajo, this is good and bad depending on your preference, some love the PS2 controls while others (older!) hate it.

The Navajo’s we have run have all been ultra reliable if maintained and we have never changed out a thruster yet. The Falcon has been a pain through cheap low cost parts being used to build the thrusters which can take no abuse at all, 1 plastic bag in the thruster and you will be changing it for around $10,000 sing dollars. Sub_Atlantic spares have been slow to get our hands on but starting to improve , Seaeye are good most of the time but will charge you for everything they can, we wanted to access the programme for the video overlay which requires a password, Seayeye want your credit card number before they give any passwords out! WTF, we bought the thing now we have to pay the fix it!

Small vehicles of this size are a bit of a hit and miss I feel, most of the time you are in more need of a very good pilot who knows how to get himself out of the poop!

[Martin Wareham]

The Navajo is very powerful for it’s size.

http://www.sub-atlantic.co.uk/Navajo.html

Not exactly a micro ROV, but definitely a mini. As far as an open frame verion is concerned ……… 😉 (Sub-Atlantic employee :D)

[Craig Thorngren]

most of the time you are in more need of a very good pilot who knows how to get himself out of the poop!

More importantly is a pilot that know’s how to stay out of it 😀

Chief

[digitellus]

most of the time you are in more need of a very good pilot who knows how to get himself out of the poop!

More importantly is a pilot that know’s how to stay out of it 😀

Chief

Yes but any decent experienced inspection pilot should be able to get into dodgy areas and get himself out to gain the best results, comes with the territory. oh and has been the death of many a small sub, how many RCV225’s or Sprints are still alive today, i think most would have been blended in thrusters or lost in jackets..haha horrible bloody things

[James McLauchlan]

The Navajo is very powerful for it’s size.

http://www.sub-atlantic.co.uk/Navajo.html

Not exactly a micro ROV, but definitely a mini. As far as an open frame verion is concerned ……… 😉 (Sub-Atlantic employee :D)

I feel the unit may be a little heavy … as mentioned earlier hauling a unit up and down a dam wall by hand might be on the cards…

In air it weighs: 42 kg (93 lb)

[digitellus]

Yes you would struggle to haul the Navajo up a dam wall, even from the side of the vessel its a 2 man job and you cant pull up on the tether. In the case of a dam then the micro machine is the practical way to go unless you can get access from a boat

[Craig Thorngren]

I just finished inspecting a regulating dam yesterday. The dam was almost 60 years old. The water had been running so hard and long over the years that it actually scrubbed away a lot of the cement exposing the rebar. It was quite a snag hazard. I will say the sonar was absolutely critical in showing some of the damage as well as for navigation.

There were several area’s that I didn’t want to fly the VideoRay into because of the hazards, but the sonar was able to image the debris and condition of those area’s perfectly (you could see the exposed rebar quite clearly on the sonar). Vis was around 2-4 meters.

Chief[/img]

[James McLauchlan]

Thanks for that. Good to get some feedback on actual dam inspection experience using one of the vehicles mentioned in this thread.

[Author]

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