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BLUE ROV as mini-me


(Todd Sparkes) #1

I have a possible 4 week job for my ROV. It would be integrated into a work-class system and sent out to inspect hard to reach spaces that the work-class cannot access. There are a few unknowns. Will I need anything special to transmit and recover the signal off a fibre network? The depth is 120 meters. I can purchase the new aluminum enclosures but will the end caps and dome stand the pressure at depth?


(Jacob) #2

Is there an ethernet switch or router on the work class? If so, I imagine that’s all you would need, but I don’t have any experience working with fiber networks. Can you provide any more details about the network configuration and communications interfaces/hardware involved?


(Todd Sparkes) #3

Signal over copper to a multi-channel multi-plexer system usually with RS232 and RS485 channels. Video is usually a separate channel but the same as anything you get out what you put in just de-mux at the surface and run copper to the laptop. Running the Blue2 signal directly up a short tether then into the multiplexer should be the same as a straight copper run. I am more concerned about the end caps and dome holding up to the 120 meters depth.


(Jonathan) #4

The end caps and the domes will stand up to that pressure just fine. We have been testing the aluminum enclosures with our standard aluminum endcaps and flanges installed and they were still functional when the tube failed. We have also tested two domes so far and they have failed at a depth of well over the 100 m that they are rated for.


(Todd Sparkes) #5

Thank Jonathon. Good to know.


(Todd Sparkes) #6

Have you pressure tested the standard enclosure to a maximum depth? An updated spec sheet for the system depths would be great.


(Jacob) #7

With the advanced electronics package, all of the communication is done over Ethernet, so the multiplexer will need to be able to support that.

The standard electronics package uses RS-422 serial communication and analog video, which sounds like what you might need if the multiplexer does not support Ethernet.


(Jonathan) #8

We haven’t had a chance to test the 3 and 4 inch acrylic to failure yet. The 3 inch tube will definitely be fine at 120 meters. The 4 inch tube is more of a question mark, but we should have a chance to test in the next week or two.


(undersearobotics.com) #9

I suspect the epoxy-potted penetrators might be the weak link when going deeper than 100m. I’ve found some very slow leaks that the only thing I can attribute it to is a leaky penetrator. How deep have you tested them to?


(Jonathan) #10

We have tested the penetrators to 900 meters several times without incident.

We have seen a slow leak on one of our test BlueROV2s that we suspected was a penetrator, but we found that one of the cables had a cut in it and water was leaking in through the wires. I am pretty sure that the cut happened during assembly. I replaced two Lumens with four and zip tied the cable right on top of a cut zip tie which was pretty sharp. It passed vacuum but started to slowly leak at around 40 meters.


(Todd Sparkes) #11

At what depth did the dome fail?


(Rusty) #12

Hi Todd,

We’ll publish the dome failure depths once we’ve completed testing. So far we’ve seen catastrophic failure at depths below 700 meters, but we’ve seen some less catastrophic damage at lower pressures. I don’t want to give the exact numbers yet so as not to be misleading.

-Rusty


(Todd Sparkes) #13

Thanks Rusty. A whole new spec sheet with updated depth ratings would be good. The reason I am asking for the dome depth rating is a potential customer is very impressed with the new ratings of the enclosures, the dome now seems to be the weak point. He is interested in the increased depth rating but concerned about the dome.

Regards
Todd


(Rusty) #14

Todd,

Okay. I can tell you that the theoretical calculations (performed in Under Pressure), show a dome failure depth of 340m, but those are usually very conservative.

-Rusty