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First dive, first observations


(Nikos Maurommatis) #1

Hi everybody,

last night I had the first semi-professional dive with my BR2. I have been twice in a pool and at least 5 times testing dives in real sea before the last night dive. I write some observations so as to help each other:

a) We had 4 dives in depth of 45-48m. In all dives after 35-45 minutes I had “Communication Lost” in QGroundControl and I was forced to pull the BR2 to the surface. When the BR2 reached the surface everyhing was fine with no problem…In the main housing I haven’t used Silica Gel, is that so important? Can you suggest anything else? Had anybody else the same issue? Any recommendation?

b) After the last dive and without knocking the BR2 anywhere we had a broken motor nose!
IMG_20180419_002514|280x500. Had anybody else the same issue?

Thank you for your comments,
nikos


(Jacob) #2

Hi @nmau,

Have you been able to connect to the ROV again at all? Do you see video?

We cannot see the picture, can you please try again?


(Nikos Maurommatis) #3

Hi @jwalser,

When BR2 reached the surface we reconnected without do anything, very strange…anything at all . No battery reconnect, no QGC restart, no BR2 restart…nothing.

How can I post an image so as you can see it properly? May you help me?

Nikos


(Jacob) #4

This behavior sounds like there might be some sort of continuity issue, please verify all of the connections are well-seated, especially on the tether communication interface boards.

You should be able to drag the picture into the window. I think just something weird happened the first time you did it.


(Nikos Maurommatis) #5

@jwalser, the issue about continuity was the first thing I thought. But how can you explain that the communication was established three times when the BR2 reached the surface? It was really weird. Of course I am going to do a number of test dives again when I will manage to change the broken motor nose…


(Jacob) #6

My guess is the problem would be a transient connection. It touches, then it doesn’t, then it does…

Do you mean that there is some sort of repeatable behavior to make it stop working, then work again?

Wow on the thruster. Did you tighten the screws very tight?


(Todd Sparkes) #7

Nikos,
I was on a dive spread once during which we had a self enclosed camera that worked perfect on the surface.
Every time we went in the water to an approximate depth the camera would stop working. We did a lot of troubleshooting without any luck. Eventually we did find the problem inside the camera. It was a small solder edge on a wire which when the camera would compress at a certain depth the solder edge would short against the camera housing. I agree with Jacob and Rusty you have an issue with a connection - possibly shorting to ground when you hit a certain depth. Good luck.


(Nikos Maurommatis) #8

@canman172, thank you for your comment, I have to think where to start cheking…

@jwalser, yes it was repeated three times. That is the weird…

No the screws weren’t overtighten. All motors were mounted the same time by the same way. May I print the broken hose? Is available any 3d model or do I have to order some spare parts?

Nikos


#9

Could it be a problem in the tether, which is only present when you let out the 40-50 meters of cable?


(Adam) #10

Hi Nikos,

Wow, that’s some pretty major nozzle damage! Please email us at support@bluerobotics.com. ad we’ll see what we can do.

-Adam


(Nikos Maurommatis) #11

@Mikxie, I don’t know. The dive was about 45-48 meters depth but the used tether was much longer. The tether was free all time. I have 200m tether. I wll try to make more tests next days.

@adam, I will send you a mail. Thank you.


(Matt) #12

Another factor to consider is temperature.

Was it always happening at a certain depth or after a certain time at that depth?
Eg … if you went straight down quickly to 45m would it drop out? or was it after being at that depth for a certain amount of time that it would drop?
Did you note any of your internal temperature readings?

Its possible you might have a component which has become temperature intolerant or moisture is forming and shorting something. If your going semi-pro you might want to consider flushing your enclosures with nitrogen before a dive, a second vent plug is handy here. This is fairly common practice for most 1bar enclosures in the ROV industry. This will help stabilize your enclosure atmosphere and reduce if not eliminate moisture and fogging. But having some descants paks in there is never going to hurt.

Just something to consider buddy.
Hope you work it out.


(Nikos Maurommatis) #13

@BayDynamics, the connection lost was happing after a certain time of dive. The depth of dive was always the same (45-48m). My first thought was the moisture/temperature of housing and this is the reason I first asked if the Silica Gel is so crucial.

May you give me some more details about “hidrogen flushing” method, I am very interested in it because I would like to plan some very deep dives in the future (Greece is full of war wrecks).

Thank you in advace!


(Matt) #14

If you have some silica gel paks definitely put some in. You will always want as much moisture out of your enclosure as you can get. Putting a few Silica Gel paks in will usually do the trick so your best bet is first to try using those, definitely the cheapest approach.

NITROGEN is an inert gas which actually absorbs moisture. If your worried about moisture or your domes fogging up and you dont want to risk it then you can flush the enclosure with Nitrogen before the dive.

  • Get a gas bottle and connect it in to your vent plug with your Vacuum pump plug and release the gas in. Ideally you will need to put in a second vent plug to let the gas escape but if not you can loosen the flange a small amount to let the gas out.
  • The idea here is to try and replace the air inside so its only Nitrogen inside instead. Flushing the gas through for about 30 seconds is typically enough.
  • Make sure when your finished that you have not applied excess pressure to the enclosure, let it momentarily open to air to make sure your at 1bar pressure.
  • There are different grades of nitrogen and the choice is really what your willing to spend. The better the grade the less oxygen and moisture content there is. But for your purposes what ever Nitrogen you can get will be fine.

I would try a dive with Silica Gel to start and see how that goes, the humidity of your location will play a role in how much moisture gets in to your enclosure so dont be afraid to put a few in, you cant hurt anything by using them.

Hope it works out mate.