We have a BlueROV2 that we already dived and worked well. But now, after some months abandoned, we tried to dive it again, and it started to leak.
At first we thought it was the main junction, through the big O’rings. But after close inspecction, we figured it was through the potting of the penetrator. It seems it is a common issue for what I saw through the forum.
The problem is: here from where we are (Spain), the epoxy resin you recommend for the potting (loctite marine epoxy) is not distributed, so we want to know if there is an alternative we can use.
Also, what is the correct procedure to repair this? do we need to cut the wire and insert it in a new penetrator? or can we put this resin on top of the old one and solve the issue?
Cobalt connectors is a good alternativ to replace bad potting penetrators.
thank you for your fast answer,. The problem with that is that we need a solution asap. Also since the robot is already built, changing all the penetrators would cause big trouble.
We are using Scotchcast 2131 with good result. You can see if you find that.
and where do you usually buy it, it is comercially available online?
Rough up surface of cable about 3/4 inch above the potting material, as well as the surface of the potting material on penetrator (use a dremmel tool). Then make a dam with tape around the pentrator around 1/2 higher than the potting material already on the penetrator and pour the Scotchcast. Had to do all of my penetrators as you could see the cables separating from the potting material…Hmmmm
Good luck but mine is working and seems to be holding. Also replace “o” rings on battery compartment often due to opening and closing the compartment.
You can simply “unpot” your faulty penetrator, just look at this subject
Then, after careful cleaning and degreasing with isopropylic alcool, you can use a PU resin like UR5528 from Electrolube ( easy to find in Europe )
Anyway, the cobalt connectors are a good alternative, and are in stock in my webshop !
Surprising how easily the epoxy come out with a heatgun! didn’t know that. Re-potting the penetrators after that might be easy.
About the kind of epoxy we are going to use, we got from a spanish distribuitor Loctite EA E-90FL, which has been previously recommended here in the forum for potting. About the cobalt connectors, those look like a good replacement for the actual penetrators. Maybe in a future we start buying and installing them.
…just a question, did you wash Everything in fresh water after every dive?
Havent dived the robot in salt water yet, so…
ok? Strange, maby its been used too much hardener in the epoxy mixture, so it cracks?..i havent had this problem so might be that? …guess BR can answer this? …but to change to scotchcast (3M, might be a better solution?)
We already solved the problem with SOL-RES 01 flexible polyurethane from Scorpion Oceanics. The cured two-part resin is water resistan and electrically insulated.
We did not even “unpotted” the old resin, we just put the new on top of the old one, covering all the holes that appeared. It has been working perfectly since then. Here is a gif of the air escaping from the penetrator resin after I applied positive pressure in the chamber underwater (before reparing the fissures):
BR is now working on new penetrators that dont need any kind of resin, because this is not the first time this issue has happened.