T500 Depth Rating

The T500 thrusters are rated at 300m but the T200’s don’t have a depth rating.
What is the factor that limits the T500?
Is there a depth rating for the T200?

Hello guys,

for the T500, the depth rating is said to be 300m. Any chance it can work in 500m? Isn’t it the same potted design as the T200?


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Hi @etienne,

I’m not certain what the reasoning was here, so I’ve asked about it and will get back to you :slight_smile:

Following up, initial validation samples had some issues with delamination around the cable at large depths. We’re working on a process to mitigate that, but that hasn’t yet been fully validated, or implemented on the manufacturing line.

We wouldn’t recommend using T500s that have been produced with the existing process beyond 300m depth without using a water-blocked connector (to ensure no water ingress to the enclosure via the cable), and testing prior to deployment.

Hi Eliot,

I do a bracket that houses the ESC which is oil filled. One side is a cobalt connector the other is wetlink going to the thruster. In this condition the Thruster cable is balanced. As long as the Potting on the thruster coil and contacts are good. Shouldn’t be an issue.
What do you think?


To me that at least seems reasonable in theory. That said, I don’t have experience with oil-filled enclosures, so don’t know how resistant oil is to allowing in bubbles of water in a rigid enclosure, and whether that’s dependent on the temperature, pressure, and type of oil involved.

I see the ESC’s have Electrolytic capacitors. Are these essential?

The Basic ESC 500s use COTS (commercial off-the-shelf) PCBs, so we can’t really say, because we don’t have the detailed reasoning behind the design that would enable us to suggest whether a non-hollow capacitor alternative could be suitable.


Hi @gcelec,

I’ve moved some older comments here from the original T500 launch thread, since they’re relevant to this discussion.

I don’t believe there have been any updates to the production process since that initial discussion.

Short answer (from the Technical Reference), they’ve been tested to work to at least 500 msw.

Slightly longer answer (from the T200 product page):

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Hi Eliot,

We have an ROV system made of Bluerobotics components.
The T500s are the components with the lowest depth rating.

We have cobalt connectors and I’m trying to understand if they’re considered water-blocked connectors. But either way we also don’t want to get water inside the cables.

I understand you have a depth rating for a reason, and we understand that it’s our risk to bear. But I’d like to understand the risk of operating at 350m depth.

Can you share any info on the depths the delamination around the cable began to occur?

FYI our T500s are new, so if there’s an updated model that mitigates this risk it would be great to know if there’s a new model number or month of manufacture where these issues are no longer a problem.


Any update on this topic? does someone knows if using connectors for example, from https://www.bluetrailengineering.com will increase the depth rating?

thanks in advance

Hi, just saw on What is a Thruster? - Blue Robotics that outland technology has a 600 meters depth rating rov that uses T500, the rov in question is the ROV-3000.

this might imply that the T500 thruster should be capable of reaching 600m without problems.

Fascinating stuff.

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